MacInTouch Reader Reports

Hard Drives: Partitions and Formats

Mar. 7, 2009
Mar. 9, 2009
Mar. 10, 2009
Mar. 11, 2009
Mar. 12, 2009
May. 28, 2009
May. 29, 2009
May. 30, 2009
Jun. 1, 2009
Jun. 2, 2009
Jun. 4, 2009
Jul. 16, 2009
Jul. 17, 2009
Jul. 18, 2009
Jul. 20, 2009
Jul. 21, 2009
Aug. 18, 2009
Aug. 19, 2009
Oct. 21, 2010
Oct. 22, 2010
Oct. 23, 2010
Oct. 28, 2010
Nov. 1, 2010
Aug. 18, 2011
Aug. 19, 2011
Aug. 20, 2011

Newer entries...
Mar. 7, 2009


David Charlap

Apologies if this has already been asked and answered before.

My Mac (a QuickSilver-2002 dual 1GHz G4) has two hard drives in it. The first one (the Apple-provided 80GB drive) has the OS on it. The second drive (one I installed) has two partitions: a 10GB partition with a second installation of Mac OS X (for disaster recovery purposes) and the rest for data storage (mostly my iTunes library.)

I've found that ever since 10.5 shipped, my 10GB emergency-boot partition isn't big enough to let me install large system updates. I need to do things like delete unused languages and un-universalize applications in order to make enough free space to update that partition.

I'd like to non-destructively repartition the drive to move another 10GB from the data partition to the emergency boot partition.

What programs, if any, do MacInTouch readers recommend?

My own searches only located one application with this capability: Drive Genius. Ordinarily, I'd give that a try, but I also found some rather scary reports about Drive Genius corrupting drives, so I don't want to consider it unless people here (who I trust more than random reports found by Google) consistently report problem-free operation of its repartition feature.

[I'd advise against resizing partitions to guard against major data loss (and I would *never* resize without a good, complete backup), but, for what it's worth, here are a couple of related links.... -Ric Ford]

Mar. 9, 2009


Christian Liljestrand

Disk Utility can make a perfect sector-copy of your disaster recovery partition to a new, larger partition (or an image file) on another drive. (Yes, it sounds like it's time for a third drive, preferably larger than the combined sizes of the other two.)

The only drawback is that once you've got the new drive, it'll be very tempting to take advantage of its very-likely-much-better performance by migrating everything to it. (Been there, done that, many times over the years.)


Ned Christopherson

iPartition works great for me.


Philip M

I've used Leopard Disk Utility to repartition on the fly. Leopard Disk Utility, unlike in all previous versions of OS X, can non-destructively resize, as long as you are not using a Master Boot Record. (You are probably using APM or GUID.)

I've actually been stupid enough to do this without backups, twice, and never had a problem. And that's on an external USB drive that had three partitions on it.

Just make sure you are in the right dialogue in Disk Utility: if it says it will erase everything, it -will-.

In Disk Utility, select the master disk; i.e. the one that has the unchangeable name that shows up in the System Profiler, like "74.5 GB SAMSUNG HS082HB." (on my 1st Gen Macbook Air, e.g.). This will be at the top level in Disk Utility. Your partition or partitions, i.e. "Macintosh HD" (default) or whatever you call it (them), will be below that one, indented.

After you click at the highest level, it will shade, and a new option will show up along the horizontally placed buttons in Disk Utility: "Resize". -That- is the option you want. Click it. From there you just drag the slider(s) on the partition map on the left to change the size of the appropriate partition(s) and hit apply.

You can even add new partitions by hitting the + button. N.B. It takes Leopard a while do to this. Be patient, and for God's sake remember to have everything plugged in and running off its own power source.

I boot in Safe Mode and make sure I don't have anything else running when I do this. It's always a little scary...

Oh, and I've never tried this with a Boot Camp partition present, so I don't know what effect all this has on that sort of stuff.


Ronald Shudnow

You should use Diskstudio by Micromat. It will allow for repartitioning your drives to whatever size you desire without losing existing data. Their website is I have used this application many times without problems.


Stephen Hart

David Charlap asked about repartitioning.

First, for disaster recovery, for example restoring from Time Machine, you can just keep an image of the Leopard DVD on the 10 GB partition. You don't need an up-to-date version of the OS for that.

Second, the perfect way to have an up-to-date version of the OS available on a separate disk is by cloning your hard drive to an external drive using Carbon Copy Cloner or equivalent. You get a complete data backup *and* a startup drive all in one.

Third, if you really want to repartition a drive, the obvious safe way to do it is to clone all the current partitions, check each, erase and repartition the internal drive and finally clone back what you want. Bonus: you have a backup.


Philip M

Sorry, my memory seems to have played tricks on me. What actually happens when you click on the icon for the physical main drive is that "Partition" shows up in the buttons, not "Resize". You click on "Partition" and then follow Disk Utility's instructions to resize.

"To erase and partition the selected disk, choose a volume scheme, set options for each volume, and click Apply. To resize the volumes on the selected disk, drag the dividers between them, and click Apply."

If Disk Utility says "this will erase", you've done something wrong (not resized). Go back!


Wijnandt T. de Vries

Try Disk Studio of, the maker of TechTool


Josh Penn

I would very highly recommend Coriolis Systems iPartition:

as well as iDefrag, not that you are looking for that. iPartition has been able to handle *anything* I've thrown at it, including HFS+ case-sensitive, as well as NTFS Boot Camp volumes with a WinXP Pro x64 guest OS on it, even though Coriolis states that is not supported. They state they support Windows XP and Vista 32-bit guest OSes. But my 2006 Mac Pro won't run Vista 64-bit, even though it has an ATI Radeon HD 3870 mac/pc card (I thought that the ATI X1900XT was what prevented Vista 64-bit install disc from working -- not so!) So to get Windows to recognize my 10 GB of RAM (as well as for the extra registers and protected kernel), I went with XP x64. I'm extraordinarily happy with it, and it handles Crysis, Call of Duty 4 and CoD World at War like a dream.

The only drawback to iPartition is the somewhat funky "pie-on-a-dial" interface, for lack of a better description. But once you get used to that, it rocks.


David B.

David Charlap asks about non-destructively resizing partitions on one of his hard drives.

Short answer: Try Apple's own Disk Utility (if you've got back-ups).

Before Leopard was released, there was talk that it would include "live" resizing of disk partitions. I'd forgotten all about this until the issue came up for a friend last November. I searched Apple's Knowledge Base to no avail, but did find two pages in Disk Utility's own Help file, one called "Enlarging a volume" and the other called "Creating new volumes on a disk."

Since then, I have had success adding, deleting and resizing partitions/volumes on several drives (all happened to use the Apple Partition Map). When you enter a change to the size of an existing volume, Disk Utility will either accept or reject the change before you have to apply it. There will also be a note next to the selected volume that says whether or not it will be erased when you apply the change.

In your case, if your emergency volume is at the beginning of the disk, you may need to delete it, enlarge the data volume to fill the entire disk, and then create a new emergency volume at the end of the disk (this will make more sense once you've read those help files).

If you've got full back-ups, though, might it not be easier just to wipe the disk, partition it, and restore the data from back-up?

Or, since you're willing to spend money on software, I'd urge you instead to replace your seven-year-old 80GB start-up drive with a new, larger and faster drive ($73 for 500GB at Newegg), rethink your whole partition and storage scheme, and never look back.


Ken Spencer

For David: I was facing that same space problem, and then realized that for the price of Drive Genius, I could buy a new, larger drive for the same price. I cloned the OS to an external drive, installed the new drive, formatted it with a MUCH larger OS partition, and cloned the OS back. I am thrilled with all the extra space on both the OS partition, and the additional storage I ended up with as well. I think you will be happy with a larger drive.


David Charlap

To all those who have made suggestions, thank you, and a few comments:

1: Disk Utility doesn't work for me. I tried to perform the first step (shrink a partition to make room to add to the other partition) and got the error "Filesystem resize support required, such as HFS+ with Journaling enabled." The volume is HFS+ with journaling enabled. I can only assume that there are other requirements as well. Perhaps it needs an Intel processor?

2: If I wanted to throw out two perfectly functional hard drives and restore everything from backups, I could do that without asking anybody any questions.

3: The emergency partition is for more than just restoring from backups. I also boot it when I want to do things like run Disk Warrior on my normal boot partition. Yes, I can boot the DW CD, but that's a lot slower and I can't use the Finder to test-mount the rebuilt directories if I do that.

4: I have complete Time Machine and Retrospect backups of all the partitions in question. If there is no other choice (or if something goes wrong during the resize) I can restore from them, but I knew that before I posted my question. As with the "throw out your hard drives and by new ones" answer, I consider this a last resort option, not a first or preferred option.

5: Josh: Thanks for the recommendation about iPartition. Ric also mentioned it (but without a recommendation.) It sounds like what I'm looking for. Have you tried it on a G4, or only more modern systems?

Mar. 10, 2009


Becky Waring

Most of the time, we post here about things that go wrong, but I today I have a story about some great customer service I received from Alsoft, makers of DiskWarrior.

A couple weeks ago, I wrote to ask if anyone could help with my external hard drive, which would not mount, and had irreplaceable videos on it. The drive would periodically simply refuse to mount via FireWire, yet would then be able to be reformatted and used again, with Disk Utility and other hard drive tools reporting no problems. And yes, it was always ejected correctly. I wondered if there were a way to recover without reformatting and losing the data.

A few posters suggested I try DiskWarrior on the drive, but I also got an email directly from Marc Moorash of Alsoft, who noted that I was a customer of theirs, and offered the following:

"From your description, it sounds as if the problem is that the partition map has been overwritten. If there were only one partition on this hard drive, I could probably work with you via iChat to repair/rewrite the partition table. We actually do this quite often with our DiskWarrior 4 customers. However, with two partitions on the drive then the repair becomes very tricky to perform remotely."

Marc then offered to try to recover the drive if I sent him it to him and paid for return shipping. Of course I took him up on his amazingly generous offer, and sent the bad drive, along with a new one to put any recovered data on.

Voila, I just received the new drive back on Saturday, and all is restored! Marc even promised to dispose of the old drive securely, since I don't want to ever see it again... I am immensely grateful, and still somewhat stunned at his generosity -- he asked for no payment other than that I be a DiskWarrior customer.

In case other people have similar problems, here is what Marc said about it:

"The main problem with the drive was that the location of the GUID Partition Table (GPT) had been overwritten by other data.

"Amongst other reasons, this can happen due to:
1) An extraordinary amount of pre-existing directory damage and data being written to the wrong location.
2) A drive unmounting improperly (and the drive cache writing data out to the drive) in an attempt to save the data.
3) A physically failing hard drive (at which point all sorts of oddities can occur).

"Using the directory data that was remaining on the hard drive, I was able to work backwards and recreate a valid partition map and utilize DiskWarrior to recover the files."

Marc also said that while partition maps don't go bad very often (they are a relatively rare occurrence as dead hard drives go), rewriting them is a complex undertaking, and live partitioning, which David Charlap asked about recently, is a bad idea:

"To recreate a partition map, one needs a fairly intricate understanding of the way an HFS+ volume is put together as well as understanding how partition maps are formatted. So, while all that information is available from Apple, it isn't a straight-forward process - and becomes more complicated when a drive has multiple partitions.

"Not an impossible task, but one that if done incorrectly can cause additional problems. This is also why "live partitioning" a hard drive is generally a bad idea - it is a tricky process to move everything around just so, and have all of the data still accessible.

"All in all, glad I could help out. I enjoy rebuilding partition maps (as weird as that sounds). It presents a number of challenges that tend to be unique to each hard drive. It's like a jigsaw puzzle, without a box top to know exactly what the final image should look like."

Obviously Marc & Alsoft can't provide this service free of charge for everyone, even their customers, so don't all pile on at once. Perhaps they could charge separately for the service if they get a lot of takers. But I just wanted to report back about what the problem turned out to be, and the great experience I had working with Marc. Alsoft certainly has me as a dedicated customer now...


Peter Kluytenaar

For David: I have used iPartition on both G4's and Intels and it has worked flawlessly for me.

Mar. 11, 2009


Motti Shneor

Regarding Becky Waring's wonderful experience with Marc Moorash of Alsoft, I have a question to Mr. Moorash of Alsoft.

Some 20 years ago, I used to do this job of reviving corrupt diskettes, and hard-drives, and I remember the joy of solving-the-puzzle too.

However, It always happened that after doing a task many times, you start to realize a pattern, that in most cases can be translated to a computer program that will imitate the solving-process.

Such programs are Alsoft DiskWarrior, and many other beautiful tools that once were considered "Impossible" to do, or home for the "Irreplaceable Human".

Now isn't it time that you - Marc - write a program to resolve such rare problems? I see a business opportunity for Alsoft here!

You do not have to do it deterministically. You can "half-guess" a configuration, then try it, and let the user tell you if you succeeded, just as you do in DiskWarrior --- try, and only when user approves the fix --- replace the partition table.

Or is partition table a totally different thing than "normal" file-system problem?

Mar. 12, 2009


Josh Penn

David: Previous to the 2006 Mac Pro, I did own a PowerPC G4 (AGP graphics), and I did have, if I recall, a couple rare occasions to use the 1.x.x version to resize HFS+ partitions (but not case-sensitive). I never had any issues with it whatsoever. At some point it seems to have made a jump to version 3.x.x (I don't recall a v. 2), but I do know iPartition 3 is a much more mature product than any previous version.

Actually, looking for what the difference is with the demo, I found their FAQ, which states: "iPartition 1 will not rearrange files within a partition; you have to use the included iDefrag Lite utility to compact the files within your partition before attempting to resize with iPartition (using the "Compact" algorithm)", while "iPartition 3 does have the ability to automatically compact files as required although in some, rare, circumstances you may still need to run iDefrag Lite." But as I said, I never had any problems with any version I have used.

They do state that it supports Mac OS X 10.3.7 or later (including Leopard), on a 400MHz PowerPC or better, or any Intel Mac. The demo version, BTW, lets you do everything but commit changes. Full disclosure: I have no affiliation whatsoever with Coriolis, but I do like their products (all 2 that I know of :) and I think they do a terrific job with bug fixes and enhancements in their products.

May. 28, 2009


Nikki Hill

I have a problem in that my Quicksilver G4 is only showing up one part of my hard drive when I start up - the other has apparently disappeared. I have no programming knowledge, I'm afraid - can anyone advise/help please? I am running Tiger.

Thanks in hope!


Sterett Prevost

Re: Nikki Hill and G4 tower

By, " part of my hard drive..." I assume you mean that the internal hard drive was once partitioned into two partitions(Mac volumes) and now one of them does not mount on the "desktop" after boot up. If so, the directory on that volume may be corrupted, and you'll have to boot from the Tiger Install DVD and run its Disk Utility program. When DU is open, you'll click on the icon of your hard drive in the left column, then click the <First Aid> tab, and finally click the <Repair Disk> button on the lower right. If any repairs are reported to have been made, run <Repair Disk> again, until no repairs are reported. Then try a normal startup.

May. 29, 2009


David B.

For Nikki Hill's disappearing partition (if that's what it is...), here's another possibility:

If yours is the original Quicksilver model from late 2001 (Machine I.D. PowerMac3,5 - check in System Profiler), it can recognise internal hard drives no larger than 128GB in size.

If your hard drive is larger than that, and the second partition is on a part of the disk past the 128GB point, you [were] likely using a handy bit of software called the "SpeedTools ATA Hi-Capacity Driver" from Intech Software (link:, and that something has happened to interfere with its operation. The first thing to try would be to re-install this driver.

Is it possible that someone set this up for you in the past and that it has "just worked" ever since, so you've forgotten about it? If not, ignore this entire post.

May. 30, 2009


Bradley Dichter

Perhaps the larger-than-128GB drive has the Intech Hi-Cap driver, but the machine was upgraded to a newer version of the operating system unsupported by the installed version of the driver and all that may be needed is a updated hi-cap driver. Also if the directories are damaged on the second partition, and Disk Utilities is not able to fix it, you may need stronger commercial software like Micromat's TechTool Pro or the lighter version TechTool Deluxe that came with AppleCare Protection Plan. Not that it makes much difference, but perhaps there were two hard drives and not one partitioned one and the second one has the problem. Easy to check that by opening the side door and looking for one or two drives.


Karl Ploessl

Every single update (10.5.6, 10.5.7) deleted/inactivated my SpeedTools ATA Hi-Capacity Driver. After reinstalling the driver the partitioned drives showed up again (this is on a G4 Cube running 10.5 with a 320 GB hard disk)


David Luckhardt

In my experience (professionally supporting various Macs in corporate and military environments), the issue of what formatting can boot what Intel mac is more complex than just APM or GUID.

I found that this changed with the Santa Rosa chipset MacBook Pro models, released in the summer of 2006. Although Apple had announced earlier that Intel Macs required GUID partitions on boot drives, it didn't 'take effect' until these systems shipped.

I had four different external hard drives from two different makers, all partitioned via APM into three volumes. Previous to the Santa Rosa MBP release, I could use all the partitions to boot and install updates on/from for both PPC and Intel Macs, for both desktops and laptops.

Once the Santa Rosa MPP's were shipped, I had to reformat half the drives with GUID so that I could boot from the new MBP's and install onto the partitions -- otherwise they were marked as unusable in the Apple installer with the red exclamation mark.

So if like most Mac support techs, you need to boot from a partitioned drive and run Apple system installers, you'll need to format the drive/partitions with GUID for newer Intel Macs.

Jun. 1, 2009


MacInTouch Reader

David Luckhardt states that the Santa Rosa MacBooks were the first Macs that only booted from GUID partitioned disks. He's wrong - all current Intel Macs boot from either APM or GUID. They have to, since the system disc itself is APM (that's how both PPC and Intel can boot a single DVD).

What can't be done (and has been true for all Intel Macs) is installing OS X to an APM-partitioned disk. The only way to make a Universal boot drive is by installing Leopard to an APM drive when booted from a PowerPC Mac or via cloning. Also, firmware updates for Intel Macs require booting from a GUID partitioned drive.


Phil Benware


"So if like most Mac support techs, you need to boot from a partitioned drive and run Apple system installers, you'll need to format the drive/partitions with GUID for newer Intel Macs."

David, respectfully, I would have to disagree with this suggestion...
Just this past Thursday, I was teaching a disk imaging and restore session using 4 brand new MacBook Pro (Early 2009) models. I booted ALL of them from APM formatted USB and Firewire drives without issue. I've also booted a Mac Pro (Early 2009), as well as various other Macbooks, MacBook Pro's and MacBook Air's using APM formatted drives. That's all I use for the moment, since we still have many PPC Macs on campus. The only thing I needed to be sure of was that the external drives had Mac OS X 10.5.7.

The OS used to boot these machines was originally built on a Mac Mini (Core Solo), which is one of my test machines. After building and updating the OS, and configuring some other useful applications, I did a little clean up then imaged that os. That image was then applied to my APM formatted Firewire and USB drives. (I've also applied this image to USB Flash drives, but they are exclusively formatted as GPT volumes).


David Ryeburn

David Luckhardt comments that a GUID partition is now needed for MacBook Pros released since the summer of 2006. I have no experience with MacBook Pros, but my summer 2007 2.16 GHz MacBook will boot nicely from an external Firewire drive with APM formatting. What I could not do was to *install* the Intel version of Mac OS 10.4 on that drive. However by repartitioning the drive GUID style and installing onto it in that state, making a file backup of that drive with Retrospect, repartitioning the drive APM style, and restoring from the backup, the MacBook now boots from the drive. Since doing this, I have installed all subsequent system software updates up through 10.4.11 as well as other relevant Apple software updates (e.g. Security, iTunes), without going through the GUID, backup, APM, and restoration process again, and all has gone well.

I suspect that if I want to move to 10.5 I will have to use GUID formatting for the initial installation and then go through the backup, APM, and restoration sequence as I did with the initial installation for 10.4.

Why would I want to do this? The drive in question has three (APM) partitions -- one a small PPC startup partition, one a small Intel startup partition, and one (the largest by far) for general storage purposes. Each startup partition has a wide assortment of repair utilities on it.

I got the idea for this repartitioning, backup, and restoration trick from a web page at Other World Computing.


MacInTouch Reader

Regarding universal boot volumes, Apple has a knowledgebase article titled "Mac OS X 10.5: Creating and maintaining a bootable 'universal' external disk" at


David Luckhardt

This happened the last time I tried posting here about the APM / GUID formatting / booting issue -- folks seemed to misread the post, and focus on the boot function only. There is more to the issue and my post.

I clearly say in my original post from 5/30 that the issue is linked to booting AND installing OS and OS updates:

"Previous to the Santa Rosa MBP release, I could use all the partitions to boot and install updates on/from for both PPC and Intel Macs, for both desktops and laptops.

Once the Santa Rosa MPP's were shipped, I had to reformat half the drives with GUID so that I could boot from the new MBP's and install onto the partitions -- otherwise they were marked as unusable in the Apple installer with the red exclamation mark."

So yes, you can boot Santa Rosa (and later) chipset Intel Macs from APM formatted partitions. But you can't run system installers or updaters on those partitions -- an essential element of the discussion (and my job).

Here is my last sentence from the 5/30 post, where for the third time I mention booting AND running system installers:

"So if like most Mac support techs, you need to boot from a partitioned drive and run Apple system installers, you'll need to format the drive/partitions with GUID for newer Intel Macs."

Jun. 2, 2009


Jeffrey Harris

[Re. lost partition]

Buy DiskWarrior.

If it cannot solve your problem, I'd be very surprised and your hard drive may be toast.

It's saved my and many a clients' hard drives from troubles.

The best $100 you can spend to keep your Mac healthy. I've used it for years. I have a 4-digit (under 2000) serial number.

Jun. 4, 2009


MacInTouch Reader

David Luckhardt wrote:

"Here is my last sentence from the 5/30 post, where for the third time I mention booting AND running system installers:

'So if like most Mac support techs, you need to boot from a partitioned drive and run Apple system installers, you'll need to format the drive/partitions with GUID for newer Intel Macs.'"

I'm going to have to disagree. We use drives that are APM formatted and with several bootable partitions (10.4 and 10.5) and a full set of install partitions (10.3, 10.4, 10.5, optional server install partitions).

They are capable of booting and installing PPC and Intel cpus. There are some limitations however - the only system installers that boot and install on Intel are 10.5.x; there are no "generic" 10.4.x install discs for Intel. Instead we have a "generic" 10.4.11 image that can be restored. Can't do an archive and install, but migration is an option.

Obviously 10.3 is PPC only! The 10.4 bootable partition we use is PPC only - if we want to run tech apps we boot intels from the 10.5 partition. No luck using an Intel 10.4.11 source to boot PPC & Intel. I've seen claims it can work but didn't easily for us and not really necessary. Could have separate PPC & Intel 10.4 bootable partitions but not worth the drive space for us.

To summarize, on our APM-formatted disk:

10.5 - bootable utilities & system installer - PPC & Intel
10.4 - bootable utilities & system installer - PPC only
10.3 - system install - PPC only

10.4.11 "generic" Intel image kept as .dmg for restore when needed but CAN boot Intel when restored to APM disk.

Basically, an Intel booted from an OS install disk will refuse to install to an APM formatted drive, but there are ways around that...

The whole setup has proven VERY useful and can really speed up OS installs!

Jul. 16, 2009


Larry Nolan

I originally partitioned my external Firewire drive with three partitions.

Disk Utility shows this information:
first partition: 50.31 Gb (used for a no-longer-needed disk clone of a friend's iMac)

second partition: 150Gb (used for most recent clone of my iMac),

third partition: 264.88Gb (my iMac's Time Machine backups)

I'd like to eliminate the first partition and use the freed space to make the second and third partitions larger but not invalidate either the clone or Time Machine backups.

Is this possible with Disk Utility (OS X 10.5.6) or is there some other software that can handle the task?

Jul. 17, 2009


Bob Murphy

Larry Nolan asks about deleting a Firewire disk partition in Mac OS 10.5.6, and resizing a couple of other partitions to use the freed space.

Apple says you can use Disk Utility for that ( - delete the partition first, then resize the others.

However, I shuffle partitions a lot, and tend to be very cautious about that kind of thing. Rather than try to resize "live" partitions with important data, I back everything up using Carbon Copy Cloner, re-partition the drive, and restore everything with CCC.

If he doesn't have free space elsewhere, external USB or Firewire drives are reasonably inexpensive on Amazon or NewEgg, and then he'll have another backup volume.


Scott Boone

Regarding Larry Nolan's partitioning situation:
It is possible to do what you'd like to do, maybe ;)

Apple provides a command-line command diskutil that can help you out. I would recommend doing a man diskutil in Terminal to get the full instructions for this powerful command. Additionally, you might want to google 'sudo diskutil mergePartitions' a while too. This command allows you to merge multiple, sequential on-disk partitions while keeping the first partition intact as long as it is a resizable type (JHFS+, not FAT32).

Basically the hiccup in your setup is that the first partition is the partition you want to destroy, keeping the second. Unfortunately, the diskutil mergePartitions command keeps the first and destroys the subsequent partitions. You might be able to work around this by cloning the second partition over onto the first (if it will fit), then perform the merging.

As always, make sure you have ALL your data backed up! Playing with partition tables can be a "Bad Thing" for your valuable data if something goes kablooey.

Jul. 18, 2009


Tracy Valleau

With all the usual caveats about danger and backups, the best live re-partitioner I've found is iPartition,

Slightly, um, "interesting" interface, but once you figure it out (drag the outer rim) it seems very safe and efficient.


David Charlap

Larry Nolan asked if it is possible to use Disk Utility to delete a partition and use the space for two other existing volumes without messing up Time Machine.

It is my understanding that the Disk Utility in Leopard can do this if you have an Intel-based Mac. The ability, however, does not exist for PPC-based Macs.

There are also commercial utilities, like iPartition, which should also be able to do this.

But a lot of people here will tell you to not bother trying. Any kind of repartitioning like this is risky, so you should make a full backup before proceeding, and once you have a full backup, you may as well just wipe the drive, repartition, and restore.

As for how this will affect Time Machine, a close friend of mine used Carbon Copy Cloner to copy everything to a new drive (as a part of upgrading a laptop's internal drive.) Time Machine's first backup took a long time, but that time was mostly spent just scanning the drive. The actual amount of data copied was pretty small, so I assume Time Machine did ultimately recognize the restored volume as the original.


MacInTouch Reader

Larry Nolan should evaluate iPartition,
for his hard drive partition rearrangement and maintenance needs.


Emmett Gray

I have used Disk Utility (in Leopard) to resize active partitions and create and remove partitions without erasing the entire drive. It works very well and I have not lost any data doing it. But it has the following limitation: you cannot relocate the starting block of a partition; you can only shrink or expand it.

You cannot, for example, delete the first partition on a disk, then expand the second partition "upwards" (so to speak) to utilize the empty space. But you can delete the second partition and expand the first one "downwards".

To resize, delete, and create partitions in Disk Utility, select the drive (not the partition) in the left-hand panel, and then select "Partion" from the menu. You will see the partition map and can modify it. Nothing will occur until you proceed to the next step, when a confirmation dialog appears telling you what will happen if you proceed. If you cancel, nothing is touched.

The primary reason I have resized partitions is to allow block-level cloning, which cannot occur if the destination is smaller than the source.


Thomas Casselman

I missed the original post; however, I have found an excellent way to repartition without losing data. Drive Genius 2 from Prosoft has a unique way of reformatting partitions. For a given drive, it presents the volumes as slices of a pie. As long as there is counter-clockwise right next to the partition you want to expand, one can expand into the free space. If the partition in question does not meet the above requirement, then one can move it before repartitioning.

I have used Drive Genius about 10 times to repartition, delete, and re-size volumes without losing any data!

The software is pricey but I figure rather spend ~$60 then losing data that could cost thousands to recover if even that is possible.

Jul. 20, 2009


David B.

David Charlap wrote:

"It is my understanding that the Disk Utility in Leopard can do this if you have an Intel-based Mac. The ability, however, does not exist for PPC-based Macs."

Not true. I've used Leopard's Disk Utility to perform live resizing of partitions (without data loss) multiple times on a G4. YMMV.

Also, to the original poster: We had a long discussion on this topic in March of this year in this very thread. Lots of great information can be found by searching MacInTouch.

Jul. 21, 2009


David Charlap

David B. wrote:

"I've used Leopard's Disk Utility to perform live resizing of partitions (without data loss) multiple times on a G4. YMMV."

Odd. I've tried it a few times. It always told me that it is incapable of completing the operation.

Aug. 18, 2009


Boris Starosta

Hi, I've researched the older Macs' 128GB drive limit on your board here, and I thank you all for your comments so far.

I have a Quicksilver 2001 800MHz DP (I think) that has (at least under Tiger OSX v.4.11) had no trouble fully utilizing 250gigs on a Western Digital (blue) Caviar 250GB drive (42, 60, and 130gig partitioned via OSX disk utility).

This drive I had hooked into the "stock" ATA port on the motherboard. Thus, I think my machine must have been one of the later ones that can read the higher capacity drives.

Here's the specs on my machine via system profiler:

Machine Name: Power Mac G4
Machine Model: PowerMac3,5
CPU Type: PowerPC G4 (2.1)
Number Of CPUs: 2
CPU Speed: 800 MHz
L2 Cache (per CPU): 256 KB
L3 Cache (per CPU): 2 MB
Memory: 1 GB
Bus Speed: 133 MHz
Boot ROM Version: 4.2.5f1
Serial Number: XB1360RTKSJ
Sales Order Number: M8361LL/A

My problem is that the WD 250gig drive has failed. WD kindly and promptly sent me a replacement which is a 320gig drive. Now the 320gig drive is not showing the full size to the Mac - it is showing only 128gigs to Disk Utility, which is the limit for the older Macs. So the replacement is useless to me....

The question is, why did my Mac have no trouble with 250gigs, but is balking at the 320gigs? So far I've found no answers online.

I'm in touch with WD about this as well, and promise to report any resolution of the issue here.

Many thanks.

Aug. 19, 2009


Charles Denlinger

You should make the first partition 128gb or smaller, and use Intech, Hi-Cap Driver 10.5 $25.00. They have an older version for Tiger. Make that first partition your boot drive, other volumes can be any size.


Gregory Weston

Boris Starosta asked why his 2001 QuickSilver could see the full capacity of a 250GB drive but only 128GB of a replacement that's 320GB is reported in Disk Utility.

I found this somewhat strange comment at LowEndMac:

There is conflicting information about "big drive" support. Apple doesn't list that as one of the Macs that supports large volumes (over 128 GB) on the internal hard drive bus, but several readers have reported successfully using 160 GB and larger hard drives on that bus. At this point, we believe that the 2001 Quicksilver is not afflicted with "big drive" issues. That said, Disk Utility may show "big drives" as having 128 GB capacity even though the Finder is aware of their true capacity.

So *possibly* it's just a quirk of DU. What's the Get Info window for the drive show?

Alternatively, perhaps you were using something like Intech's replacement driver
and had forgotten or didn't know.


Robert Howells

Re the Quicksilver 2001 hard drive problem:

All Macs with a Boot Rom of 4.2.8 or below have the 128 Gb hard drive limit .

Boris's old hard drive likely had the SpeedTools special driver which allowed a full sized drive to be seen.

This special driver requires any operating system to be on the first partition which must be no larger than 128 Gb.

There are separate drivers if you wish to boot OS9 as well as OSX .
The drivers are available here:


Sterett Prevost

Re: Boris Starosta and WD 320 in G4 Quicksilver

Mactracker shows your sales order number associated with a G4 that has large hard drive support not provided. Folks with larger hard drives used to partition them into less than 128GB segments before installing them in the case so the whole drive could be used; perhaps that was true in your case with the WD 250? If you put the new drive in a firewire external case and connect it to the G4's firewire port, all 320 GB will be recognized from the start and the drive can be used as a boot drive.


Lee Clawson

Boris Starosta asks about his G4 Mac seeing 250 but not 320 GB hard drive...

There was variation on the ability of the Mac to see more than the 128 limit. Seems like you now see this previous limit with the 320GB drive.

My advice is to buy a (serial ATA) SATA card. We have a Tempo card ($30) in an older G4 and problems are gone, plus use of the newer higher capacity drives is greatly expanded.


MacInTouch Reader

You very likely had your drive installed beyond the limit via a software driver, like this here:

As far as I know only three options are viable: 1. Using a proprietary software driver; 2. Buying a PCI based and OSX compatible SATA card; 3. applying an open firmware patch to your machine.

I would advise for the latter, as it gives you full and native unlimited ATA size support:

Take your time to read it, don't fear to use it.



Is it possible that because you partitioned your 250 GB into smaller partitions, they aren't considered a single large drive (but 3 smaller ones)? Is the 130 GB partition actually 130 or does it come out to less because of formatting? The 320GB drive IS more than the 128GB limit. You could try creating more smaller partitions just to test it out but I wouldn't recommend keeping it that way. You could also put the 320GB in an external FW housing. I believe there's no 128 this way.

I had a G4 AGP and put in a Sonnet SATA card for this reason.

Oct. 21, 2010


Bryson Jones

This may be more of a question, but I specialize in storage and asset management systems and am finding that we are quickly outgrowing the OS X filesystem in our industry. (video production)

This was spawned from the ZFS discussion, so perhaps it should go there, but I am seeing problems with larger HFS volumes. Basically, they run fine, but if there's a crash, they tend to "fail less gracefully", meaning that volumes over 10TB or so seem to need help beyond Disk Utility to remount after a system crash. (Disk Warrior usually)

This is happening over several manufacturers or storage and on multiple SAN and non SAN systems but the common element is a large, (over 7TB) HFS volume.

I am advising my clients to stay under 7TB or so, if possible and techs from several storage manufacturers I trust also say the same, while some shops report no problems with volumes into the teens.

We can now buy relatively inexpensively a 16TB RAID that gives us 12TB usable space but I'm not convinced that HFS volumes should be that size. (Yes, I know the theoretical limit is huge.) And clients who would never have been able to have such a large amount of data are now regularly running 4-12 TB volumes without much thought given to their management, backup or maintenance. I feel that this, made even more common now by the popularity of cheap FireWire RAIDs that are now getting huge in size, is going to become a growing problem here on the Mac side of things.

Also, before you respond remember that many large SAN systems aren't based on HFS: I'm talking about volumes formatted withe Disk Utility.

Finally, the question: What are folks in the field seeing with really large volumes, and what's your comfortable upper limit?

Oct. 22, 2010


MacInTouch Reader

Is there a SAN or JBOD box that has ZFS running on a microprocessor in the box and that can be used with a Macintosh to put storage on several hard drives? If this does not yet exist, wouldn't this make a great product for massive storage so that the data could be checksum protected with redundancy to allow automatic error correction?


Steven James May

Bryson Jones writes of his concerns over the physical volume size of todays arrays. Historically, my enterprise UNIX clients worried more about the sheer number of files contained within a volume (directory complexity) than the size of the volume itself. On our network here, we run 6TB & 8 TB level 0 arrays via SoftRAID and Sonnett & Firmtek SATA controllers on G5 and MacPros. The only problems to date are the typical sporatic eSATA connectivity problems resolved with a new cable or cable reseat.

In terms of directory size, one of my server volumes (8TB) is hosting 15 million files, thus far without incident.

It seems to me there are probably quite a few variables that would influence the viability of a directory after a crash, volume size being only one.

Oct. 23, 2010



MacInTouch Reader writes:

Is there a SAN or JBOD box that has ZFS running on a microprocessor in the box ...

Several companies offer something like ZFS in a box, which you can access through an iSCSI SAN, CIFS or NFS:

Oracle Sun servers with Solaris, ZFS and a drive array.

Nexenta ( gives away and sells OpenSolaris with ZFS and management software. Add your own commodity hardware.

GreenBytes ( offers [...] systems with many added features.

Coraid ( was offering Nexenta-based systems, until NetApp threatened to sue. ZFS patent issues are still being sorted out.

Using ZFS over iSCSI, CIFS or NFS means you don't get ZFS robust end-to-end checksumming (your data is at higher risk of corruption), and you must manage two boxes.


Lyman Taylor


Is there a SAN or JBOD box that has ZFS running on a microprocessor in the box and that can be used with a Macintosh to put storage on several hard drives?

Yes. Several (for now) .

Nexenta-based. Look in the reseller section on site for hardware resellers.

Nexenta (and some others) repackage ZFS by leveraging OpenSolaris. Oracle has changed policy about how much code for Solaris gets released and when so there is a new project (sponsored in part by Nexenta) to track the upstream changes Oracle does share with outside world: ZFS is OpenSolaris' default file system, so I think Oracle will continue to release at least a major subset (if not all) of ZFS, going forward, when the "open" snapshots of Solaris drop after the closed ones.

One issue, though, is that you lose some protection. From the box on down, you are checksummed, etc, etc. From the network to memory, though, just on whatever is in the connection protocol - for the most part, just less uniform in protection/correction.

Second issue for Macs is that [they] typically don't do AFP (Apple File Protocol) - CIFS/NFS/iSCSI (also apparently does WebDav which I overlooked in another thread) - essentially, all of the "open" and/or majority-used ones. [It's] just not going to be HFS data (unless [they] use iSCSI, but not sure if HFS won't freak out if the disk gets bigger after formatting.)

It is worth pointing out, though, that ZFS makes several core assumptions. One, that several processor cores will be the "norm" (so CPU overhead is slightly higher). Second, that folks are willing to trade off more space for increased protection (so disk overhead is slightly higher also). So, you get more benefits that don't come for free. Additionally, you shouldn't look for a new $100-200 box (e.g, a Time Capsule-class box) to do this right now. A couple more years from now, it will work much better in that price range.

Oct. 28, 2010


MacInTouch Reader []

A recent posting stated: "GreenBytes ( offers Nexenta-based systems with many added features."

This is incorrect. GreenBytes is in no way affiliated with Nexenta. Following is information about the company:

GreenBytes, Inc. is a provider of high-performance, energy-efficient inline deduplication storage appliances. Featuring the world's fastest, most efficient next-generation Hybrid Storage Architecture (HSA), GreenBytes' GB-X Series storage appliances combine highly innovative software technology and advanced power management design with a world-class server platform to address the storage and energy efficiency crises facing today's IT operations. The GB-X Series features solid state technology for tunable IO performance, as well as the industry's highest levels of scalability and reliability in an easy-to-use, cost-effective package purpose-built to bring the efficiencies of data deduplication beyond data protection and into the primary storage market. GreenBytes was founded in 2007 and is based in Ashaway, Rhode Island. For more information, visit:

Nov. 1, 2010


Lyman Taylor


This is incorrect. GreenBytes is in no way affiliated with Nexenta. Following is information about the company...

Technically true. However, the blurb about the company conveniently leaves out the fact that they are leveraging ZFS.

"... GreenBytes' file system is based on ZFS, and the company claimed Sun improperly used GreenBytes' deduplication technology by implementing it within its own storage stack. ... "
[GreenBytes launches entry-level dedupe appliance]

So "affiliated" as corporate entities is wrong. There is a related article link at the bottom of the referenced one above about Nexenta's de-dupe offering. So they compete with each other. However, "related/attached by shared code" is true. The two companies are doing similar things with ZFS as a starting point. So the respective feature sets heavily overlap.

Aug. 18, 2011


MacInTouch Reader

How does one format a 3-TB drive on an iMac? Disk Utility sees only 801GB and not the entire 3TB.

Aug. 19, 2011


David Charlap

An anonymous MacInTouch Reader wrote: "How does one format a 3-TB drive on an iMac? Disk Utility sees only 801GB and not the entire 3TB.."

You don't say ... how the drive has been partitioned, so I'm going to have to make some assumptions and guess at a possible solution....

The problem with all drives larger than 2TiB (about 2.19TB) is that the number of 512-byte blocks is too large for a 32-bit index to reference. (2^32 = 4Gi. 4Gi * 512B = 2TiB). This means that in order to access all of a drive of that size, the OS, its file systems, and the drive's partition table must use indices larger than 32-bits.

Fortunately, Mac OS X, the Mac OS Extended file system and the GUID partition table all support 64-bit indices.

I suspect the problem you're seeing is an artifact of the fact that most drives (including, I assume, yours) uses the old MBR-style partition table. MBR uses 32-bit indices and therefore can't reach more than the first 2TiB.

Check the partition table type on the drive. If it's not GUID, change it to GUID. This will require repartitioning and erasing all data on the drive, but it should allow you to access the entire drive.

If your partition table is already in the GUID format, then you've got a different problem, and we'll need more information to help out.

[Just a reminder to readers that GUID formatting is the recommended standard for booting Intel Macs, while APM formatting is required for booting PowerPC-based Macs. -Ric Ford]


Graham Needham

You need to be running Mac OS X 10.6 or higher to use anything larger than 2TB…


Dave Delaney

I used Disk Utility on my 2010 Mac Mini to format a WD 3TB drive. That was about 4 months ago. I have it connected via USB 2. WD had a couple of firmware updates since the drive was released.


David Tetzlaff


"How does one format a 3-TB drive on an iMac? Disk Utility sees only 801GB and not the entire 3TB."

I think the SATA controller for the drive has to be compatible with the new size, and some aren't... maxing out at 2TB. If it's an external drive in a generic case, I think it's the bridgeboard. I have a bunch of external cases, all of which work fine with 2TB drives, but only one sees my new 3TB mechanism as 3TB. (The others all say like 89GB) If you have it connected internally inside the iMac, and it doesn't see the 3TB, you might be SOL. If it's a 6GB/sec drive you can try Peter Marshall's suggestions of jumpering it down to 3GB/sec... and do let us know if that makes a difference!


MacInTouch Reader


"How does one format a 3-TB drive on an iMac? Disk Utility sees only 801GB and not the entire 3TB."

I recently bought a "bare" 3TB drive that I thought I would use in an existing OWC Mercury Elite Pro external housing which was a year or two old. When I tried it, Disk Utility only showed there was something like 800 GB of space on the drive.

I contacted OWC tech support and they informed me that only their recent Mercury Elite Pro housings could handle 3TB drives. So I wound up buying a new housing which gave me the full 3TB capacity.

The housings looks similar on the outside, but the "guts" have been redesigned and cleaned up to make the drives much easier to install.

Disk Utility handled the partitioning and formatting of the 3TB drive just fine. I suspect the fact that the full 3TB doesn't show up in Disk Utility is due to the chip set in your housing.

Aug. 20, 2011


Steven Klein

[Re: GUID formatting for booting Intel Macs...]

Actually, Intel Macs boot just fine from an APM partitioned drive.

The reason so many people make that mistake is that Apple's OS installers refuse to install on an APM drive if you're running the installer on an Intel Mac.

I'm a Mac consultant and work on both PPC and Intel Macs all the time. To make my work easier, I have a bootable hard drive in APM format. I installed Leopard on a GUID drive, then cloned it to my APM drive. Now that single drive boots both PPC and Intel Macs.

(I actually have two partitions on that drive, one with Leopard, and one with Snow Leopard. And I plan to add a Lion partition, too.)

Another way to get Leopard onto an APM drive is to install it using a PowerPC Mac. That drive will then boot all PowerPC and Intel Macs that support Leopard.

[I think the issue arises when you want to update firmware on the computer. As I understand it, you can't do that on an Intel Mac with a boot drive formatted for APM. This may be why Apple blocks you from formatting a drive for APM when you're formatting it on an Intel Mac. -Ric Ford]


Gregory Weston

[Re: GUID formatting and booting Intel Macs...]

A very minor nit... but Intel-based Macs will boot from APM devices. The OS installer when running on an Intel-based machine won't install to anything other than GUID, but that's not quite the same.... It was, in the 10.4 and 10.5 era, completely possible to put together a single [hard drive] that would boot either architecture.

[I realize it was possible to boot Intel Macs from APM-formatted disks, with enough configuration effort, but I think firmware updates fail in that configuration, and I wonder if Lion can boot from an APM-formatted disk. (Haven't tried it.) -Ric Ford]


Bob Gale

I have a NewerTech Voyager (2009 or 2010 model) from OWC to read bare drives and occasionally transfer items. My Hitachi 3TB drives are completely seen on my 2008 Mac Pro, using eSata connected to an internal PCIe card while running Leopard 10.5.8 (as well as Snow Leopard). I haven't tried it on FireWire but I don't know why that wouldn't also work. Disk Utility shows it has having 2.7 TB capacity, which is par for the course of a formatted drive.


Scott R.

The discussion about OS X recognizing large drives reminds me of an issue I had a short time back:

I had to return a defective 4TB drive to the manufacturer. I wanted to do a secure erase on it (to get rid of credit card data, banking/investment login info, and so on).

Rather than keeping my iMac i7 running continuously for the time needed, I attached it to my old Power Mac G5 running 10.5.x

It took 19 hours; after erasing the drive (1 pass zeroing), though, I noticed that Disk Utility reported the drive as being 3.6 TB in size (DU on the iMac showed it as the full 4.

Was the disk, as a result, actually fully erased? Does the smaller reported size result in 400 GB literally being missed?


Joe Ubertech

In response to Graham Needham (and to anybody else reading this thread in the future) one does not need 10.6 to use a 2TB drive. Support for large drives is much older than that - and mostly hardware-based anyhow.

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