Drive Partitioning: the Revenge

by David Battino

With all this podcasting I've been doing (iTunes link), my G5 tower's 250GB hard drive is almost full. Perhaps not coincidentally, this ol' Mac has been rather cranky lately. I remember reading that once the free space on your system drive dips below ten percent of its capacity, OS X starts to exact revenge, crashing randomly and forgetting things. That sure sounds familiar.

Be that as it may, I just ordered a 500GB internal drive to start offloading some of the detritus like audio sample libraries and disk images for DVDs I hope to watch someday.

The last time I installed a secondary drive, I was so awed by its relative size (20 times bigger than my stock Mac drive!) that I partitioned it into five slices. After a while, that just became a hassle.

So this time, I'm wondering: What would you recommend? One partition for a basic system backup and the rest for files? One big partition? Seven little partitions named after short men with pointy hats? Leave a comment and let us know what works for you.

250GB gone
GrandPerspective says, "You're outta room!"

UPDATE, 2007-03-03: The drive arrived today and, keeping all of your comments in mind, I set it up with just one big partition. Using Grand Perspective, I found that the biggest space-sucker on the old drive was ripped DVDs, so I transferred all of them to the new drive—regaining 95GB in the process! Kinda embarrassing to realize I'm that far behind in my movie-watching.


Carl Grint
2007-02-27 02:41:55
My normal practice for my main hard drive is 2 partitions, one for OS and applications, then the 2nd for files.
This has the added benefit of splitting up the different types of files and thus reducing fragmenting requirements, and of course should there ever be the need to reinstall, you don't have to worry about the Files partition, just format the OS one and reinstall.

Your need is for the second drive, and as you said you found having so many partitions last time a pain, I think that is correct, really 2 should be enough, anything more and you risk getting a point where the space you allocated runs out.
Unless you are using RAID over drives, having so many partitions is always going to bit you in the end.
Personally I would say go 2, the max 3, you should be fine then.
Have fun :o)

Carl Grint
2007-02-27 02:42:44
PS. you are right about 10%, and your hard drive, an OS needs more then 10% margin of the hard drive, so always best to not let it hit 10% or less or it will make you pay :o)
2007-02-27 03:11:36
Unless you want to use a partition for another system to boot from then why do you need to divide it into more then one, you can always use folders for organizing your data. The problem with partitioning is if you change your mind later it si a bit of a pain to undo...

2007-02-27 03:32:28
I used to partition my hard drives long ago. I stopped partitionning with MacOS X 10.2 I think. Now, I use external (FireWire) drives when I need another (system) partition for testing purpose mostly. I also use external drives for backups.

The problem with partitions is exactly the same as with cupboards and wardrobes. You use space till there is no space left. And when there is no space left, you'll ask yourself: why have I partitionned my drive that way?! And then is's pretty hard to change the drive layout when full.

You should backup your files instead of relying on multiple partitions. I saw hard drive failures much more often than partition corruption. And you should keep at least 20% free space to allow the automatic defragmentation to work efficiently. Multiple partitions will not help much as far as I can tell.

So I think you should use 1 partition per drive except when you have a very good reason to have more than 1 partition. I have 1 hard drive with multiple partitions and 7 hard drives with 1 partition. The partitionned hard drive (10 slices) holds MacOS 10.2.8, MacOS 10.3, MacOS 10.3.5, MacOS 10.3.9, MacOS 10.4, MacOS 10.4.9 and MacOS 10.5. The free partitions are used to copy install DVD instead of burning it per example.

Tom Boucher
2007-02-27 06:25:08
I got my boot drive down to 1GB the other week and it got really really cranky with me over night.

I have about 2GB of memory, i'm wondering if it's a swap thing.

Anyway for partitioning. I recently snagged 3 500GB drives and I just made one big stripe set out of them so I could have 1.4TB of disk space. Not a big fan of lots of hard drive icons on my desktop. Working fine so far.

2007-02-27 06:37:16
I was used to partition my drives until one crashed. If I hadn't partitionned it I could have saved all the data. Since then I never partition drives anymore, when I use big drives. Using 500Gb hard disk space to make looong and big video rendering, the ability to retreive data from a crashed HD can be really handy sometimes.
Robert 'Groby' Blum
2007-02-27 06:50:55
I can't really see a reason to partition your HD - unless you actually need different file systems. (I.e you're running Bootcamp. Or you're on the bleeding edge and want to try something like ZFS). Although I have to admit that I like the idea with the seven partitions - you could go crazy with the icons! ;)

If you do partition your HD, you will want to change partition sizes sooner or later. I've got to mention the fabulous iPartition here - saved my behind when playing with partitions till I had the space divided just right between Windows and OSX.

2007-02-27 07:29:26
I would just keep Time Machine in mind. Where and how you want Time Machine to store it's info.
2007-02-27 07:31:26
I don't like to use partitions either. I used to use them to define different access privileges, mount points, shares, backup routines, etc. for each partition but now I do all that with folders and it works out much cleaner with modern GUI tools like we have on OS X.

I partitioned one external drive so I could put a FAT32 partition on there to share files between Windows and OS X. The rest is HFS+ because I need large files (>4GB) on there too. That seems to be about the only reason to do it anymore. Once we get ZFS support in OS X and Windows (somebody will do it, right?) then I'll just use that everywhere.

2007-02-27 09:14:57
one big partition. no matter how good your guess is about OS/Apps vs. Data partition you'll never get it right. Advances in hardware and software have made the performance need for partitions obsolete.
2007-02-27 10:09:06
I always do 3 partitions. Two for OS, one for data.

With 2 OS partitions, I can replicate Known-Good to a Working partition, modify Working, and still have Known-Good to bail me out if Working goes walkabout.

Neither Software Updates nor Security Updates are perfect, and it's a lot easier to risk a duplicate than to risk everything. If the Working DOES work out, then it becomes the new Known-Good, and I duplicate it to the new Working for modification.

It's like a two-step process to anywhere, where you can always go back one step. The 2 OS partitions should be equally sized, but the data partition can be different.

Michael Maggard
2007-02-27 11:25:19
Partitioning is more cosmetic then anything these days. File systems are advanced enough, and how we use them complex enough, that nothing special "needs" to be done; it mostly comes down to how you like things organized.

That said how you back things up is much more the important issue. Having at least one external drive with a full backup of your current system will save you endless grief the day your primary drive dies (and they all do someday, usually the worst day.)

In my household no addt'l drive space gets added unless it is explicitly "temp" (and really is!) or there is a matching set of space for backing it up somewhere else. The number of times that has saved my bacon is astonishing (and very unnerving.)

Finally, paste a note on every external Firewire drive: "Unplug this when doing system updates!". For whatever reason external FW drives are a huge source of MacOS X update/upgrade issues, so just unlpug 'em when doing that occasional task.

David Battino
2007-02-27 11:34:57
Wow! Thanks, everyone. This is really valuable information. A follow-up question: Shall I use Disk Utility to set up the new drive or something fancier?

2007-02-27 14:20:34
KISS. Keep It Simple Stupid. I used to use partitions, but I agree with the others, unless you need different systems, use folders. I'd probably install a system on the new disk. Should you migrate to it and make it your primary drive? Read migration arrticles to decide if you're better off starting from scratch (migrate your basic connection settings and reinstalling everything) on your new drive. After a few weeks you might copy all your files to your new drive and then erase the smaller drive and use it as a backup or place to keep big collections (photos, music, whatever takes up big chunks of space).

Probably a good time to ask if Leopard is going to change anything.

2007-02-27 15:18:17
I have one partition on my internal disk, but two partitions on the external Firewire disk; one is general-purpose, and the other is a "Work" partition for audio recording. I like the idea of being able to erase the partitiion and get contiguous space for laying down tracks -- though, as I think about it, I've never tested to see if it makes a difference. I only use "Work" for the actual recording, and move the tracks to the general purpose partition once the live tracking is done.
Skip Steuart
2007-02-27 19:38:25
I like putting a small bootable partition onto each drive just in case.

Things have been so stable lately I may stop doing that.

2007-02-27 20:03:08
Opinionsmay - and do - vary, but I have at least 2 and normally 3 partitions. The first for system files, the second for my home directory and files and sometimes a third for storage. Reason? - I can reformat, update whatever the system partition WITHOUT having to to reconfigure my laboriuosly concocted home. Back up the home partition and redo the system partition at will. PLUS - most fluctuating changes happen on the system partition and when it goes bad, which it will, I have only to reinstall OSX and things are just peachy! (plus the 'few' applications insisting on the main directory for installation).



Lee Joramo
2007-02-28 06:56:38
These days I only partition my notebooks. One large main partition, and one small emergency boot & utility partition. If my main partition has a problem and Disk Utilities or Disk Warrior can not repair it while it is the boot partition, I can use the emergency partition.

On desktops, I allows have access to the utility CD/DVD or to an external firewire drive.

2007-02-28 10:04:20
Perhaps two partitions - one which is very small. I did that ages ago, and now use the small partition for the swap files. The logic being that they won't fragment or run out of space. Whether that's true logic or pretzel logic, I'm not sure.