Disk Utility - smallest partition size

Question

Disk Utility - smallest partition size

I have new 500 GB external drive. Using Disk Utility I created GUID partition schema and created 4 partition - 3 x Mac OS Extended (Journaled) a 1 x FAT32 (initially with same size). Disk Utility doesn't let me resize 1st partion (the highest one) and 4th partition (the lowest one) smaller then cca. 50 GB (divider with 2 arrows changed to divider with 1 arrow). (I don't know if it's possible with other partitions to size them smaller then cca. 50 GB since I want them have large and I use disk already.) I didn't find anything about this in help, books or internet.

Is there limit in Disk Utility about minimum partition size? (It looks like cca. 10 % from drive size).

MacBook, 2.4 GHz Intel C2D, 2 GB RAM, Mac OS X (10.5.4)

Posted on Jul 30, 2008 11:24 AM

Reply

Answer 1

Glynn

Level 4

1,375 points

Jul 30, 2008 11:40 AM in response to Community User

Hello there, Disk Utility will not change a single partition without affecting all of the others. To do that you will need to start in single-user-mode or from the install disc. Mount the drive in single-user-mode or use terminal from the disc.

The command you need to look at is:
diskutil resizeVolume

Here is the man page:
http://developer.apple.com/documentation/Darwin/Reference/ManPages/man8/diskutil .8.html

I suggest you google diskutil and search these forums for people that have done this. Here is on to start with...

http://www.macgeekery.com/tips/cli/nondestructivelyresizingvolumes

Good Luck and Cheers,
Glynn

Reply

Answer 2

nerowolfe

Level 6

13,090 points

Jul 30, 2008 11:43 AM in response to Community User

Welcome to the Apple boards.
It's possible on a 500 GB drive, that the smallest partition size is limited on purpose by the Disk Utility.
The bare filesystems themselves take up a good deal of space.
You might be able to create a smaller partition with 3rd party SW, but be careful when mixing things on a single drive.
I would not play around with any HD that was intended for use with TM, other than creating another HFS+ partition for separate storage.

Reply

Answer 3

V.K.

Level 9

56,174 points

Jul 30, 2008 11:52 AM in response to Community User

it looks like DU will not allow you to create a partition smaller than one tenth of the disk size.
when i do it on a 200GB drive the smallest size it let's me make is 20Gb, and for a 500GB drive it's 50GB.

I guess that's a safeguard against creating too many partitions.

Message was edited by: V.K.

Reply

Answer 4

V.K.

Level 9

56,174 points

Jul 30, 2008 11:55 AM in response to Glynn

you can't run diskutil in single user mode in leopard. at least nobody has figured out how to do it yet.

Reply

Answer 5

nerowolfe

Level 6

13,090 points

Jul 30, 2008 12:03 PM in response to V.K.

V.K. wrote:
it looks like DU will not allow you to create a partition smaller than one tenth of the disk size.
when i do it on a 200GB drive the smallest size it let's me make is 20Gb, and for a 500GB drive it's 50GB.

I guess that's a safeguard against creating too many partitions.

Message was edited by: V.K.

I thought so. Like most filesystems, all the information must be stored in the bootsector or whatever it's called with BSD, and the total number of files is related to the sizes and total numbers of partitions, so like FAT32 or even NTFS, HFS has it's practical and theoretical limits.
I believe HFS has two bootrecords or equivalents, one for backup and this adds to the storage space issue.

Going back to the old 1.44MB floppies, the unformatted size was over 1.7 MB and Norton and MS took advantage of that, but not all disk readers were happy with what they did. MS once shipped Windows on a set of 1.7 MB floppies. Of course this was BC (before CDs).

Reply

Answer 6

Jul 30, 2008 2:05 PM in response to V.K.

Since V.K. has similar experience I agree with him/her that Disk Utility will not allow to create a partition smaller than one tenth of the disk size. Good to know for future.

Reply

Answer 7

Aug 7, 2008 10:15 PM in response to Community User

Almost, my LaCie 149.1GB Firewire external has 5 partitions
12.06 GB Leopard 10.5.4
11.55 GB PPC Tiger 10.4.11
9.24 GB Tiger image
11.31 GB Leopard image
104.28 GB Data

I tried to make the first 4 partitions as small as possible, and they are the sizes disk Utility gave me, so it's not 10%, but I don't know how it decides.

Mark

Reply

Answer 8

Aug 7, 2008 10:22 PM in response to Community User

You should be able to create partitions of pretty much any size. Perhaps for clarity in the volume diagram Disk Utility limits the size that can be determined by dragging the volume separator bar. However, you can select the desired partition and then over on the side locate the input field labeled "Size". You can then enter another number (in GB) and create a partition of that size. If you create a smaller partition that what can be displayed in the volume diagram, an asterisk will appear next to the volume name which indicates the volume is smaller than what is displayed.

Reply

Answer 9

Aug 7, 2008 10:37 PM in response to MarkCramer

And testing a bit more, if you create a partition and then manually specify the size (ie type in the box), it lets you create smaller partitions. I just resized my data partition and created 8G and 2G partitions at the end of the disk.

So ~10% using the GUI, and smaller if you specify.

Reply