Issue Creating a 2nd Partition on Fusion Drive

[jedib0p]

I was wondering if anyone else has had issues creating a 2nd partition on the fusion drive. When I choose the size the partition ends up being far larger than the size I had selected. (Example: I choose 80GB for the partition and when the resize operation is completed it is 270GB instead.)

I've tried partitioning the drive in OS X and while booted into the recovery partition.

[MatthewAMEL]

What are you using to attempt to create the partition?

Currently, only the version of Boot Camp Assistant and Disk Utility that ship with the new Mini or iMac support Fusion Drive in the GUI.

[jedib0p]

I have a 2012 Mac Mini and I'm using Disk Utility GUI.

[scottyd1119]

I tried this last night as well using the gui version of disk utility. The only thing that it would allow me to do was create a new partition that was half of the original. I had no control over the size. I tried this and basically ended up with half the space available. The new partition I created for all intense and purposes evaporated into thin air. I went into terminal and used command diskutil list. It showed that I had a second partition. I didn't go any further, not feeling comfortable running any commands to get it to show. I ended up just splitting the core storage and creating two drives out of the fusion. I like the idea of the fusion drive but was hoping to partition the 1tb drive to allow some control over where files were stored, i.e. wanted to put all my pictures, movies, music, etc on a separate volume because they don't need speed increase of the ssd.

I would love to see if anyone does figure out a way to partition the platter drive because I might re-fuse the drives and go that route.

[jedib0p]

I found that when creating the 2nd partition you are not able to enter a size numerically but you can however drag the space between the 2 partitions to decrease/increase its size.

The problem for me is that the size shown after dragging is much much different than what is created when applying the new partition.

[scottyd1119]

Did your new partition show up as a separate volume and were you able to access it?

[jedib0p]

Yes. I had no problem creating the new volume and could access it fine. The only issue is it isn't sizing correctly. I want to make a partition that is ~150GB but even choosing (by dragging) a partition size of 65GB (the smallest i could select) when the process is complete the partition would be 270GB.

I created and deleted the 2nd partition using various sizes several times and the result was always the same. The created partition would end up being ~200GB larger than what I selected.

[MJL]

Enquiring mind likes to know:

This 65 Gb / 270 Gb partition: is that the resized original partition or is it the new partition?

How large is your SSD?

Can it be that the whole SSD forms the Fusion partition with a small part of the HHD and that the other partition is only a part of the HDD without a part of the SSD?

Thanks!

edit: I suppose http://support.apple.com/kb/HT5446?v...S&locale=en_US goes a long way to answering the questions I have.

[jedib0p]

Originally Posted by MJL

Enquiring mind likes to know:

This 65 Gb / 270 Gb partition: is that the resized original partition or is it the new partition?

How large is your SSD?

Can it be that the whole SSD forms the Fusion partition with a small part of the HHD and that the other partition is only a part of the HDD without a part of the SSD?

Thanks!

edit: I suppose http://support.apple.com/kb/HT5446?v...S&locale=en_US goes a long way to answering the questions I have.

This is an Apple official Fusion Drive. Not a DIY. It has a Samsung 830 128GB SSD and a Hitachi 1TB 5400rpm HDD.

I've taken a few screenshots to show what's going on. As you can see in the picture the 2nd partition is showing 67.3GB. All other space is shown as being allocated to the primary Fusion partition.

Here's an output of the Log file shown what actually happens when applying it as shown.

2012-12-01 15:41:49 -0400: Disk Utility started.

2012-12-01 15:42:25 -0400: Preparing to partition disk: “APPLE HDD HTS541010A9E662 Media”
2012-12-01 15:42:26 -0400: Checking prerequisites for resizing Logical-Physical volume stack
2012-12-01 15:42:26 -0400: Shrinking Logical-Physical volume stack
2012-12-01 15:42:26 -0400: Checking file system
2012-12-01 15:42:26 -0400: Performing live verification.
2012-12-01 15:42:26 -0400: Checking Journaled HFS Plus volume.
2012-12-01 15:42:26 -0400: Checking extents overflow file.
2012-12-01 15:42:26 -0400: Checking catalog file.
2012-12-01 15:42:51 -0400: Checking multi-linked files.
2012-12-01 15:42:51 -0400: Checking catalog hierarchy.
2012-12-01 15:42:51 -0400: Checking extended attributes file.
2012-12-01 15:42:51 -0400: Checking volume bitmap.
2012-12-01 15:42:51 -0400: Checking volume information.
2012-12-01 15:42:51 -0400: The volume Fusion HD appears to be OK.
2012-12-01 15:42:51 -0400: Shrinking file system
2012-12-01 15:42:51 -0400: Shrinking Logical Volume
2012-12-01 15:42:51 -0400: Resizing Core Storage Logical Volume structures
2012-12-01 15:42:52 -0400: Resized Core Storage Logical Volume to 837076029440 bytes
2012-12-01 15:42:52 -0400: Shrinking Core Storage Physical Volume from 999345127424 to 724594659328 bytes
2012-12-01 15:42:52 -0400: Shrinking Core Storage data structures
2012-12-01 15:42:52 -0400: Resizing Core Storage Physical Volume structures
2012-12-01 15:42:54 -0400: Resized Core Storage Physical Volume to 724594659328 bytes
2012-12-01 15:42:54 -0400: Copying booter
2012-12-01 15:43:17 -0400: Shrinking partition for Physical Volume and adding new partitions
2012-12-01 15:43:17 -0400: Modifying partition map
2012-12-01 15:43:22 -0400: Initialized /dev/rdisk1s4 as a 256 GB HFS Plus volume with a 24576k journal

2012-12-01 15:43:22 -0400: Mounting disk
2012-12-01 15:43:22 -0400: Partition complete.
2012-12-01 15:43:22 -0400:

So that 67.3GB volume becomes 256GB. I haven't been able to make it any smaller than that. The primary volume loses the appropriate amount of space and the total amount of storage over the 2 volumes is still 1.12TB.

[chrise2]

I thought you were only supposed to use the Boot Camp assistant to create the partition on a Fusion drive. Maybe delete that partition and try again?

[jedib0p]

In case anyone is curious I worked around this issue using command line tools while booted in to the Recovery Partition.

I started with a single Fusion Drive partition (aside from Recovery HD and EFI partitions) and then used the command:

diskutil cs resizeStack

It allows you to perform a shrink (or grow) operation on the LVG, specify which PV is reduced and partition the newly created space in 1 or several partitions.

This allowed me to specify the size I wanted for my 2nd partition and actually get the correct size.

[cingularpat]

jedib,

How did you use this command? I tried it using the UUID of my Fusion drive and it says it's invalid. Can you shed some light on the proper verbiage for the command??

Originally Posted by jedib0p

In case anyone is curious I worked around this issue using command line tools while booted in to the Recovery Partition.

I started with a single Fusion Drive partition (aside from Recovery HD and EFI partitions) and then used the command:

diskutil cs resizeStack

It allows you to perform a shrink (or grow) operation on the LVG, specify which PV is reduced and partition the newly created space in 1 or several partitions.

This allowed me to specify the size I wanted for my 2nd partition and actually get the correct size.

[Fishrrman]

If I start out with a fusion drive (128gb SSD + 1tb HDD), can I do the following?

1. Manually "un-fuse" the two drives (yes, I know this can be done), then...

2. PARTITION the 1tb HDD drive into, say, 4 separate partitions (256gb each), then...

3. RE-fuse ONE of the partitions with the SSD drive.

The results should appear on the desktop as:
- fusion drive (SSD + HDD)
- another partition
- another partition
- another partition
(4 disk icons, total)

??

[jedib0p]

Originally Posted by cingularpat

jedib,

How did you use this command? I tried it using the UUID of my Fusion drive and it says it's invalid. Can you shed some light on the proper verbiage for the command??

Here's the output from the diskutil command:

diskutil coreStorage resizeStack lvUUID [pvUUID] size
[part1Format part1Name part1Size part2Format part2Name part2Size
part3Format part3Name part3Size ...]

the lvUUID I think was the last number that comes up when you do a "diskutil cs list" (it may have been the LVG UUID but if you put the wrong one it will just give an error and you can change it to the correct one). The pvUUID is an optional command to specify which physical disk is reduced when the command is carried out. This is useful to insure the space is resized on the HDD rather than the SSD.

In my case my original Fusion Drive was 1.12TB and I wanted to create a partition that was 120GB on the HDD (turning the fusion into roughly 1.0TB). I basically compared the sizes from the diskutil list command to determine what the before and after sizes should be.

Here's a screenshot to show you what numbers I used.

Obviously you would need to use your own UUIDs but here's what my command looked like:

diskutil cs resizeStack B76211F4-4A5B-44FB-AC5B-8CCE361CADA2 CC0F89BF-4A19-4442-B273-933AF6D772C1 991G jhfs+ Media 120G

991G is the size I want my Fusion Drive to be post operation.
"jfhs+ Media 120G" specifies I want to create a 120GB journaled HFS+ volume named Media.

I'm going from memory here but hopefully that is clear enough for you.

[jedib0p]

Originally Posted by Fishrrman

If I start out with a fusion drive (128gb SSD + 1tb HDD), can I do the following?

1. Manually "un-fuse" the two drives (yes, I know this can be done), then...

2. PARTITION the 1tb HDD drive into, say, 4 separate partitions (256gb each), then...

3. RE-fuse ONE of the partitions with the SSD drive.

The results should appear on the desktop as:
- fusion drive (SSD + HDD)
- another partition
- another partition
- another partition
(4 disk icons, total)

??

1. You shouldn't need to "un-fuse" the Fusion Drive. You can use the same command that I specified above.

Determine the sizes of partitions that are present on the HDD currently and the sizes of the new partitions you want to add.

So for example you currently have the corestorage volume and a recovery HD volume. You want to create 3 new partitions each 150GB (450GB total removed from the corestorage volume) in size on the HDD. Use the command as such:

diskutil cs resizeStack lvUUID pvUUID 660G jhfs+ Volume1name 150G jhfs+ Volume2name 150G jhfs+ Volume3name 150G

660G is a rough guess at the size of the Fusion volume (~540GB on HDD + 120G SSD) Adjust the sizes to your specific needs.

[cingularpat]

jedib0p, that worked perfectly! Thank you for explaining!!

[iKenny303]

jedib0p, if the fusion partition already has Mt Lion and user data on it, is it erased by this process of creating the 2nd partition?

[jedib0p]

The resizeStack command is non-destructive so no, your data will not be erased. Of course, you should always backup just in case.

[cingularpat]

While my resize procedure worked great, I was doing this for the purpose of making a Bootcamp partition. Unfortunately, Windows just wouldn't install on it. I'm thinking there's too many partitions on the HDD for Windows to be happy.

[jedib0p]

Originally Posted by cingularpat

While my resize procedure worked great, I was doing this for the purpose of making a Bootcamp partition. Unfortunately, Windows just wouldn't install on it. I'm thinking there's too many partitions on the HDD for Windows to be happy.

Did you format as jhfs+ or fat32 or ntfs? It would need to be a compatible volume for you to install windows.

Any reason you didn't just use the boot camp assistant?

[cingularpat]

Formatted as FAT32 during the resize, and then let the Windows Installer reformat as NTFS. I tried the Bootcamp assistant, but it wouldn't recognize my flash drive with the Windows Installer on it, even though it boots fine when holding Alt down during startup. So I could never get to the actual re-formatting of the drive.