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Old Nov 7, 2012, 04:13 AM   #1
seniorchang
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Disable Fusion Drive

Do you think it will be possible to disable fusion drive and manually manage the 128 GB / 1TB drives as two volumes?
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Old Nov 7, 2012, 04:22 AM   #2
leman
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Yes, it will be most certainly possible using the diskutil command-line utility. However, the automatic tiered storage will almost always do a better job than manual management (as it works per block instead of per-file), unless you have some very specific needs.
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Old Nov 7, 2012, 04:27 AM   #3
squan
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They have been able to get Fusion Drive working on other SSD-HD combos, but with some heavy tinkering in Terminal. So the opposite could be possible to, with the same amount of effort.

But probably not something you wanna do in a couple of minutes of sparetime...
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Old Nov 7, 2012, 04:47 AM   #4
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Was also wondering this as I like to split the SSD between my osx and windows partition. I wonder how fusion copes with bootcamp?
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Old Nov 7, 2012, 04:50 AM   #5
initialsBB
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Bootcamp is reported as working but only places the Windows partition on the HDD.
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Old Nov 7, 2012, 09:51 AM   #6
theturn
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Originally Posted by initialsBB View Post
Bootcamp is reported as working but only places the Windows partition on the HDD.
on fusion drive that is, if you delete the logical volume group and install osx on the ssd directly I'm sure bootcamp will let you partition it to install windows.
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Old Nov 7, 2012, 11:34 AM   #7
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Quote:
Originally Posted by squan View Post
They have been able to get Fusion Drive working on other SSD-HD combos, but with some heavy tinkering in Terminal. So the opposite could be possible to, with the same amount of effort.

But probably not something you wanna do in a couple of minutes of sparetime...
All it takes is 2 commands in diskutil to set up a "Fusion" drive ... and it takes less than 2 minutes!

There are also "undo" commands which will un-join the Fusion drive and revert the drives back to normal so they can be managed manually.

----------

Quote:
Originally Posted by ninja2000 View Post
Was also wondering this as I like to split the SSD between my osx and windows partition. I wonder how fusion copes with bootcamp?
I have done this on my 2011 Mac Mini which already had the SSD partitioned for Windows and OS X as well as a hard disk data drive.

It is true as Apple has said that you can't create a SSD BootCamp partition on a fusion drive, as it will always put it on the hard disk.

However, if you already have the partition created on the SSD and then build the "Fusion" drive, it will keep it there and it works fine.

There is another thread here which discusses the Fusion drive in more detail.

This is my disk layout after the fusion drive was created:

Code:
/dev/disk0
  #:                       TYPE NAME                    SIZE       IDENTIFIER
  0:      GUID_partition_scheme                        *240.1 GB   disk0
  1:                        EFI                         209.7 MB   disk0s1
  2:          Apple_CoreStorage                         158.8 GB   disk0s2
  3:                 Apple_Boot Recovery HD             785.0 MB   disk0s3
  4:       Microsoft Basic Data Windows SSD             80.2 GB    disk0s4

/dev/disk1
  #:                       TYPE NAME                    SIZE       IDENTIFIER
  0:      GUID_partition_scheme                        *500.1 GB   disk1
  1:                        EFI                         209.7 MB   disk1s1
  2:          Apple_CoreStorage                         499.8 GB   disk1s2
  3:                 Apple_Boot Boot OS X               134.2 MB   disk1s3

/dev/disk2
  #:                       TYPE NAME                    SIZE       IDENTIFIER
  0:                  Apple_HFS Macintosh Fusion       *655.5 GB   disk2

Last edited by hfg; Nov 7, 2012 at 11:13 PM.
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Old Nov 8, 2012, 04:48 AM   #8
squan
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Quote:
Originally Posted by hfg View Post
All it takes is 2 commands in diskutil to set up a "Fusion" drive ... and it takes less than 2 minutes!

There are also "undo" commands which will un-join the Fusion drive and revert the drives back to normal so they can be managed manually.
Ha ok then! Looks like progress has been made since last time I read about it... Very nice option.
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Old Nov 15, 2012, 12:10 PM   #9
dography
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Hi all,

I just bought a new Mac Mini, installed an SSD in addition to the 1TB HDD that came with it, as soon as I opened disk utility, it merged the drives, exactly what I didn't want...! Can't seem to find a solution anywhere to reverse the fusion of the drives, anyone have a link or some advice? I assume it is possible?
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Old Nov 15, 2012, 12:50 PM   #10
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Yes, it is easy to separate the drives and revert them back to normal SSD and HD drives. It does require using a couple of Terminal commands at this time. Future upgrades may add that function to Disk Utility to make it easier. If you look at the threads on this forum for creating "Fusion" drives on older computers, you will see the Terminal commands used and there are additional commands to undo those operations.

You will have to restore all your data, so make sure you have a good backup before you start.

On the second page of this article is even shows the steps necessary to revert a Fusion drive back into the native drives:
http://arstechnica.com/apple/2012/11...-fusion-drive/

In my experimentation with "Fusion" on a Mac Mini and MacBook Pro I have built, broken, and re-built the Fusion drives several times for different configurations.



-howard

The required commands are:
(note: you can use diskutil list and diskutil cs list to obtain the volume ID's on your computer)

diskutil cs deleteVolume < insert fusion logical volume ID here >
diskutil cs delete < insert coreStorage logical volume group ID here >



...

Last edited by hfg; Nov 15, 2012 at 08:14 PM. Reason: added command info
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Old Nov 15, 2012, 03:34 PM   #11
kgian
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Hopefully someone will create a utility to automate such tasks.
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Old Nov 15, 2012, 05:16 PM   #12
hfg
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Quote:
Originally Posted by kgian View Post
Hopefully someone will create a utility to automate such tasks.
It's only a couple of commands ...

But it will probably be included in Disk Utility sometime soon.

The required commands are:
(note: you can use diskutil list and diskutil cs list to obtain the volume ID's on your computer)

diskutil cs deleteVolume < insert fusion logical volume ID here >
diskutil cs delete < insert coreStorage logical volume group ID here >

Last edited by hfg; Nov 15, 2012 at 07:39 PM.
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Old Nov 15, 2012, 07:21 PM   #13
dography
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Howard, appreciate the assistance.

Do you think I would see a noticeable difference in performance if I separated the drives and installed OS X (and all other apps) on the SSD (leaving the HDD blank for storage only) or will OS X manage this 'fusion' drive effectively enough (even though it's not an official fusion drive shipped by Apple) that I will notice little difference? As I said, I'm not particularly familiar with Terminal but the link you provided seems to be only 3 lines of code in terminal to fix (I'm happy to reinstall OS X if needs be).

I also stumbled across Trim Enabler, apparently required (or at least highly recommended) for SSD drives installed other than by Apple. Would this still be necessary if OS X is now managing my HDD/SDD as if were a normal fusion drive? I understand it's for prolonging the life of the drive through read/write cycles or something, haven't actually used it yet.

Excuse the ignorance, it's my first foray into deviating from the standard fare offered by Apple, just trying to ensure I make the most of the extra bit of money I've spent tweaking...!

Thanks again
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Old Nov 15, 2012, 07:46 PM   #14
dography
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Missed your last response before I posted but yes, seems to be just those two commands, the volume / volume group IDs for which I can see using the two diskutil commands you mentioned below so I can manage that, just curious as to whether it's worth the effort of reinstalling for a potentially negligible (or even detrimental) performance improvement.
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Old Nov 15, 2012, 08:05 PM   #15
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Quote:
Originally Posted by dography View Post
Howard, appreciate the assistance.

Do you think I would see a noticeable difference in performance if I separated the drives and installed OS X (and all other apps) on the SSD (leaving the HDD blank for storage only) or will OS X manage this 'fusion' drive effectively enough (even though it's not an official fusion drive shipped by Apple) that I will notice little difference? As I said, I'm not particularly familiar with Terminal but the link you provided seems to be only 3 lines of code in terminal to fix (I'm happy to reinstall OS X if needs be).

I also stumbled across Trim Enabler, apparently required (or at least highly recommended) for SSD drives installed other than by Apple. Would this still be necessary if OS X is now managing my HDD/SDD as if were a normal fusion drive? I understand it's for prolonging the life of the drive through read/write cycles or something, haven't actually used it yet.

Excuse the ignorance, it's my first foray into deviating from the standard fare offered by Apple, just trying to ensure I make the most of the extra bit of money I've spent tweaking...!

Thanks again
If everything on your computer will comfortably fit on the SSD only, they you really don't need the "Fusion" functionality at this time. If you are storing library data on the hard disk that you actively reference in your day-to-day usage, that data will all be accessed at hard disk speeds if they are separate.

If you enable the Fusion drive functionality, then any small elements within the hard disk library that you are actively working on (multiple accesses) will be moved to the SSD on the second access. The initial access to that data will be at hard disk speeds, subsequent access will be very fast. It isn't the entire library, or even the entire file that will be moved, only the parts that you are using.

Others have provided suggested examples here ... such as a game with many levels ... the level you are playing will be on the SSD, and the levels you have completed will be back on the hard disk, along with future levels you haven't reached yet. You can't manually duplicate that kind of granularity!

Obviously, to the users here, this is all new and there isn't enough actual experience to know all the answers, but the concept is exciting and I think worth playing with until SSD prices come down to where large SSD systems are affordable and we can dispense with work-flow hard disks altogether.

There are several discussions regarding trim on these forums ... the consensus seems to be that trim is desirable with most brands of SSD, even when running a fusion drive. I wouldn't worry about wearing out the SSD, the cycle counts on modern SSDs should far exceed your usage during the useful life of the computer. Do keep a rigorous backup however ... both SSD and hard disks do fail and you don't want your precious data to be a casualty.


-howard
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Old Nov 16, 2012, 05:22 PM   #16
dography
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Thanks again Howard. To be honest I didn't need the HDD that came with it as I store all my files on external drives. I appreciate that these are the weak link speed-wise but the least I can do is have the OS and apps on SSD for startup etc (the HDD I can then use for overflow). I'll get terminal running and delete the volume group. One last question..I will obviously see the disk utility error next time I open it (after reverting) that will try to force me to fuse them again, I assume just quitting at this point will cause no problems or do I need to refrain from ever using disk utility again?
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Old Nov 16, 2012, 07:26 PM   #17
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Quote:
Originally Posted by dography View Post
Thanks again Howard. To be honest I didn't need the HDD that came with it as I store all my files on external drives. I appreciate that these are the weak link speed-wise but the least I can do is have the OS and apps on SSD for startup etc (the HDD I can then use for overflow). I'll get terminal running and delete the volume group. One last question..I will obviously see the disk utility error next time I open it (after reverting) that will try to force me to fuse them again, I assume just quitting at this point will cause no problems or do I need to refrain from ever using disk utility again?
I don't have one of the new machines which came with Fusion and thus with the newer version of Disk Utility. However, if your drives are not cast as "coreStorage" type, I would hope that Disk Utility would leave them alone! That will irritate a lot of people who desire separate drives if they are continually nagged to repair the Fusion drive.

With respect to your system and data requirements ... I too want all my stuff on the SSD, but for me it is too much. Sounds like you can fit all of your requirements onto the SSD at this time ... so, even if you left the Fusion drive intact, all your data would still reside on the SSD and your hard disk would remain empty until such time as the SSD became close to full. Your system performance would equal that of separate drives, and only when you exceeded the SSD capacity would the Fusion functionality go into effect, and it would be seamless and automatic such that you probably wouldn't even notice it.

Either way you end up configuring it, I am sure you will be happy with the results and with your new computer.


-howard
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Old Nov 17, 2012, 07:15 AM   #18
mogens
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Great info here thanks. I've succesfully created a fusion drive using the internal 2Gb HDD and a samsung 830 256Gb disk in the optical bay. Would it be safe to enable Trim after the drive has been created? Is there a command in Terminal to see the SSD trim status ?
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Old Nov 17, 2012, 10:44 AM   #19
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Originally Posted by mogens View Post
Great info here thanks. I've succesfully created a fusion drive using the internal 2Gb HDD and a samsung 830 256Gb disk in the optical bay. Would it be safe to enable Trim after the drive has been created? Is there a command in Terminal to see the SSD trim status ?
You can run the trim enabler that is widely discussed here on the forum. You can see the status of trim by looking at your system profile reached from "AboutThisMac". From the list select "Serial-ATA" and locate your SSD. About half way down the drive information you will see "TRIM Support" which will show either Yes or No. If it says YES, then you are good to go!


-howard
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Old Dec 13, 2012, 04:49 AM   #20
torana355
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Originally Posted by hfg View Post
The required commands are:
(note: you can use diskutil list and diskutil cs list to obtain the volume ID's on your computer)

diskutil cs deleteVolume < insert fusion logical volume ID here >
diskutil cs delete < insert coreStorage logical volume group ID here >



...
Hi i just wanted to know where you find the "fusion logical volume ID"? I know where the corestorage logical volume is by using "diskutil cs list"
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Old Dec 13, 2012, 09:44 AM   #21
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Originally Posted by torana355 View Post
Hi i just wanted to know where you find the "fusion logical volume ID"? I know where the corestorage logical volume is by using "diskutil cs list"
If you look at the results of "diskutil cs deleteVolume", both IDs are there.

diskutil cs deleteVolume
Usage: diskutil coreStorage deleteVolume lvUUID
Delete a logical volume. The volume must be unlocked.
Example: diskutil coreStorage deleteVolume 11111111-2222-3333-4444-555555555555


Here is what I get on this computer:


Code:
diskutil cs list
CoreStorage logical volume groups (1 found)
|
+-- Logical Volume Group DA960F9B-8DC0-43B8-836B-C1D04DB1AC8B
    =========================================================
    Name:         Fusion
    Size:         3255449763840 B (3.3 TB)
    Free Space:   55054770176 B (55.1 GB)
    |
    +-< Physical Volume 9BC3D042-FFB2-426D-95E1-B61B5D6B7914
    |   ----------------------------------------------------
    |   Index:    0
    |   Disk:     disk0s2
    |   Status:   Online
    |   Size:     255716540416 B (255.7 GB)
    |
    +-< Physical Volume 3107BBDB-B5E3-40F4-AD95-F1FC3E20F447
    |   ----------------------------------------------------
    |   Index:    1
    |   Disk:     disk5s2
    |   Status:   Online
    |   Size:     2999733223424 B (3.0 TB)
    |
    +-> Logical Volume Family 6605C39A-1C2F-48A6-9E53-6F0D0285342D
        ----------------------------------------------------------
        Encryption Status:       Unlocked
        Encryption Type:         None
        Conversion Status:       NoConversion
        Conversion Direction:    -none-
        Has Encrypted Extents:   No
        Fully Secure:            No
        Passphrase Required:     No
        |
        +-> Logical Volume 118CBB57-7DF4-4695-A728-E3B36B4E3D2F
            ---------------------------------------------------
            Disk:               disk8
            Status:             Online
            Size (Total):       3189484273664 B (3.2 TB)
            Size (Converted):   -none-
            Revertible:         No
            LV Name:            Fusion
            Volume Name:        Fusion
            Content Hint:       Apple_HFS
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Old Dec 13, 2012, 02:13 PM   #22
Khadgar
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Where exactly are you expected to do this from? From an external bootable drive?

I would need to install OS X after this is over with, so how exactly would I go about that? My USB stick doesn't work on this new iMac, and I can't download Mountain Lion from the App Store either.
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Old Dec 13, 2012, 02:20 PM   #23
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Originally Posted by Khadgar View Post
Where exactly are you expected to do this from? From an external bootable drive?

I would need to install OS X after this is over with, so how exactly would I go about that? My USB stick doesn't work on this new iMac, and I can't download Mountain Lion from the App Store either.
Yes, or course, you do need to be booted from an external or USB Install thumb drive if your are altering your Fusion drive.

When either creating, or breaking, the Fusion drive, all involved partitions will be reformatted. Thus you need to do a full backup, then do your Fusion operation (takes a minute for this), then do a restore from your backup (or perform a fresh install from a thumb-drive install or from Apple over the internet) and use Migration Assistant to restore your desktop environment).

Easiest may be to clone to external drive, boot external drive and do Fusion manipulation, then clone external back to work drive(s).
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Old Dec 13, 2012, 02:21 PM   #24
Khadgar
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Ahh crap. I forgot about the online download. I came from a 2006 computer, so some of this new stuff hasn't been ingrained in my memory. Thanks for the help.
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Old Dec 13, 2012, 03:35 PM   #25
Khadgar
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I attempted this on my new iMac and it won't allow it to reinstall the system unless you allow it to fuse the drives.
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