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Mountain Lion installation on home built Fusion Drive System 10.8
Inspired by an Jinx's article about building your own fusion drive I've decided to take it one step further and brew my own with full OS X installation on it.

First, I needed to put two drives in my Mac. I already had a Crucial M4 SSD and 500GB HD so I a bought hard drive caddy and put my 500GB Momentus XT in it.

That was the easy part. Now how to make them work? In Jinx's article you can read that GUI Disk Utility does not offer needed functionality. It's available only in command line version, diskutil. But from my previous installation I remembered that there is access to terminal in OS X's recovery mode.

It was downhill from there. Create a logical volume group, get the UUID and create the volume. The OS X Installer recognized the volume and installed nicely. After the whole process was over, I did tests similar to those that Jinx mentioned and the drive does, indeed, behave like a fusion drive - files used more often end up on the SSD and less used are shuffled to the HDD.

You can see screenshots and more information here: Mountain Lion on home made Fusion drive

[kirkmc adds: I don't usually run hints that don't explain things, but the first article linked above goes into great detail. I'm tempted to try this out, as my Mac mini has both an SSD and a 750 GB HD, but I'd need to move all the files - my music collection - from the HD to an external drive. I might try and get to it this week.]
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Mountain Lion installation on home built Fusion Drive
Authored by: herothedog on Nov 05, '12 08:16:57AM

+1, did this to my 2009 MacBook Pro last week and it seems to work as described in the original article.



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patience
Authored by: lowbatteries on Nov 05, '12 08:19:43AM

Once the new iMacs ship sometime this month, I think we will see GUI support for this. I'm exciting about using an OWC data doubler on my MacBook and having a Fusion Drive, but I can wait until we know more.



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Mountain Lion installation on home built Fusion Drive
Authored by: dfbills on Nov 05, '12 08:29:46AM

I wonder how long it will be before someone releases an app to enable this using a GUI interface...

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-d



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Fusion Drive downside
Authored by: gabester on Nov 05, '12 08:40:40AM

One thing that I'm surprised we haven't seen more mention of is what I believe to be a downside of the Fusion drive. I have an SSD and HDD installed in my MBP. However, almost everything I need regular access to is on the SSD. The stuff on the HDD is mostly backup, archival, or occasionally accessed.

As such I regularly spin down the HDD to avoid the noise and power usage (I am still working on a better solution than periodically mounting via Disk Utility and unmounting via the Finder to spin it down). I am assuming that with Fusion drive the HDD would almost always remain on.

If Fusion Drive automatically manages the HDD spinup/down then that would be great... but I imaging the HDD will be left spinning all or almost all the time.
g=



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Fusion Drive downside
Authored by: agentx on Nov 05, '12 09:09:34AM

You are right the power management part in laptops is the bit we are all not sure about ;-)

I have a 512Gb SSD and a 750GB SSD/HDD combo in mine and i often unmount the HDD.
Also there are glaring issues as far as HFS+ corruption when will Apple sort that out....maybe never....

I am unsure if Diskwarrior works on Fusion drives !

Edited on Nov 05, '12 09:14:37AM by agentx



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Mountain Lion installation on home built Fusion Drive
Authored by: g3power on Nov 05, '12 09:40:03AM

Any idea what kind of caddy Tomasz is using?



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Mountain Lion installation on home built Fusion Drive
Authored by: dombi on Nov 05, '12 10:15:18PM

I am also wondering about one thing with the Fusion Drive. What happens if either one of the drives fail? Let's say the HDD fails.

Can you start your Mac at all?
How does the recovery procedure look like with the Fusion Drive?



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Mountain Lion installation on home built Fusion Drive
Authored by: spinkb on Nov 06, '12 01:52:01AM

Its "one drive"...so if part fails, its all broken. You need time machine keeping backups so you can replace the broken part, and recreate the drive structure, and restore again.



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Mountain Lion installation on home built Fusion Drive
Authored by: dombi on Nov 06, '12 02:24:13AM

Well, that kind of makes is difficult to deal with. Especially for users who are not so advanced.
I imagine that the same is true if you want to upgrade the HDD to a larger one.



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Mountain Lion installation on home built Fusion Drive
Authored by: herothedog on Nov 06, '12 09:25:16AM

diskutil shows that both drives have a recovery boot partition. So it seems if one drive fails, one would still be able to boot with the recovery partition.



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Mountain Lion installation on home built Fusion Drive
Authored by: BiL Castine on Nov 07, '12 07:21:12AM

Interesting finding. I was not able to clone a recovery partition to the Fusion drive using CarbonCopyCloner, but I didn't try installing the OS on a blank drive. Good to know Apple's installer already handles Fusion drives in an overly cautious manner. Now to see if i can create recovery partitions on the existing Fusion drive without having to reinstall the OS…



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Mountain Lion installation on home built Fusion Drive
Authored by: BiL Castine on Nov 06, '12 07:30:25AM
I followed Jinx's procedure using a Mac mini server and it was almost trivial to set up (as a bonus, i learned a bit about using the command line hdutil command). the hardest part for me was replacing one of the internal drives with an SSD. The mini is very tight and requires a specialized "logic board removal tool" (bent coat hanger) to slide out the logic board. Luckily iFixit has full instructions and a tool set. Since my OS was installed on only one of the two internal HDDs i was able to extract that drive, replace it with the SSD, place the drive with the OS in an external drive dock, boot from the OS drive, create the CoreStorage volume, then clone the OS to the Fusion drive. Upon booting from the new Fusion drive, i noticed an immediate speed improvement, though i should admit the server OS was small enough to entirely fit on the 256GB SSD.

Of note: you'll want to keep a full backup, as it is not currently possible to create a recovery partition on a CoreStorage volume. I'm using CarbonCopyCloner to create a disk image on a network share once a week, and CrashPlan to backup frequently changing files to another computer in my home (CrashPlan is free when used this way).

Once I'm convinced this is a stable configuration, I'll be repeating it with my 2011 MacBook Pro (256GB SSD, 1TB HDD, OWC DataDoubler) where i really expect to see a speed boost. My home folder and library wouldn't fit on the SSD so once the machine boots, it slows down again as programs access the user library folder. CoreStorage should really shine in this setting.

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Mountain Lion installation on home built Fusion Drive
Authored by: artificemm on Nov 07, '12 04:52:41PM

No issues so far with a MBP8,1 with stock 500GB drive + OWC Mercury 6G 128GB, CoreStorage process was smooth, MBP feels exactly the same. It saved me from struggling with moving the user from the startup drive in order to save space on the SSD.



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Mountain Lion installation on home built Fusion Drive
Authored by: tiptongrange on Nov 07, '12 10:34:35PM

I did this on a 2010 MacBook Pro that has a 340GB hard drive and a 120GB SSD. However, in the last command of Part 1 that begins with: diskutil cs createVolume..., I used 100% as the last argument instead of 500g. This ensures that the entire drives are used. I then did a fresh install of Mountain Lion, but this method won't create a recovery partition. The command 'diskutil list' gives this:


gbh-mbp-3:~ gbh$ diskutil list
/dev/disk0
#: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme *120.0 GB disk0
1: EFI 209.7 MB disk0s1
2: Apple_CoreStorage 119.7 GB disk0s2
3: Apple_Boot Boot OS X 134.2 MB disk0s3
/dev/disk1
#: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme *320.1 GB disk1
1: EFI 209.7 MB disk1s1
2: Apple_CoreStorage 319.2 GB disk1s2
3: Apple_Boot Boot OS X 650.0 MB disk1s3
/dev/disk2
#: TYPE NAME SIZE IDENTIFIER
0: Apple_HFS MBP FusionDrive *436.5 GB disk2


The partitions named 'Apple_Boot Boot OS X' don't show under System Preferences > Startup Disk, but FusionDrive does show. However, if I hold the Option key when booting, two hard disk icons labeled FusionDrive show as an option to boot from. When I select each, they both boot from the SSD. So, I'm guessing that the two icons represent the two Apple_Boot Boot OS X partitions, and that they are linked to the logical volume startup, which is located on the SSD--even if the partition on the HDD is selected.



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Mountain Lion installation on home built Fusion Drive
Authored by: finnp on Nov 17, '12 01:13:20PM

Same here, two hard disks with same name when booting with option key. I used 100% as you and installed from an USB stick.
The drive seem to function OK,-but not as blazing fast as I've seen in other tests. After MT install I used migration assistant to get my old account from a Superduper clone, no problems there.
Imac late 2009 2GB HD, samsung 830 256GB in optical bay



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