Is my Fusion Drive OK (2.2 TB and 801.44 GB partitions)?

vladobizik

macrumors 6502
Original poster
Aug 21, 2012
321
86
Slovakia
I have a 3TB Fusion Drive and when I look at it in Disk Utility it shows as split between two partitions - one is 2,2 TB, the other 801,44 GB. There is also 127 KB of unused space. I used to have a Boot Camp partition, but I have now removed it (using Boot Camp Assistant).

Everything works fine I think, Finder sees the drive as a singular 3,11 TB drive. I'd just like to ask if there's really nothing wrong with how my Fusion Drive is partitioned and if this is the way it workd for everybody. Thanks.
 

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Samuelsan2001

macrumors 604
Oct 24, 2013
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2,118
I have a 3TB Fusion Drive and when I look at it in Disk Utility it shows as split between two partitions - one is 2,2 TB, the other 801,44 GB. There is also 127 KB of unused space. I used to have a Boot Camp partition, but I have now removed it (using Boot Camp Assistant).

Everything works fine I think, Finder sees the drive as a singular 3,11 TB drive. I'd just like to ask if there's really nothing wrong with how my Fusion Drive is partitioned and if this is the way it workd for everybody. Thanks.
Have you tried rebooting it??

That will sometimes reset this.
 

vkd

macrumors 6502a
Sep 10, 2012
908
310
From the screenshot you provided, it looks to me like you have the original, Fusion Drive 'Macintosh HD' which is highlighted, and a second 'Macintosh HD' below it, not highlighted, which presumably was formerly your Boot Camp drive. I imagine you deleted your Boot Camp drive and created a new partition in its place and named it 'Macintosh HD', in the hope that it would merge with your existing 'Macintosh HD'. If you did (think like that), then sorry to say, it didn't merge, it's a bit more complex than that. AFAIK you cannot easily add in and change the size of a Fusion Drive once its been created. Try renaming that second 'Macintosh HD' to something else whilst you are in Disk Utility, then have a look in Finder and see if it appears there.
 

vladobizik

macrumors 6502
Original poster
Aug 21, 2012
321
86
Slovakia
From the screenshot you provided, it looks to me like you have the original, Fusion Drive 'Macintosh HD' which is highlighted, and a second 'Macintosh HD' below it, not highlighted, which presumably was formerly your Boot Camp drive. I imagine you deleted your Boot Camp drive and created a new partition in its place and named it 'Macintosh HD', in the hope that it would merge with your existing 'Macintosh HD'. If you did (think like that), then sorry to say, it didn't merge, it's a bit more complex than that. AFAIK you cannot easily add in and change the size of a Fusion Drive once its been created. Try renaming that second 'Macintosh HD' to something else whilst you are in Disk Utility, then have a look in Finder and see if it appears there.

Thanks for your reply. I did not delete the Boot Camp partition and rename it manually, all I did is remove the BC partition using Boot Camp Assistant. I may not have made it clear enough in my original post, so please know that in Finder, I see just one single Fusion Drive and it does have the proper size of over 3TB.

Googling the issue has taught me that originally 3TB Fusion Drives didn’t support Boot Camp at all because there is an inherent limit of sorts for Windows partitions of 2.2 TB. Later Apple came up with a solution that splits the drive behind-the-scenes, so that Windows is compatible with it. After I removed the Windows partition, I ended up with the drive still split up, though it’s still largely transparent. Judging from your reply, though, I think it’s not how it’s supposed to be.

I maintain a Time Machine backup on my Time Capsule, so what I think I’ll do is boot up the Yosemite installer from a USB stick and try to re-format the whole drive. I may resort to the solutions involving Terminal. Then I’ll just reload the whole system from the TM backup overnight.
 
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