A corrupt Fusion Drive
It was yesterday early evening when my MacBook Pro decided to give me lots of error messages regarding corrupt or missing files in increasing frequency. All these messages indicated a problem with my hard drive: my manually created Fusion Drive consisting of a 256GB SSD and a 500GB HDD.
Disk Utility confirmed that the drive needed repair, but told me I have to repair it when booting from the Recovery Partition. But trying to repair it from there was not successful, either. And from then on the machine refused to boot. It crashed/turned off, right after I entered my password – which I had to enter early, because my drive was encrypted with FileVault.
I have been a bit suspicious of my Fusion Drive in the past 1.5 years, because most times when I checked with Disk Utility, it was in need of repair. This could be repaired most of the time, but I was still not feeling too good about it.
And then I found out after the crash yesterday, that the original author of the “How to build your own Fusion Drive”-tutorial does not use a Fusion Drive on HFS+-formatted hard drives, because he found it’s not keeping his data safe:
Btw.: I will actually not use Fusion drive on a Mac as HFS+ is not really keeping my data safe (see my HFS+ fails miserably demo). Using two HFS+ disks concatenated just increases the risk of data failure. And TimeMachine as backup has failed me as well in the past.
So, I decided to split up the Fusion drive, re-installed Yosemite on the SSD, and copied over my data from the Time Machine backup via Migration Assistant.
Now I keep the OS, apps, code and as much of the other data as possible on the SSD, and store my large media files (photos, music, videos) on the old, spinning, still-internal HDD.
I don’t know what the underlying problem was really, but I’m not keen to risk my data to a buggy Fusion Drive any longer. My system is now back up and running again and Disk Utility tells me that both my SSD and my HDD “appear to be OK”.