Is it possible to recover data from the SSD portion of a Fusion Drive? My HDD does not start at all (both in iMac and external USB enclosure) and the SSD seems to work fine (accessible via Target Disk Mode). Any help is appreciated!
Got a tip for us?
Let us know
Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.
Fusion Drive Recovery - HDD failure
- Thread starter Tim0
- Start date
- Sort by reaction score
The way I heard it is that the fragmentation does not start until the SSD is filled up to a degree (or completely), but I have no way to prove it. Guess I have to try to find someone who can check the HDD power circuits first.
The way a Fusion Drive works is that the OS continually migrates whatever data you're using most actively to the SSD so it can be accessed very quickly at SSD speed. Everything else on the Fusion Drive is stored on the slow HDD portion. On paper it's a great compromise between fast but expensive SSDs and cheap but bulky HDDs. In real life, failure of either physical device destroys the whole thing, giving you two potential points of failure instead of one.
So that "fragmentation" (if you want to call it that) is integral to the way it works -- versus the old sense of the term in which files stored on a single HDD would get written to physically separate sectors of the platters when you run out of contiguous space.
I know this is what they advertise for Fusion drives, but my (limited) experience tells me otherwise. I haven't been using Fusion lately (this is my kids' computer), but when I did it seemed that it was mostly working at SSD speeds until it was filled to the SSD capacity, and the HDD was initially silent. After that I could hear the HDD working every now and then, so I guess that's when the data migration started. I might be wrong, of course. Still, even if it does work as advertised, I mostly need the files that were created recently and accessed actively. They are rather small, so there is a big chance they are entirely on SSD.
Fishrrman
macrumors Nehalem
OP wrote:
"Is it possible to recover data from the SSD portion of a Fusion Drive? My HDD does not start at all (both in iMac and external USB enclosure) and the SSD seems to work fine (accessible via Target Disk Mode)."
If ONE of the two drives that comprises a "fusion drive" has failed, it becomes all-but impossible to get the data off the remaining (working) drive. Maybe Apple can do it, but I doubt anyone else can.
Hope you have a backup, because -- if you don't -- you may as well kiss that data goodbye.
Having said that...
You didn't tell us WHICH MAC you have, which is important because it tells us the size of the internal SSD portion of the fusion drive.
IF it's a 128gb size SSD, I would suggest that you erase it, install a fresh copy of the OS, your apps, and a "stripped down" user folder.
It will then become a fast (but small-sized) boot drive.
Get an EXTERNAL USB3 drive (HDD or SSD) to serve as "supplemental storage".
And one other thing...
I would recommend either CarbonCopyCloner or SuperDuper to BACK UP the Mac from this day forward.
Either one can save your behind in a "disaster moment" -- like the one you just had.
"Is it possible to recover data from the SSD portion of a Fusion Drive? My HDD does not start at all (both in iMac and external USB enclosure) and the SSD seems to work fine (accessible via Target Disk Mode)."
If ONE of the two drives that comprises a "fusion drive" has failed, it becomes all-but impossible to get the data off the remaining (working) drive. Maybe Apple can do it, but I doubt anyone else can.
Hope you have a backup, because -- if you don't -- you may as well kiss that data goodbye.
Having said that...
You didn't tell us WHICH MAC you have, which is important because it tells us the size of the internal SSD portion of the fusion drive.
IF it's a 128gb size SSD, I would suggest that you erase it, install a fresh copy of the OS, your apps, and a "stripped down" user folder.
It will then become a fast (but small-sized) boot drive.
Get an EXTERNAL USB3 drive (HDD or SSD) to serve as "supplemental storage".
And one other thing...
I would recommend either CarbonCopyCloner or SuperDuper to BACK UP the Mac from this day forward.
Either one can save your behind in a "disaster moment" -- like the one you just had.
It's an iMac 2011 with 256Gb SSD added. I realize what needs to be done for the future setup, but for now I am still looking into ways of reviving the HDD (which may still be possible since it's looking like a power-up problem) or salvaging any data from the SSD. I will probably just switch to the SSD once I exhaust all options.