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macrumors newbie
Original poster
Dec 31, 2015
I ordered a 1Tb SSD to be installed in my iMac 27 mid 2011 wurrently ith a 1Tb HDD.

Should i make a fusion drive or two seperate?
If seperate drives, then install OS X on SSD and what I use most?
Any experience of lost data on fusion drive - I read this can happen due to no check of data transfer between the two disks.

Any issues I don't list here?



macrumors 6502a
Feb 28, 2012
Well, fusing the two drives would save you from having to manage your disk space yourself. I haven't heard of any problems with lost data on Fusion drives - well, that's only going by being a fairly regular visitor to this forum and I would have thought something would have come up here if anywhere. In any case, I can't imagine that Fusion would skip the standard disk write checks. The only caveat I have is that if you fuse the drives, they will be treated and fail as one. So, there is perhaps an increased chance of failure over a separate SSD, but we're still talking about reliable pieces of kit and since you will be taking regular backups anyway, I don't think that's necessarily much of an issue.


macrumors 601
Aug 28, 2012
Between the coasts
I've been using Fusion for several years without a problem.

It's an intriguing idea to fuse a 1 TB SSD with a 1 TB HDD. I'm not sure you'll see dramatic improvement over keeping the drives separated, but it would save you the trouble of deciding what is best to have stored on the SSD. I trust the OS to do that better than I could.

Most likely, nearly everything you access at the beginning is going to be bumped over to SSD by Fusion. After those initial "reads" at HDD speed, you'll likely be running at or close to full SSD speed until you substantially exceed 1 TB on the fused drives, and even then, most of what you do is likely to be pure SSD speed.

You'll no doubt start off by having the OS and commonly-used apps and data moved to the SSD. Chances are that it'll be a long time before anything is moved from SSD back to HDD due to disuse.

One concern I do have is that the old HDD is getting on in years, so it could be your Achilles heel. Fusion does not provide redundancy, so if/when that HDD fails, you'll need to restore the entire 2 TB "drive" to get back in business. Be sure you have a proper backup solution running.


macrumors newbie
Original poster
Dec 31, 2015
Tanks for the replies. I think I will give the fusion drive a chance, since the few disadvantages are of little risk and problem compared to the advantages. I miss the cable before I'm going to install the disk.
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