ZFS Mirrored SSD’s

D

dndlnx

Looking to further decrease power usage, noise, and footprint of my file server. My current setup is a simple pair of mirrored mechanical drives.

I thought about doing the same thing with SSD's. Would it be worth it though? Maybe they aren’t as likely to fail, but having that copy to refer to in case of an error would be a plus? What do you think?
 
SSDs are not much more reliable then spinning disks. Given how quiet, small and inexpensive they are, having a pair of them is a good idea. Personally, I don't do that, but I should (it's particularly embarrassing that I don't, since I professionally work in redundant storage).

Since you seem to use ZFS (the thread is marked this way), this is super-easy to do, and can be done without reformatting your system: Just add two SSDs to the ZFS pool in question, wait for the re-silvering to finish (now you have 4 copies of the data, two on spinning, two on SSD), then remove the two mechanical drives. This will probably take a day or two, but requires very little work.
 
On my 2013 office server I have installed a pair of 128GB OCZ-VERTEX4 SSD in mirror for the FreeBSD OS and now, they have more than 45000 power on hours without any issue. This server has 3 mechanical drives in raidz1, but I have already replaced 3 disks from 2013! From my experience a SSD is more reliable than a spinning disk.
 
Yes, SSDs are more reliable than spinning disks, but they are not astronomically better, and they are not perfect. The common failure mode of SSDs is that the flash chips get worn out by overwriting the too often; the good news is when that happens, the drives are still readable, just not writeable, which means one can migrate the data to other drives. But that is not the only failure mode. I've seen quite a few drives that simply completely die with electronics failures. Another failure mode is corruption of the internal metadata, which leads to being able to read parts of the data only.

But they are still more reliable than spinning disks.
 
emmex said:
they have more than 45000 power on hours without any issue.
Click to expand...
Code: 
Model Family:     SandForce Driven SSDs
Device Model:     KINGSTON SV300S37A60G
{....}
  9 Power_On_Hours_and_Msec 0x0032   052   052   000    Old_age   Always       -       42184h+32m+13.790s
:D
 
Made me look! My two SSDs strangely have very different power-on hours: 43969 and 25576. Recently I've been using them in tandem, but I think the "backup" one was actually unplugged most of the time for a few years (it was only updated every few weeks, and never read). So old SSDs do exist. My spinning disks are relatively young by comparison (17505 and 39926 hours), because I had a whole set of Seagate drives die a few years ago (the surviving ones are all Hitachi).

For calibration: 1 years = 8766 hours; 5 years is about 44K hours (and usually assumed to be the economically useful lifetime of computer gear).
 
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