Offline uncorrectable sectors in SSDs being used for ZFS L2ARC?

user260467 asked:

I have two enterprise-grade SSDs that I’ve been using for L2ARC in an OpenZFS pool for a few years. Workflow during this time has been fairly heavy, with lots of reads and writes, serving up video to clients for video post-production.

Recently, got a couple of critical alerts about the L2ARC SSDs:

CRITICAL: Oct. 22, 2018, 6:12 p.m. - Device: /dev/da0 [SAT], 215869351264256 Offline uncorrectable sectors
CRITICAL: Oct. 22, 2018, 6:12 p.m. - Device: /dev/da1 [SAT], 174264003067904 Offline uncorrectable sectors

Obviously there’s no risk of data loss, since these are just L2ARC, but is it time to just get them replaced?

Am I sacrificing performance? If not, is there a way to reset or ignore the bad sectors?

Using FreeNAS-11.1-U6.

My answer:


Those numbers are obviously bogus. Your SSD doesn’t have that many sectors at all, let alone offline uncorrectable ones. Check for firmware updates for your SSD that will fix the problem. Otherwise, ignore it. If you’re really paranoid, you could replace the drives, but in that case you should use different drives, not the same brand from the same manufacturer (because they obviously have faulty firmware).


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