4 ms·

Most definitely yes. But in addition to this, standard Raid5 does not periodically read the data, so it's actually rather common for issues to only arise on a

Most definitely yes. But in addition to this, standard Raid5 does not periodically read the data, so it's actually rather common for issues to only arise on a resilver. This is why proper maintenance in ZFS is to run ZFS Scrub (basically check every file) once a week.

mmt 8y ago
That's also proper RAID5/6 maintenance. My main/recent familiarity is with LSI hardware RAID implementation, where they call it a "patrol read". I believe mdraid has checkarray. I'm not sure if you meant to imply that ZFS is different from standard RAID in this regard, but it doesn't seem as though it is.
- jacquesm 8y ago
  It's called scrubbing.
  - mmt 8y ago
    Did you mean to reply to my above question? If so, I'm unclear as to what you're trying to get across. Is ZFS scrubbing different than the other RAIDs' (scheduled or schedulable) reads of the entire array, other than nomenclature?
Siecje 8y ago
We use ZFS, how can I check if we are doing a ZFS Scrub every week?
- simcop2387 8y ago
  'zpool status' will tell you the last time a scrub was run, or if one is running currently and information about it. Then check your crons and see that they make sense and match what you see with zpool status.
  - Siecje 8y ago
    Well it is not every week. > scan: scrub repaired 0 in 0h36m with 0 errors on Sun Aug 12 06:00:50 2018 I don't see any cron jobs though...
    - simcop2387 8y ago
      Given the speed of that, I'd bet you don't have a huge pool (or if you do, that's a really nice speed). I'd bet someone's doing it manually. That's what I do for my own systems (about once a month) since they're not heavy use (personal and parent's file servers).
agapon 8y ago
Once a week sounds extreme unless we talk about a smallish SSD-only pool. You may wear out your (spinning) disks with scrubs more than you do with real workloads. Also, depending on a pool size it may take days for a scrub to complete.
- mmt 8y ago
  > You may wear out your (spinning) disks with scrubs more than you do with real workloads. This seems like an extraordinary claim requiring extraordinary evidence, especially since the notion of wear out is only applicable to SSDs (as shorthand for write endurance). I certainly believe that mechanical disks, with all those moving parts, can have their failure rates increased by increased use, but it's not safe to assume even something as high as a linearly proportional relationship, considering which parts move when.

mmt 8y ago

That's also proper RAID5/6 maintenance. My main/recent familiarity is with LSI hardware RAID implementation, where they call it a "patrol read". I believe mdraid has checkarray. I'm not sure if you meant to imply that ZFS is different from standard RAID in this regard, but it doesn't seem as though it is.

jacquesm 8y ago
It's called scrubbing.
- mmt 8y ago
  Did you mean to reply to my above question? If so, I'm unclear as to what you're trying to get across. Is ZFS scrubbing different than the other RAIDs' (scheduled or schedulable) reads of the entire array, other than nomenclature?

Siecje 8y ago

We use ZFS, how can I check if we are doing a ZFS Scrub every week?

simcop2387 8y ago
'zpool status' will tell you the last time a scrub was run, or if one is running currently and information about it. Then check your crons and see that they make sense and match what you see with zpool status.
- Siecje 8y ago
  Well it is not every week. > scan: scrub repaired 0 in 0h36m with 0 errors on Sun Aug 12 06:00:50 2018 I don't see any cron jobs though...
  - simcop2387 8y ago
    Given the speed of that, I'd bet you don't have a huge pool (or if you do, that's a really nice speed). I'd bet someone's doing it manually. That's what I do for my own systems (about once a month) since they're not heavy use (personal and parent's file servers).

agapon 8y ago

Once a week sounds extreme unless we talk about a smallish SSD-only pool. You may wear out your (spinning) disks with scrubs more than you do with real workloads. Also, depending on a pool size it may take days for a scrub to complete.

mmt 8y ago
> You may wear out your (spinning) disks with scrubs more than you do with real workloads. This seems like an extraordinary claim requiring extraordinary evidence, especially since the notion of wear out is only applicable to SSDs (as shorthand for write endurance). I certainly believe that mechanical disks, with all those moving parts, can have their failure rates increased by increased use, but it's not safe to assume even something as high as a linearly proportional relationship, considering which parts move when.