3 ms·

I don't have the answer, but it's an interesting question. Given that XFS doesn't do replication, like ZFS or BTRFS does, having integrity checks is a bit weird

I don't have the answer, but it's an interesting question. Given that XFS doesn't do replication, like ZFS or BTRFS does, having integrity checks is a bit weird. If a check fails, what is XFS suppose to do about it? If the filesystem can "recover" or deal with failed integrity checks, it makes sense to have them at that layer. If it can't, I'd say that the application, in this case a database, should do it's own integrity checks. If it's just a few rows or tables, the operator can easily recover those from a backup. Having the filesystem, which knows nothing about the data, report the failure will mean having to do a full restore from backups.

tmikaeld 4y ago
ZFS RAIDZ can reconstruct damaged data, thanks to the extra checksum provided by ZFS. While traditional RAID does not recover from silent data corruption because it does not know which block to reconstruct. This is exceptionally sensitive when backups are encrypted, because even a few bits off and you can't decrypt the backups. Since this happens transparently, regularly testing backups are very important in non-ZFS systems.
- dijit 4y ago
  ZFS is more akin to a logical volume manager (inc. software raid) and a filesystem though. XFS is just a filesystem, it's not trying to solve the same issues. Higher end RAID cards also do block level validations in the background. It isn't filesystem aware but it is sufficient to suss out bad clusters and relocate data proactively. The point of ZFS systems is to avoid such hardware based checksumming systems, but RAID cards have been doing this validation for many years now. The hardware solutions we have now provide silent corruption protection from the storage controller down to the actual media. ZFS extends that protection to the filesystem layer in the kernel and when used in isolation of modern hardware solutions can protect the whole stack.

tmikaeld 4y ago

ZFS RAIDZ can reconstruct damaged data, thanks to the extra checksum provided by ZFS. While traditional RAID does not recover from silent data corruption because it does not know which block to reconstruct. This is exceptionally sensitive when backups are encrypted, because even a few bits off and you can't decrypt the backups. Since this happens transparently, regularly testing backups are very important in non-ZFS systems.

dijit 4y ago
ZFS is more akin to a logical volume manager (inc. software raid) and a filesystem though. XFS is just a filesystem, it's not trying to solve the same issues. Higher end RAID cards also do block level validations in the background. It isn't filesystem aware but it is sufficient to suss out bad clusters and relocate data proactively. The point of ZFS systems is to avoid such hardware based checksumming systems, but RAID cards have been doing this validation for many years now. The hardware solutions we have now provide silent corruption protection from the storage controller down to the actual media. ZFS extends that protection to the filesystem layer in the kernel and when used in isolation of modern hardware solutions can protect the whole stack.