Hacker News Reader

Comment by z3t4 | Hacker News Reader

There is however no point in having data checks if there are no way of recovering, so running ZFS only make sense if you have multiple disks. And don't forget to scrub your pool!

View on HN

This is like saying "there's no point in ECC if it can't correct every error" ... which simply isn't true. It's still far better to know that corruption exists -- so you can know something is invalid and potentially take action -- than to have corruption silently hanging around doing corrupted data things.

That is not a fair comparison as ECC is Error Correcting, while just check-summing is not. If you however have a mirror or raid-Z the file system will be able to correct.

Knowing that your data is corrupt is always better than not knowing.

Whether or not you have a RAID you should still have backups, and you don't want to replace a good backup by a corrupt one.

OK, so you know your HDD is corrupted, and you now have to take the site down to recover from backup, which is also old, so there will be data missing. Compared to if the FS can just fix itself. Sometimes not knowing can be a bliss though. :P

You can set the number of copies to keep at filesystem level. This is in addition to any redundancy provided at pool level (if any). It won't save you from a failed disk, but it will be able to transparently correct any checksum error.

There definitely is a point. ZFS can tell you which files are corrupted and you can restore them from a backup.

Reply on news.ycombinator.com