Hacker News new | ask | show | jobs
by csirac2 4311 days ago
ZFS & btrfs detect and fix silent corruption - where no errors are emitted from the hardware.

I think the pertinent question is: when the filesystem goes to read a 4K block, and one drive's copy of this block in the RAID-1 set is different to its counterpart 4K block on another disk, which one wins?
1 comments
maaku 4310 days ago
I didn't specify RAID-1. RAID-5 or RAID-6 can reconstruct the correct value in a silent fail.

Honest question: how often to drives silently fail? Drives contain per-sector checksums these days, explicitly to prevent this problem.

link
radiowave 4310 days ago
I don't know how often they fail, but I will say that the failures that I hope I never see again (or at least, I hope I never see again outside of a ZFS system) are not drive failures, but those involving intermittent disk controller or backplane faults. In comparison to the chaos I've seen this cause on NTFS systems, ZFS copes astonishingly well.
link