On 12/29/17 00:55, Andy Smith wrote: > The killer feature of ZFS is its checksumming of all data and > metadata to protect against bitrot and other forms of data > corruption. The only other filesystem offering this on Linux is > btrfs, hence the many mentions of ZFS in this thread. Putting the > filesystem under MD RAID (or hardware RAID) and scrubbing it will > detect corruption but cannot fix it. >
md-raid6 can fix most few-byte issues online. # dd if=/dev/zero of=/dev/sdb1 bs=1 count=1 seek=1234 md-raid6 scrub will fix that byte. Remember to always flush disc caches when testing! But unlike btrfs-raid10, md-raid6 cannot recover a whole disk or partition getting fully zero-dd'd - with or without a reboot. I didnt actually test how much of a disk must be zeroed or random'ed before md-raid6 scrub starts to fail. A few calls to the above dd with diffrent seek= and then scrubbing will fix the corrupted bytes every time. A full zero-dd will not. -> drive will be "failed" and you need to re-add it. Which was the reason why we initially gave btrfs-raid10 a try... ... it would be a really cool FS, if it was as stable as it is on my laptop (and I really dislike btrfs-raid definitions) You still can go md-raid + btrfs, if you want some btrfs features. Snapshots (and send/receive) are what I really love on my laptop and could not live without anymore. (fulldisk encryption may be mandatory, as btrfs at least some time ago, had the tendency to brick itself, if it sees its uuid on multiple disks at the same time (md-raid1)) br, Jan Vales -- I only read plaintext emails.
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