COW for Flash?
Posted Jun 18, 2007 17:26 UTC (Mon) by qu1j0t3
In reply to: good to hear
Parent article: Linus on GPLv3 and ZFS
It has been said that COW is ideal for Flash. Can you explain why ZFS isn't relevant here?
There is no fsck; ZFS is "always consistent on disk" (through COW+atomic transactions). It seems to me this is a necessary invariant to achieve its other features (such as snapshots). Debate flares up (occasionally) as to whether a scavenger will be necessary. If so, it won't much resemble 'fsck' - and certainly won't be run in normal operation or after reset/powerfail/etc (ZFS behaviour under impromptu reset is extremely well tested).
I suspect, but correct me if I'm wrong, once you "know" you've lost data in ZFS (through exhausting redundancy or ditto blocks), it's actually gone by definition, and unrecoverable by re-creating links. No doubt Bonwick et all have explained it better somewhere...
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