On Thu, 1 Apr 2010, casper....@sun.com wrote:
It does seem like rollback to a snapshot does help here (to assure
that sync & async data is consistent), but it certainly does not help
any NFS clients. Only a broken application uses sync writes
sometimes, and async writes at other times.
But doesn't that snapshot possibly have the same issues?
No, at least not based on my understanding. My understanding is that
zfs uses uniform prioritization of updates and performs writes in
order (at least to the level of a TXG). If this is true, then each
normal TXG will be a coherent representation of the filesystem.
If the slog is used to recover uncommitted writes, then the TXG based
on that may not match the in-memory filesystem at the time of the
crash since async writes may have been lost.
Bob
--
Bob Friesenhahn
bfrie...@simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer, http://www.GraphicsMagick.org/
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