Andrey Kuzmin wrote:
On Wed, Dec 16, 2009 at 7:25 PM, Kjetil Torgrim Homme
<kjeti...@linpro.no> wrote:
Andrey Kuzmin <andrey.v.kuz...@gmail.com> writes:
Yet again, I don't see how RAID-Z reconstruction is related to the
subject discussed (what data should be sha256'ed when both dedupe and
compression are enabled, raw or compressed ). sha256 has nothing to do
with bad block detection (may be it will when encryption is
implemented, but for now sha256 is used for duplicate candidates
look-up only).
how do you think RAID-Z resilvering works? please correct me where I'm
wrong.
Resilvering has noting to do with sha256: one could resilver long
before dedupe was introduced in zfs.
SHA256 isn't just used for dedup it is available as one of the checksum
algorithms right back to pool version 1 that integrated in build 27.
SHA256 is also used to checksum the pool uberblock.
This means that SHA256 is used during resilvering and especially so if
you have checksum=sha256 for your datasets.
If you still don't believe me check the source code history:
http://src.opensolaris.org/source/history/onnv/onnv-gate/usr/src/uts/common/fs/zfs/zio_checksum.c
http://src.opensolaris.org/source/history/onnv/onnv-gate/usr/src/uts/common/fs/zfs/sha256.c
Look at the date when that integrated 31st October 2005.
In case you still doubt me look at the fix I just integrated today:
http://mail.opensolaris.org/pipermail/onnv-notify/2009-December/011090.html
--
Darren J Moffat
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