svn commit: r243524 - in head: cddl/contrib/opensolaris/cmd/ztest sys/cddl/contrib/opensolaris/uts/common/fs/zfs sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys

[Pawel Jakub Dawidek]

On Sun, Nov 25, 2012 at 04:32:08PM +0000, Martin Matuska wrote:
> Author: mm
> Date: Sun Nov 25 16:32:07 2012
> New Revision: 243524
> URL: http://svnweb.freebsd.org/changeset/base/243524
> 
> Log:
>   MFV r243013 and r243267:
>   
>   Import the zio nop-write improvement from Illumos. To reduce I/O,
>   nop-write omits overwriting data if the checksum (cryptographically
>   secure) of new data matches the checksum of existing data.
>   It also saves space if snapshots are in use.
>   
>   It currently works only on datasets with enabled compression, disabled
>   deduplication and sha256 checksums.
>   
>   IllumOS 13887:196932ec9e6a and 13888:7204b3392a58
>   3236 zio nop-write

This is a nice change, although I don't understand why it depends on
compression being turned on. It won't save any space.

-- 
Pawel Jakub Dawidek                       http://www.wheelsystems.com
FreeBSD committer                         http://www.FreeBSD.org
Am I Evil? Yes, I Am!                     http://tupytaj.pl
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