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
Ronald Klop
ronald-freebsd8 at klop.yi.org
Mon Nov 26 10:27:41 UTC 2012
On Sun, 25 Nov 2012 17:39:24 +0100, Pawel Jakub Dawidek <pjd at freebsd.org>
wrote:
> 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.
>
This question is also discussed here.
http://comments.gmane.org/gmane.os.illumos.zfs/200
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