Date: Sun, 22 Dec 2013 10:58:41 +0000 (UTC) From: Craig Rodrigues <rodrigc@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r259715 - head/release/doc/en_US.ISO8859-1/relnotes Message-ID: <201312221058.rBMAwflK007175@svn.freebsd.org>
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Author: rodrigc Date: Sun Dec 22 10:58:40 2013 New Revision: 259715 URL: http://svnweb.freebsd.org/changeset/base/259715 Log: Mention ZFS zio nop-write improvement. Modified: head/release/doc/en_US.ISO8859-1/relnotes/article.xml Modified: head/release/doc/en_US.ISO8859-1/relnotes/article.xml ============================================================================== --- head/release/doc/en_US.ISO8859-1/relnotes/article.xml Sun Dec 22 10:52:51 2013 (r259714) +++ head/release/doc/en_US.ISO8859-1/relnotes/article.xml Sun Dec 22 10:58:40 2013 (r259715) @@ -342,6 +342,14 @@ <para revision="252140">Support for L2ARC compression has been added to ZFS.</para> + <para revision="243524">The zio nop-write improvement from Illumos + was imported into &os;. To reduce I/O, nop-write skips 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. This improvement only works only on + datasets with enabled compression, disabled deduplication and + sha256 checksums.</para> + <para>ZFS will now compare the checksums of incoming writes to the checksum of the existing on-disk data and avoid issuing any write I/O for data that has not changed. This will reduce I/O
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