Date: Mon, 28 Jan 2013 12:00:55 +0000 From: Laurence Gill <laurencesgill@googlemail.com> To: Pawel Jakub Dawidek <pjd@FreeBSD.org> Cc: freebsd-fs@freebsd.org Subject: Re: HAST performance overheads? Message-ID: <20130128120055.6ca7c734@googlemail.com> In-Reply-To: <20130127134845.GC1346@garage.freebsd.pl> References: <20130125121044.1afac72e@googlemail.com> <20130127134845.GC1346@garage.freebsd.pl>
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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On Sun, 27 Jan 2013 14:48:46 +0100 Pawel Jakub Dawidek <pjd@FreeBSD.org> wrote: > On Fri, Jan 25, 2013 at 12:10:44PM +0000, Laurence Gill wrote: > > If I create ZFS raidz2 on these... > > > > - # zpool create pool raidz2 da0 da1 da2 da3 da4 da5 > > > > Then run a dd test, a sample output is... > > > > - # dd if=/dev/zero of=test.dat bs=1M count=1024 > > 1073741824 bytes transferred in 7.689634 secs (139634974 > > bytes/sec) > > > > - # dd if=/dev/zero of=test.dat bs=16k count=65535 > > 1073725440 bytes transferred in 1.909157 secs (562408130 > > bytes/sec) > > > > This is much faster than compared to running hast, I would expect an > > overhead, but not this much. For example: > > > > - # hastctl create disk0/disk1/disk2/disk3/disk4/disk5 > > - # hastctl role primary all > > - # zpool create pool raidz2 disk0 disk1 disk2 disk3 disk4 disk5 > > > > Run a dd test, and the speed is... > > > > - # dd if=/dev/zero of=test.dat bs=1M count=1024 > > 1073741824 bytes transferred in 40.908153 secs (26247624 > > bytes/sec) > > > > - # dd if=/dev/zero of=test.dat bs=16k count=65535 > > 1073725440 bytes transferred in 42.017997 secs (25553942 > > bytes/sec) > > Let's try to test one step at a time. Can you try to compare > sequential performance of regular disk vs. HAST with no secondary > configured? > > By no secondary configured I mean 'remote' set to 'none'. > > Just do: > > # dd if=/dev/zero of=/dev/da0 bs=1m count=10240 > > then configure HAST and: > > # dd if=/dev/zero of=/dev/hast/disk0 bs=1m count=10240 > > Which FreeBSD version is it? > > PS. Your ZFS tests are pretty meaningless, because it is possible that > everything will end up in memory. I'm sure this is what happens in > 'bs=16k count=65535' case. Let try raw providers first. > Thanks for the reply. I'm using FreeBSD 9.1-RELEASE. Here are the results: # dd if=/dev/zero of=/dev/da0 bs=1m count=10240 10737418240 bytes transferred in 755.144644 secs (14219022 bytes/sec) # dd if=/dev/zero of=/dev/hast/disk0 bs=1m count=10240 10737418240 bytes transferred in 844.167602 secs (12719534 bytes/sec) Which indicates a very small overhead, hmmm... - -- Laurence Gill f: 08721 157 665 skype: laurencegg e: laurencesgill@googlemail.com PGP on Key Servers -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.19 (GNU/Linux) iEYEARECAAYFAlEGaH4ACgkQygVt8Sq0Pf8QaQCfX4/SAGnwYXfCxJ+FFnE1OiRv R3MAn22bxjhXnCO5Aqsx74Gxq5ZemUjX =7dgR -----END PGP SIGNATURE-----
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