Date: Sat, 30 Jul 2005 12:33:55 +0200 From: "Poul-Henning Kamp" <phk@phk.freebsd.dk> To: Julian Elischer <julian@elischer.org> Cc: FreeBSD Current <freebsd-current@freebsd.org> Subject: Re: Apparent strange disk behaviour in 6.0 Message-ID: <98853.1122719635@phk.freebsd.dk> In-Reply-To: Your message of "Sat, 30 Jul 2005 03:29:27 PDT." <42EB5687.2070400@elischer.org>
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In message <42EB5687.2070400@elischer.org>, Julian Elischer writes: >Poul-Henning Kamp wrote: >> In message <42E88135.30603@elischer.org>, Julian Elischer writes: >> >> Please use gstat and look at the service times instead of the >> busy percentage. > >The snapshot below is typical when doing tar from one drive to another.. >(tar c -C /disk1 f- .|tar x -C /disk2 -f - ) > >dT: 1.052 flag_I 1000000us sizeof 240 i -1 > L(q) ops/s r/s kBps ms/r w/s kBps ms/w d/s kBps ms/d %busy Name > 0 405 405 1057 0.2 0 0 0.0 0 0 0.0 9.8 | ad0 > 0 405 405 1057 0.3 0 0 0.0 0 0 0.0 11.0 | ad0s2 > 0 866 3 46 0.4 863 8459 0.7 0 0 0.0 63.8 | da0 > 25 866 3 46 0.5 863 8459 0.8 0 0 0.0 66.1 | da0s1 > 0 405 405 1057 0.3 0 0 0.0 0 0 0.0 12.1 | ad0s2f > 195 866 3 46 0.5 863 8459 0.8 0 0 0.0 68.1 | da0s1d > >even though the process should be disk limitted neither of the disks is anywhere >near 100%. This looks like an awful lot of small files since you write 8 times as much data as you read ? Since the write service time (ms/w) is low, I pressume you have some hefty disk hardware (with cache ?) Presumably you're using softupdates ? I wouldn't be surprised if you were limited by system time rather than disk in this scenario ? -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 phk@FreeBSD.ORG | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence.
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