Date: Tue, 8 Feb 2005 23:03:28 -0600 From: Dan Nelson <dnelson@allantgroup.com> To: "Marc G. Fournier" <scrappy@hub.org> Cc: freebsd-questions@freebsd.org Subject: Re: vinum in 4.x poor performer? Message-ID: <20050209050328.GA78932@dan.emsphone.com> In-Reply-To: <20050209002232.B94338@ganymede.hub.org> References: <20050208231208.B94338@ganymede.hub.org> <20050209034624.GN28715@wantadilla.lemis.com> <20050209002232.B94338@ganymede.hub.org>
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In the last episode (Feb 09), Marc G. Fournier said: > On Wed, 9 Feb 2005, Greg 'groggy' Lehey wrote: > >On Tuesday, 8 February 2005 at 23:21:54 -0400, Marc G. Fournier wrote: > >>I have a Dual-Xeon server with 4G of RAM, with its primary file > >>system consisting of 4x73G SCSI drives running RAID5 using vinum > >>... the operating system is currently FreeBSD 4.10-STABLE #1: Fri > >>Oct 22 15:06:55 ADT 2004 ... swap usage is 0% (6149) ... and it > >>performs worse then any of my other servers, and I have less > >>running on it then the other servers ... > >> > >>I also have HTT disabled on this server ... and softupdates enabled > >>on the file system ... > >> > >>That said ... am I hitting limits of software raid or is there > >>something I should be looking at as far as performance is > >>concerned? Maybe something I have misconfigured? > > > >Based on what you've said, it's impossible to tell. Details would > >be handy. > > Like? I'm not sure what would be useful for this one ... I just sent > in my current drive config ... something else useful? Details on the array's performance, I think. Software RAID5 will definitely have poor write performance (logging disks solve that problem but vinum doesn't do that), but should have excellent read rates. From this output, however: > systat -v output help: > 4 users Load 4.64 5.58 5.77 > Proc:r p d s w Csw Trp Sys Int Sof Flt > 24 9282 949 8414***** 678 349 8198 > 54.6%Sys 0.2%Intr 45.2%User 0.0%Nice 0.0%Idl > Disks da0 da1 da2 da3 da4 pass0 pass1 > KB/t 5.32 9.50 12.52 16.00 9.00 0.00 0.00 > tps 23 2 4 3 1 0 0 > MB/s 0.12 0.01 0.05 0.04 0.01 0.00 0.00 > % busy 3 1 1 1 0 0 0 , it looks like your disks aren't being touched at all. You are doing over 99999 syscalls/second, though, which is mighty high. The 50% Sys doesn't look good either. You may have a runaway process doing some syscall over and over. If this is not an MPSAFE syscall (see /sys/kern/syscalls.master ), it will also prevent other processes from making non-MPSAFE syscalls, and in 4.x that's most of them. -- Dan Nelson dnelson@allantgroup.com
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