Date: Thu, 19 Feb 2004 15:33:33 +0200 From: Dmitry Alyabyev <dimitry@al.org.ua> To: freebsd-fs@freebsd.org Cc: performance@FreeBSD.org Subject: Re: strange performance dip shown by iozone Message-ID: <200402191533.33495.dimitry@al.org.ua> In-Reply-To: <200402181729.06202@misha-mx.virtual-estates.net> References: <200402181729.06202@misha-mx.virtual-estates.net>
next in thread | previous in thread | raw e-mail | index | archive | help
On Thursday 19 February 2004 00:29, mi+mx@aldan.algebra.com wrote: > Hello! > > I'm trying to tune the amrd-based RAID5 and have made several iozone > runs on the array and -- for comparision -- on the single disk connected > to the Serial ATA controller directly. > > The RAID-based FS was newfs-ed with ``-b 65536'', as it is intended to > store very large files. The single-disk FS was newfs-ed with defaults. > > No softupdates were enabled on either, since those seem to degrade iozone > results slightly (iozone reads/writes a single file anyway). > > The filesystems displayed different performance (reads are better with > RAID, writes -- with the single disk), but both have shown a notable dip > in writing (and re-writing) speed when iozone used the record lengthes > of 128 and 256. Can someone explain that? Is that a known fact? How can > that be avoided? > > The machine is an amd64 running a fresh -current. The disks are 200Gb > SATAs. RAID5 consists of 6 of them. which stripe size of RAID5 did you use ? -- Dimitry
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?200402191533.33495.dimitry>