Date: Sun, 30 Mar 2003 18:10:07 +0200 From: des@ofug.org (Dag-Erling =?iso-8859-1?q?Sm=F8rgrav?=) To: Lukas Ertl <l.ertl@univie.ac.at> Cc: freebsd-stable@freebsd.org Subject: Re: vinum performance Message-ID: <xzp8yuwj0o0.fsf@flood.ping.uio.no> In-Reply-To: <20030330163238.X23911@leelou.in.tern> (Lukas Ertl's message of "Sun, 30 Mar 2003 16:38:15 %2B0200 (CEST)") References: <20030330125138.K23911@leelou.in.tern> <xzpk7ehhxaf.fsf@flood.ping.uio.no> <20030330081831.5c4e317e.fearow@attbi.com> <xzpbrzthqpy.fsf@flood.ping.uio.no> <20030330163238.X23911@leelou.in.tern>
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Lukas Ertl <l.ertl@univie.ac.at> writes: > I'm currently testing with prime stripe sizes, but it doesn't seem to > help. I additionally added "options AHC_ALLOW_MEMIO" to the kernel, and it > has raised write performance in the single-disk case (although I'm not > happy with that one either; I expected a disk on a U160 controller to pump > out more than ~65MB/s). Does the data sheet for your disk indicate that it can in fact write much faster than that? The speed at which data is actually written to the media is much lower than the bus speed - the bus speed *has* to be higher to accomodate multiple devices. For instance, the "internal formatted transfer rate" for a recent 73GB Seagate Cheetah varies between 38.4 and 63.9 MB/s (depending on how far out from the spindle you're writing). You won't see higher average transfer speeds than that unless the data you're writing fits entirely within the disk's on-board cache. DES --=20 Dag-Erling Sm=F8rgrav - des@ofug.org
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