Date: Sat, 27 Sep 1997 11:59:09 +0200 (IST) From: Nadav Eiron <nadav@barcode.co.il> To: Alec Kloss <alec@d2si.com> Cc: freebsd-questions@FreeBSD.ORG Subject: Re: Adaptec 3940UW performance with two drives Message-ID: <Pine.BSF.3.91.970927115728.14874C@gatekeeper.barcode.co.il> In-Reply-To: <199709262104.QAA02443@d2si.com>
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On Fri, 26 Sep 1997, Alec Kloss wrote: > Howdy. I have an Adaptec 3940UW controller in a machine. The 3940UW > has two SCSI busses on it. Originally, I had two Quantum XP34550W > drives on bus A and a Jaz drive and a CDROM drive on bus B. I got > sick of the Jaz drive and CDROM (I never used them anyway) so I > removed them. Is there any reason to (or not to) move one of the > Quantum's onto bus B? I suspect it is important to observe that I do > not copy data between the two drives very often. > > No. There is actually a gain in performance by splitting your I/O between the busses. If the transfers are between devices on different busses the read and write operations do not contend for bandwidth on the SCSI bus. However, I doubt it that your two disks saturate even a single bus under normal operation, so you'll probably see only small changes in performance anyhow. Nadav
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