Date: Wed, 24 Feb 1999 15:09:30 +0200 From: Ruslan Ermilov <ru@ucb.crimea.ua> To: "Kenneth D. Merry" <ken@plutotech.com>, allenc@verinet.com, gallatin@cs.duke.edu Cc: hardware@freebsd.org Subject: Tagged queueing and write cache on WDE SCSI drives Message-ID: <19990224150930.A6284@ucb.crimea.ua> In-Reply-To: <199902240617.XAA37750@panzer.plutotech.com>; from Kenneth D. Merry on Tue, Feb 23, 1999 at 11:17:59PM -0700 References: <19990223182845.A32766@ucb.crimea.ua> <199902240617.XAA37750@panzer.plutotech.com>
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Hi! I have tested all four combinations for Tagged Queueing (TQ) and Write Cache option (WC). The following hardware was used: ahc0: <Adaptec aic7880 Ultra SCSI adapter> rev 0x00 da0: <WDIGTL ENTERPRISE 1.80> Fixed Direct Access SCSI-2 device The following tests were run (5 times for each combination) in single user mode: dd if=/dev/zero of=test bs=64k count=1000 Here's my results (in MB/s): WC TQ MB/s ======= ======= ==== OFF OFF 3.9 OFF ON 4.2 ON OFF 7.9 ON ON 4.2 The best performance is achieved with WC=ON and TQ=OFF. Comments? More tests? Is this WD-specific? What are the pros and cons of enabling write cache? P.S. `bonnie' gives nearly the same results. Cheers, -- Ruslan Ermilov Sysadmin and DBA of the ru@ucb.crimea.ua United Commercial Bank +380.652.247.647 Simferopol, Ukraine http://www.FreeBSD.org The Power To Serve http://www.oracle.com Enabling The Information Age To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hardware" in the body of the message
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