From owner-freebsd-scsi Sat May 4 14:30:27 1996 Return-Path: owner-freebsd-scsi Received: (from root@localhost) by freefall.freebsd.org (8.7.3/8.7.3) id OAA28357 for freebsd-scsi-outgoing; Sat, 4 May 1996 14:30:27 -0700 (PDT) Received: from hda.com (ip76-max1-fitch.zipnet.net [199.232.245.76]) by freefall.freebsd.org (8.7.3/8.7.3) with SMTP id OAA28347 for ; Sat, 4 May 1996 14:30:13 -0700 (PDT) Received: (from dufault@localhost) by hda.com (8.6.11/8.6.9) id RAA20783; Sat, 4 May 1996 17:33:19 -0400 From: Peter Dufault Message-Id: <199605042133.RAA20783@hda.com> Subject: Re: Buffered Writes? To: ec0@s1.GANet.NET (Eric Chet) Date: Sat, 4 May 1996 17:33:18 -0400 (EDT) Cc: asami@CS.Berkeley.EDU, dkelly@HiWAAY.net, freebsd-scsi@FreeBSD.ORG In-Reply-To: from "Eric Chet" at May 3, 96 03:28:29 pm Reply-to: hdalog@zipnet.net X-Mailer: ELM [version 2.4 PL24] Content-Type: text Sender: owner-freebsd-scsi@FreeBSD.ORG X-Loop: FreeBSD.org Precedence: bulk > > > Hello > Does anybody know how to or have a utility to turn on the > write cache on a barracuda? I have a wide barracuda on a NCR 825 and > would like to see if there is any performance difference. You would use the "-e" option of the mode page editor to edit mode page 8 and set the "WCE" (write cache enable) field to 1 to enable write back cacheing. Do "man 8 scsi". This will be similar to the async update of your file system meta data - you will introduce the problem of deferred errors, which presently will give you an error on the wrong disk transfer and treat the failed transfer as successful, and you'll have the possibility of not writing out the buffer on the disk in the case of power failure (unless your drive can write during spindown). -- Temporarily via "hdalog@zipnet.net"... Peter Dufault Real-Time Machine Control and Simulation HD Associates, Inc. Voice: 508 433 6936 dufault@hda.com Fax: 508 433 5267