Date: Wed, 14 Mar 2001 23:53:20 +1300 From: Mark Ibell <marki@paradise.net.nz> To: Alfred Perlstein <bright@wintelcom.net> Cc: Mars Attack <marsattack@cannoncreek.com>, Soren Schmidt <sos@freebsd.dk>, Peter Wemm <peter@netplex.com.au>, Mike Meyer <mwm@mired.org>, Helge Oldach <Helge.Oldach@de.origin-it.com>, oberman@es.net, mobile@FreeBSD.ORG, stable@FreeBSD.ORG Subject: Re: Disk I/O problem in 4.3-BETA Message-ID: <3AAF4DA0.C8DA9485@paradise.net.nz> References: <200103131007.f2DA73h54023@mobile.wemm.org> <01f001c0abaa$133e1680$4500a8c0@nomad> <20010313032635.Q29888@fw.wintelcom.net>
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What doesn't appear to have been mentioned is how exactly do we turn off write caching on SCSI drives. From poking around the best I could work out was to run 'camcontrol modepage da0 -m 0x08 -e -P 3' and set WCE to 0 where 0x08 comes from /usr/share/misc/scsi_modes. Is this the correct way to do it? Also, is it okay to leave tagged queuing enabled? (I'm really starting to get paranoid after all this discussion!) Cheers, Mark Alfred Perlstein wrote: > > * Mars Attack <marsattack@cannoncreek.com> [010313 02:18] wrote: > > Geez, this thread is getting longer and all the more confusing, can some > > guru possibly attempt to outline the good and bad points of Softupdates or > > WC ? > > 1) softupdates good > 2) WC bad (even when not using softupdates) > > Basically, softupdates doesn't really matter, as long as you have > write caching turned on, you're defeating the safeness of FFS > (noasync) and FFS (softdep) by allowing the disk to reorder what > should be ordered writes. > > -- > -Alfred Perlstein - [bright@wintelcom.net|alfred@freebsd.org] > Daemon News Magazine in your snail-mail! http://magazine.daemonnews.org/ > > To Unsubscribe: send mail to majordomo@FreeBSD.org > with "unsubscribe freebsd-stable" in the body of the message To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-mobile" in the body of the message
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