Date: Thu, 20 Sep 2001 22:27:27 -0500 From: "David W. Chapman Jr." <dwcjr@inethouston.net> To: "Brandon S. Allbery KF8NH" <allbery@ece.cmu.edu> Cc: "David W. Chapman Jr." <dwcjr@inethouston.net>, Daniel O'Connor <doconnor@gsoft.com.au>, Nuno Teixeira <nuno.mailinglists@pt-quorum.com>, freebsd-stable@FreeBSD.ORG Subject: Re: hw.ata.wc && hw.ata.tags && softupdates short question Message-ID: <20010920222727.E78811@leviathan.inethouston.net> In-Reply-To: <107060000.1001041983@vpn58.ece.cmu.edu> References: <20010920211704.C7820@gateway.bogus> <XFMail.20010921121832.doconnor@gsoft.com.au> <20010920215107.B78811@leviathan.inethouston.net> <107060000.1001041983@vpn58.ece.cmu.edu>
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On Thu, Sep 20, 2001 at 11:13:04PM -0400, Brandon S. Allbery KF8NH wrote: > On Thursday, September 20, 2001 21:51:07 -0500, "David W. Chapman Jr." > <dwcjr@inethouston.net> wrote: > +----- > | > Well you can but if you lose power you WILL lose data. > | > > | Doesn't harware write cache usually write itself to disk before power > | outage or even after? > +--->8 > > My understanding is that modern drives typically have such large caches > that they can't actually guarantee flushing the entire cache to disk on > power failure before the capacitor(s) that store power for the purpose > discharge. You might be lucky if the cache is relatively empty, or you > might lose. > I'm just speculating, but on my drive with 2mb cache, that can sustain 20-30mb/sec writting, that's a tenth of a second. But my drive isn't the typical home user drive. -- David W. Chapman Jr. dwcjr@inethouston.net Raintree Network Services, Inc. <www.inethouston.net> dwcjr@freebsd.org FreeBSD Committer <www.FreeBSD.org> To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message
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