Date: Mon, 12 Mar 2001 15:19:27 -0800 From: Alfred Perlstein <bright@wintelcom.net> To: "J.Goodleaf" <john@goodleaf.net> Cc: stable@FreeBSD.ORG Subject: Re: Disk I/O problem in 4.3-BETA Message-ID: <20010312151927.G18351@fw.wintelcom.net> In-Reply-To: <20010312232046.D24215C09@clyde.goodleaf.net>; from john@goodleaf.net on Mon, Mar 12, 2001 at 11:20:46PM %2B0000 References: <200103122036.VAA99695@freebsd.dk> <200103122146.f2CLkLs08952@ptavv.es.net> <20010312140636.A18351@fw.wintelcom.net> <20010312232046.D24215C09@clyde.goodleaf.net>
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* J.Goodleaf <john@goodleaf.net> [010312 15:10] wrote: > I don't adequately understand the difference between what you're talking > about here and what softupdates does. I have used softupdates for some time, > but now I'm nervous! Can you point me toward the nearest info source, that I > might RTFM and refrain from bugging you guys? (Given that I already tried > man softupdates and man tunefs doesn't tell me anything.) Softupdates depends on the disk not lying about writes completing. Ok, imagine you're a bank. Now imagine you got a bunch of cheap and really fast disks at an amazing price. Ok, one day there's an outtage/crash of some sort. Now, you paid big bucks to make sure that the database was reliable and would recover safely because it made _damn sure_ that before saying "ok, transaction complete" the data was actually written to disk. Now what if these wonderfully cheap and supposedly fast disk were _lying_ to the software about having the data on the actual disk? Well now you really have no idea where you were at the crash bad, eh? Was it really worth all that speed? Just think of a filesystem as a database that _needs_ the underlying disks to be truthful about these things in order to be recoverable after a crash. -- -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
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