Date: Mon, 17 Apr 2000 18:56:53 +0530 From: Rahul Siddharthan <rsidd@physics.iisc.ernet.in> To: Rasmus Skaarup <rasmus@gal.dk> Cc: Alfred Perlstein <bright@wintelcom.net>, freebsd-questions@FreeBSD.ORG Subject: Re: disc io - sync and async Message-ID: <20000417185653.A7455@theory6.physics.iisc.ernet.in> In-Reply-To: <Pine.BSF.4.21.0004171300150.10236-100000@skaarup.org>; from rasmus@gal.dk on Mon, Apr 17, 2000 at 01:12:44PM %2B0200 References: <20000416120315.W4381@fw.wintelcom.net> <Pine.BSF.4.21.0004171300150.10236-100000@skaarup.org>
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> If async operations are performed anyhow, why don't we just mount the > drives async from the beginning. If FreeBSD chooses to mount drives in > sync or 'non-async' mode as you say, to increase integrity, and async > operations are performed anyway this doesn't help one bit. You still have > problems with integrity, and the drives will just be slower.. > > Surely we should avoid any kind of breach in integrity, but I mean, a > server breakdown is what it is, and having 200 inodes instead of 300 > inodes corrupted doesn't sound like a worthy result of a much slower hard > drive when the server is up. And even if FreeBSD only performed sync > operations, there would still be some parts of the filesystem that are > corrupted? FWIW, it seems like a machine with low load / few users is not much hit by the performance loss of sync operations, so I've left our FreeBSD machine with its default sync setting, and also changed a linux machine to sync. However, we've had the power fail unexpectedly on plenty of linux machines with async mounts, and never suffered data loss and rarely had even to run fsck manually -- most of the time it does an fsck with automatic corrections and continues happily from there. No "corruption" whatever. So using sync mounts on some machines was only because I've heard that it's safer. For an important server you'd be having stable power, reliable hardware and regular backups anyway -- so it seems to me that async would be preferable in that case, for better performance... To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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