From owner-freebsd-questions Mon Apr 17 6:27:31 2000 Delivered-To: freebsd-questions@freebsd.org Received: from theory1.physics.iisc.ernet.in (theory1.physics.iisc.ernet.in [144.16.71.20]) by hub.freebsd.org (Postfix) with SMTP id 9C52B37B527 for ; Mon, 17 Apr 2000 06:27:14 -0700 (PDT) (envelope-from rsidd@theory6.physics.iisc.ernet.in) Received: (qmail 1248 invoked from network); 17 Apr 2000 13:26:55 -0000 Received: from unknown (HELO theory6.physics.iisc.ernet.in) (qmailr@144.16.71.126) by theory1.physics.iisc.ernet.in with SMTP; 17 Apr 2000 13:26:55 -0000 Received: (qmail 7486 invoked by uid 211); 17 Apr 2000 13:26:54 -0000 Date: Mon, 17 Apr 2000 18:56:53 +0530 From: Rahul Siddharthan To: Rasmus Skaarup Cc: Alfred Perlstein , freebsd-questions@FreeBSD.ORG Subject: Re: disc io - sync and async Message-ID: <20000417185653.A7455@theory6.physics.iisc.ernet.in> Mail-Followup-To: Rasmus Skaarup , Alfred Perlstein , freebsd-questions@FreeBSD.ORG References: <20000416120315.W4381@fw.wintelcom.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Mailer: Mutt 1.0.1i In-Reply-To: ; from rasmus@gal.dk on Mon, Apr 17, 2000 at 01:12:44PM +0200 X-Operating-System: Linux 2.2.15pre4 alpha Sender: owner-freebsd-questions@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG > 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