From owner-freebsd-hackers Wed Feb 19 21:51:35 1997 Return-Path: Received: (from root@localhost) by freefall.freebsd.org (8.8.5/8.8.5) id VAA19609 for hackers-outgoing; Wed, 19 Feb 1997 21:51:35 -0800 (PST) Received: from rover.village.org (rover.village.org [204.144.255.49]) by freefall.freebsd.org (8.8.5/8.8.5) with SMTP id VAA19596 for ; Wed, 19 Feb 1997 21:51:31 -0800 (PST) Received: from rover.village.org [127.0.0.1] by rover.village.org with esmtp (Exim 0.56 #1) id E0vxRPT-0006tK-00; Wed, 19 Feb 1997 22:51:11 -0700 To: asami@vader.cs.berkeley.edu (Satoshi Asami) Subject: Re: [Fwd: Failed mail: unknown user] Cc: joerg_wunsch@uriah.heep.sax.de, james@wgold.demon.co.uk, hackers@freebsd.org, dufault@hda.com In-reply-to: Your message of "Wed, 19 Feb 1997 16:52:38 PST." <199702200052.QAA00662@silvia.HIP.Berkeley.EDU> References: <199702200052.QAA00662@silvia.HIP.Berkeley.EDU> Date: Wed, 19 Feb 1997 22:51:11 -0700 From: Warner Losh Message-Id: Sender: owner-hackers@freebsd.org X-Loop: FreeBSD.org Precedence: bulk In message <199702200052.QAA00662@silvia.HIP.Berkeley.EDU> Satoshi Asami writes: : Really? I think drives have their own cache, and if they have write : buffering turned on, they will happily return "write complete" when : they are only holding data in the buffer. Yes. Most modern drives have this feature. : I know Seagate ST15150WC (old Barracuda 4) had the write buffer : disabled, while Quantum 34300WC (Atlas 4) had it enabled. If you : really want to make sure you write through to the platter, either get : one of those that don't have it turned on or turn it off by youself : (I heard it's in one of the SCSI mode pages). Don't know if you can turn it off, but a friend at Conner once told me that they use the drive's momentum to power the rest of the drive long enough to flush out the cache to media, and then they engage the brakes. Warner