From owner-freebsd-stable Mon Sep 24 6:53:13 2001 Delivered-To: freebsd-stable@freebsd.org Received: from point.osg.gov.bc.ca (point.osg.gov.bc.ca [142.32.102.44]) by hub.freebsd.org (Postfix) with ESMTP id 3BC8737B414 for ; Mon, 24 Sep 2001 06:53:08 -0700 (PDT) Received: (from daemon@localhost) by point.osg.gov.bc.ca (8.8.7/8.8.8) id GAA31209; Mon, 24 Sep 2001 06:53:05 -0700 Received: from passer.osg.gov.bc.ca(142.32.110.29) via SMTP by point.osg.gov.bc.ca, id smtpda31207; Mon Sep 24 06:52:52 2001 Received: (from uucp@localhost) by passer.osg.gov.bc.ca (8.11.6/8.9.1) id f8ODqqP27323; Mon, 24 Sep 2001 06:52:52 -0700 (PDT) Received: from UNKNOWN(10.1.2.1), claiming to be "cwsys.cwsent.com" via SMTP by passer9.cwsent.com, id smtpdx27321; Mon Sep 24 06:52:22 2001 Received: (from smtpd@localhost) by cwsys.cwsent.com (8.11.6/8.9.1) id f8ODqMc07962; Mon, 24 Sep 2001 06:52:22 -0700 (PDT) Message-Id: <200109241352.f8ODqMc07962@cwsys.cwsent.com> X-Authentication-Warning: cwsys.cwsent.com: smtpd set sender to using -f Received: from localhost.cwsent.com(127.0.0.1), claiming to be "cwsys" via SMTP by localhost.cwsent.com, id smtpdfJ7196; Mon Sep 24 06:52:11 2001 X-Mailer: exmh version 2.5 07/13/2001 with nmh-1.0.4 Reply-To: Cy Schubert - ITSD Open Systems Group From: Cy Schubert - ITSD Open Systems Group X-Sender: schubert To: Pete French Cc: stable@FreeBSD.ORG Subject: Re: regarding tyhe recent disc drives conversation... In-reply-to: Your message of "Mon, 24 Sep 2001 10:28:38 BST." Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Date: Mon, 24 Sep 2001 06:52:11 -0700 Sender: owner-freebsd-stable@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG In message , Pete French write s: > is thhere any advantage to be gained by mounting a disc synchronous, but with > soft updates enabled ? will not the effect o softupdates be to cancel out > any benificial effects of having the data written to the disc synchronously > as the meta data that describes it will not be written out until some > later time - thus if a power outage occurs the data will still be lost ? Mounting disks sync/async and softupdates are mutually exclusive. Once the softupdates flag has been set in the superblock a filesystem cannot be written to synchronously or asynchronously. You can think of softupdates as ordered synchronous metadata writes asynchronously. Metadata is written asynchronously to memory, ordered, then written out synchronously in batches in such a way that it is only 3% slower than asynchronously written metadata, giving you virtually the speed of asynchronous metadata writes with the reliability of synchronous metadata writes. I supposed I've made it as clear as mud. Regards, Phone: (250)387-8437 Cy Schubert Fax: (250)387-5766 Team Leader, Sun/Alpha Team Internet: Cy.Schubert@osg.gov.bc.ca Open Systems Group, ITSD Ministry of Management Services Province of BC To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message