Date: Mon, 24 Sep 2001 06:52:11 -0700 From: Cy Schubert - ITSD Open Systems Group <Cy.Schubert@uumail.gov.bc.ca> To: Pete French <pfrench@firstcallgroup.co.uk> Cc: stable@FreeBSD.ORG Subject: Re: regarding tyhe recent disc drives conversation... Message-ID: <200109241352.f8ODqMc07962@cwsys.cwsent.com> In-Reply-To: Your message of "Mon, 24 Sep 2001 10:28:38 BST." <E15lS2Y-0005AQ-00@mailhost.firstcallgroup.co.uk>
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In message <E15lS2Y-0005AQ-00@mailhost.firstcallgroup.co.uk>, 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
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