Date: Tue, 7 Dec 1999 01:11:41 -0800 (PST) From: Julian Elischer <julian@whistle.com> To: Matthew Dillon <dillon@apollo.backplane.com> Cc: Mike Smith <msmith@FreeBSD.ORG>, cvs-committers@FreeBSD.ORG, cvs-all@FreeBSD.ORG Subject: Re: cvs commit: src/sys/kern kern_shutdown.c Message-ID: <Pine.BSF.4.10.9912070107000.21432-100000@current1.whistle.com> In-Reply-To: <199912070829.AAA75674@apollo.backplane.com>
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On Tue, 7 Dec 1999, Matthew Dillon wrote: > > The disk can lie about whether it has written data to the disk without > messing softupdates up, but it cannot reorder writes that the system has > told it must be ordered. SCSI has a tag to guarentee ordering (or not), > but I don't know if IDE has the same sort of feature. Softupdates ensures the ordering by not isuing a dependent write until it is told that the dependency write has completed. Thus, if the drive says a block is written but it is really in cache, and the system issues another write that depended on the first, the second must not be able to 'overtake' the first. THe safest way to guarantee this is to just not allow the situation to occur. > -Matt > > To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe cvs-all" in the body of the message
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