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    SubjectRe: [PATCH] 2.4.x write barriers (updated for ext3)
    Hi Doug,

    On Sun, Mar 10, 2002 at 12:24:12AM -0500, Douglas Gilbert wrote:
    > "Stephen C. Tweedie" wrote:
    > > Even if WCE is enabled in the caching mode page, we can still set FUA
    > > (Force Unit Access) in individual write commands to force platter
    > > completion before commands complete.
    > >
    > > Of course, it's a good question whether this is honoured properly on
    > > all drives.
    > >
    > > FUA is not available on WRITE6, only WRITE10 or WRITE12 commands.
    > Stephen,
    > Also SYNCHRONIZE CACHE(10) allows a range of blocks to be sent
    > to the platter but the size of the range is limited to 2**16 - 1
    > blocks which is probably too small to be useful. If the
    > "number of blocks" field is set to 0 then the whole disk cache
    > is flushed to the platter.

    Which I think we should send before shutdown (and possible poweroff) for
    disks (DASDs), Write-Once and Optical Memory devices. (Funny enough, the
    SCSI spec also lists SYNCHRONIZE_CACHE for CD-Rom devices
    Unfortunately, SYNCHRONIZE CACHE is optional, so we would need to ignore any
    errors returned by this command.

    Kurt Garloff <> Eindhoven, NL
    GPG key: See mail header, key servers Linux kernel development
    SuSE Linux AG, Nuernberg, DE SCSI, Security
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