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    SubjectRe: Possible bug and question about ide_notify_reboot in drivers/ide/ide.c (2.4.19)
    On Fri, 13 Sep 2002, Alex Davis wrote:

    > The cleanup() function in ide-disk.c will flush the write cache. Also, would
    > someone please point me to some documentation that states the cache is flushed
    > when the disk is put in standby: when I called Maxtor about this, they said that

    How about this: The FLUSH CACHE command has only recently become a
    mandatory command for non-PACKET devices, so there may be drives that do
    implement a write cache, but do NOT implement the FLUSH CACHE -- and
    still adhere to some older edition of the ATA standard.

    > the cache is NOT flushed. BTW, if your disk is so broken as to require being put
    > in standby mode to flush its write cache, then you are at great risk for data
    > corruption.

    See above. Disable Write Cache would also do with recent drives.

    IBM specified for the DeskStar 40GV and 75GXP drives (DTLA, I use this
    manual as I have that handy) that Soft Reset, Standby (Immediate) and
    Flush Cache commands would only be executed after the completion of
    writing to media (see the OEM manual, section 10.10 write cache
    function, p.91 in my edition), and goes on "It is recommended that the
    host system verify the completion of the write cache operation by
    issuing Soft reset, the Standby (Immediate) command, or the Flush Cache
    command to the device before power off."

    I think I recall that some notebook drives would need the standby
    immediate to flush the cache to work around firmware bugs with other
    methods.


    If I recall correctly, Windows' shutdown procedure was at some time in
    the past changed to wait a couple of seconds before switching the ATX
    computers off, to allow the drives to flush their caches. I can't quote
    on a KB article though.

    --
    Matthias Andree
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