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    SubjectRe: [PATCH] 2.4.10 improved reiserfs a lot, but could still be better
    On Tuesday 25 September 2001 03:42 am, Matthias Andree wrote:
    > On Mon, 24 Sep 2001, Nicholas Knight wrote:
    > > It's a very remote possability of failure, like most instances
    > > where write-cache would cause problems. Catastrophic failure of the
    > > IDE cable in mid-write will cause problems. If write cache is
    > > enabled, the write stands a higher chance of having made it to the
    > > drive before the cable died, with it off, it stands a higher chance
    > > of NOT having made it entirely to the drive.
    > Cables don't suddenly die without the help of e. g. your CPU fan.

    I explained in another message the situation I was thinking of,
    accidental pulling of the cable.

    > > For most drives, I don't know for sure if they'd finish the write
    > > that's now sitting in their cache, but I expect higher quality
    > > drives (such as our IBM drives) definitely would. Infact I may even
    > > be willing to test this later (my swap partition looks like it
    > > wants to help :)
    > Drives would not write incomplete blocks.

    Not what I ment, I ment that if a write gets to the drive completely,
    and part is still sitting in the cache, I'd think the drive would
    continue to write it out as long as it has power. I wasn't reffering to
    the write partialy being down the cable.

    > >
    > > Either Maxtor or Western Digital share very close designs to IBM
    > > drives, I belive they had some sort of development partnership. I'm
    > > not sure if it was Maxtor or WD.
    > The Western Digital 420400D (20 GB, 5400/min) and its 7200/min
    > brother with 18 GBs were IBM disk drives, supposedly, but the WD
    > ...AA/BB drives and whatever else there was looked some different
    > from IBM drives.
    > > > Why are disk drives slower with their caches disabled on LINEAR
    > > > writes?
    > >
    > > Maybe the cache isn't doing what we think it is?
    > Maybe. A monitor software or debug mode would be good to see when
    > writes are scheduled and which blocks are written (I need to ask a
    > friend of mine who hacked ll_rw_blk.c on a different purpose for his
    > diploma thesis, maybe his code is valuable to figure things out.)
    > > Does anyone have contacts at IBM and/or Western Digital?
    > > Something's up... The 256MB write with write-cache off was going at
    > > 5.8MB/sec, and with it on it was going at 14.22MB/sec (averages).
    > > One interesting thing, the timings are showing a pretty consistant
    > > but tiny increase in sys time with write caching on.
    > I also saw that here, but again, it's basically the same hardware.
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