Messages in this thread |  | | From | Nicholas Knight <> | Subject | Re: [PATCH] 2.4.10 improved reiserfs a lot, but could still be better | Date | Tue, 25 Sep 2001 04:07:47 -0700 |
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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. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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