Messages in this thread | | | Date | Fri, 14 Mar 2003 06:19:18 -0500 | From | Paul Gortmaker <> | Subject | Re: bio too big device |
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Andries Brouwer wrote:
> We have seen *one* drive (a six years old Maxtor 7850AV) that could not > sustain heavy load with max # secs set to 256, while it behaved better > with max set to 255.
[...]
> Paul remarked: "So the 255 (or even the old 128) fixes things vs. 256, > but I'd feel better being 100% sure why. Is 255 a "fix" or a perturbation > that happens to paper over something else?"
As luck would have it, I kept that drive around, thinking it might be interesting to have around if the above "why" part got revisited someday.
> I think there is no good reason to limit us to 255 sectors. > > (And no reason for blacklists either - there is just no good evidence > that something is systematically wrong with 256 sectors for any brand or > model. Things would change if a second Maxtor 7850AV owner could confirm.)
Perhaps I can also act as the second owner in this case. :-) The drive is currently in an old 16MB P133 on a PIIX3, so after tripping over this thread, I did some testing to 1st see if I could still re-create any problems in this different box. Of note, 2.4.21pre5 reports:
hda: 1667232 sectors (854 MB) w/64KiB Cache, CHS=1654/16/63, BUG DMA OFF -------------------->^^^ which I haven't looked into yet. Anyway, I tweaked pre5 to re-allow 256 and then let it do two 2.5.64 compiles at the same time (in 16MB, this takes a while) and nothing broke. Thinking that the original problem was in an even older VLB box, I disabled DMA and did the same test. Still no breakage.
What does this mean? I'm not sure :) Maybe this simple test isn't as harsh as the prior one from several years ago. Realistically, there are a fair number of changes that also may have a role: e.g. ide driver, gcc, gas, kernel, CPU, mainboard, ide controller, PSU, cables, and so on all have changed. It looks like I would need to jump back into the past and test on the exact same system and then progressively rule out some of these variables. Paul.
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