Messages in this thread |  | | Date | Wed, 4 Sep 2002 12:37:37 +0200 | From | Andries Brouwer <> | Subject | Re: aic7xxx sets CDR offline, how to reset? |
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On Tue, Sep 03, 2002 at 04:48:39PM -0500, James Bottomley wrote:
> If you're hitting error recovery so often that whether it recovers > in half a second or several seconds makes a difference, I'd say > there's something else wrong.
Not that I want to contradict, but an example. Without my sd.c patch from yesterday or so (fixing MODE SENSE calls) an "insmod usb-storage.o" would take 14 minutes and 6 seconds for me.
[One USB device, with 3 subdevices, gets into a bad state when presented with a MODE SENSE command that asks for more than the 56 bytes it has available. For each of the three subdevices we get a long sequence of retries, abort, reset, host reset, bus reset before it is taken off-line.]
The scsi error recovery has many bad properties, but one is its slowness. Once it gets triggered on a machine with SCSI disks it is common to have a dead system for several minutes. I have not yet met a situation in which rebooting was not preferable above scsi error recovery, especially since the attempt to recover often fails.
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