On Tuesday 10 June 2003 09:16, Tom Yates wrote: >On Mon, 9 Jun 2003, Eric Siegerman wrote: >> Well, "SCSI parity error" seems pretty clear -- data being >> received with bad parity by one of your SCSI devices (either the >> tape drive or the SCSI adapter; I'm being carefully agnostic as >> to which way the data's flowing when the errors are detected). >> Most likely the corruption is occurring on the SCSI bus. The >> only other possibility I can think of is a firmware bug or other >> malfunction in one of the two devices. > >seems reasonable. > >> > can you think of any other non-amanda test i can do that will >> > exercise the tape drive as amanda does? >> >> Only what I've already suggested -- use real disk files instead >> of /dev/urandom as your data source. Based on what I'm about to >> say, it'd be wise to make sure those files come from the same >> drive your Amanda holding disk is on. To get as close as >> possible to what Amanda's doing, use the holding-disk files >> themselves. > >ok, i did this (made a big disc file from /dev/urandom, then dd'ed > that to the tape), and it still works fine. i emphasise that my > discs aren't on the same SCSI bus as the tape drive - the tape > drive has its own controller, which no other device uses - but > still no errors came. i dd'ed around 2GB of data to the tape, and > had no problems at all. > >> If, as I suspect, the problem is noise on the SCSI bus, one ugly >> possibility is that your SCSI cable is picking up noise from the >> rest of the system; for example, from the IDE cable that your >> disk is connected to. No disk I/O => no noise being transmitted >> => no SCSI errors. > >hopefully, this test has disproved that theory. > >> The obvious first stab at an answer would be to just move the >> cables around inside the case, hoping to get the SCSI cable far >> enough away from the noise source. But *please* figure out how >> to duplicate the problem first, otherwise you'll never know if >> you fixed it! > >at the moment, duplicating it is *really* easy. any time the amanda > taper tries to write to the tape, nothing works (write errors in > the first gigabyte). the rest of the time, i can send data to the > tape just fine. > >> A better solution (if this is indeed the problem!) would be >> better-quality SCSI cables. > >so noted. > >> This is the sort of problem I *hate*! Best of luck with it. > ><grin> thanks for your ideas! does anyone else have any > suggestions, at all, for a tape drive which seems to be fine until > amanda uses it, and which then goes south fairly rapidly? > Blocksize clashes with a tape drive that doesn't use a variable block size maybe? I'm just learning about that myself. Post an "mt -f /dev/device status" please.
>does anyone know anything about decoding kernel SCSI error messages? Not here, but you might post a few lines of it, it might ring someones bell :) -- Cheers, Gene AMD [EMAIL PROTECTED] 320M [EMAIL PROTECTED] 512M 99.26% setiathome rank, not too shabby for a WV hillbilly Yahoo.com attornies please note, additions to this message by Gene Heskett are: Copyright 2003 by Maurice Eugene Heskett, all rights reserved.
