On Sunday 18 September 2005 02:03, Jon LaBadie wrote: >On Sat, Sep 17, 2005 at 11:25:48PM -0400, Florian Lengyel wrote: >> Here's the post-mortem: I've been using a hand-me-dowm >> Spectra Logic 2K. No matter what tape I tried in drive 0 >> (the only one of two that my AMANDA configuration seems >> to recognize) I had I/O errors. Even an innocuous command such as >> >> mt -f /dev/nst0 compression off >> >> [by the way, the argument "off" is worth a small fortune in >> consulting fees, since it has to be guessed] >> >> Resulted in an I/O error. Such things are often caused by >> hardware trouble. After checking cables, interface card seating, >> and other things, I tried using the cleaning tape. >> >> Problem solved. > >You wouldn't think a 'compression off' request would have >any involvement with possibly dirty heads. Here is a guess, >I've seen some tape drives that when an error happens flag >the error and refuse to do anything until it is cleared. >At one client they had a DLT drive. Anything went wrong >and the "clean drive" light came on. Then you could do >nothing unless you cleaned it or 'I think' there was some >manual way to turn off the light. Maybe power off/on :)
Thats been the case here Jon. If they have the cleaning flag set, not even a powerdown was able to restore one of those old DDS2 drives for command response. >BTW you mention you have other ?drives? not being seen? >Based on replies here, most linux kernels default to only >scanning LUN 0 on the scsi buss. Some configuation change >lets it scan others. Similarly on my Solaris system, by >default only scsi IDs 0-7 are scanned for tape drives. >Again a config setting allows IDs 8-15 to be scanned. > >Maybe something similar is your problem. Thats been a constant problem for those running Red Hat built kernels, Red Hat doesn't want to waste time scanning for them when only .1% of the users have the scsi stuff in the first place. Linux, I believe, also cheats in that scanning process as even when its turned on (its a kernel config & recompile option), the scsi scan is completed 50x faster than the specs say, which proclaim each device being scanned has 1 second to respond to a query. Thats 49 seconds for all LUNs and all addresses on a scsi-2 narrow bus but linux swings thru that in 3 or 4 seconds. It seems to work most of the time though. -- Cheers, Gene "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) 99.35% setiathome rank, not too shabby for a WV hillbilly Yahoo.com and AOL/TW attorneys please note, additions to the above message by Gene Heskett are: Copyright 2005 by Maurice Eugene Heskett, all rights reserved.
