Messages in this thread | | | Date | Tue, 16 Sep 1997 23:20:30 +0300 (EET DST) | From | Kai M{kisara <> | Subject | Re: SCSI Tape driver |
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I think this discussion should be moved to linux-scsi.
On Mon, 15 Sep 1997, Richard B. Johnson wrote:
> > To the maintainer of the SCSI Tape Driver, greetings! > I have noticed a problem starting with kernels this early Spring. If > there are any SCSI Tape errors, the errors seem to persist until the > machine is rebooted. > > For instance: > > # cp /dev/zero /dev/st0 > cp: /dev/st0: I/O error > cp: /dev/st0: I/O error ! This fails after a few minutes. > # mt status > SCSI 2 tape drive: ! This doesn't show any errors > File number=0, block number=0, partition=0. > Tape block size 512 bytes. Density code 0x45 (unknown). ^^^^ What drive does this density belong to?
> Soft error count since last status=0 > General status bits on (41010000): > BOT ONLINE IM_REP_EN > # ! Cleaned drive, inserted brand-new tape. > # cp /dev/zero /dev/st0 ! Instantly fails without even attempting to > cp: /dev/st0: I/O error ! access the physical device. > cp: /dev/st0: I/O error
I have tried to recreate this problem in my system. I don't have a broken tape but I modified the mid-level scsi_done function to turn EOM into Medium Error. In my system (Adaptec AHA2940, HP C1533) the errors don't persist. After re-inserting the tape, I can rewrite it without problems.
... > It appears as though the driver "remembers" that there was a previous > command-completion failure and refuses to attempt the command again. > Actually, it's not the driver that remembers, it's the controller. The ^^^^^^^^^^^^^^ or the drive > driver seems to get sense data before each command rather than after, > and refuses to execute the new command because of bad sense data. This bad > sense data was from a previous command. > > Sep 15 10:10:32 chaos kernel: st0: Error with sense data: > Current error st09:00: sns = f0 3 ... > Sep 15 10:10:32 chaos kernel: st0: Error with sense data: > Current error st09:00: sns = f0 3 ... Getting twe same medium error twice is what I expect to happen if the drive finds a medium error: the driver tries to write the closing filemark after the error and this probably also fails.
Kai
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