Thanks to those people who give me suggest so rapidly.
my question is:
> I found a strange problem on our magnetic tape devices. Our os is
> DU4.0A,
> We have four magnetic tape devices, and turn off them in evening every
> day.
> After we use them for some days , DU system don't recognize these
> devices.
> After I reboot the system, these tape devices are recognized again.
But
> this
> event often occured irregularly.
> Someone told me not to turn off the magnetictape devices every day
> because the DU advanced file system. will check all of devices
> regularly.
> If the system can't check the devices several times, the systemwill
not
> recognize the devices any more. Is it true? if not true , why ?
the answer is:
This is not tru though advfs does sanity check .
Tape drives are not advfs volumes anyway.
I'd guess that the tape or port driver either
verifies a device is stil present from time to time or gives
up on a device if it gets some number of errors. Now, what could
be happening is that some daemon (perhaps the AdvFS one) is
scanning all the devices to keep an up to date list of the
disks. To decide that a tape special file isn't a disk, it
has to open it, which is probably enough to generate an error,
which the driver may use.
suggestion:
1. Don't turn off the tape drives. Unless they're large 9 track
drives, they're unlikely to use much power compared to the
system and disks.
2. After turning your tape drives on again, use the command:
scsimgr -scan_bus bus=0
(replace bus=0 with the actual bus number where your tapes are connected
two if you have multiple SCSI busses).
in order for the system to recognize them again. This very same
command is run at the system startup as well.
3. Try the "scan edt" command of scu(8) on the bus with the
tape drives and see if that will recover them without a
reboot.
Received on Fri Apr 03 1998 - 11:29:44 NZST