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Old 1st January 2010, 21:29
kaza kaza is offline
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Default tar backup (multivolume) error message


I attempted to perform a full backup using "tar" and a SCSI tape drive.
The command issued (as a root) was:

tar -cvMPf /dev/st0 --volno-file /root/backup/backup_vol_nums /*

It started OK but after some time (I guess, when the first tape had
been filled up) I've got the error message:

tar: /dev/st0: Cannot close: Input/output error
Prepare volume #2 for `/dev/st0' and hit return:

I attempted to replace the tape and got the error message:

tar: /dev/st0: Warning: Cannot open: No such device or address
Prepare volume #2 for `/dev/st0' and hit return:

From that point and on, the device "/dev/st0" behaved busy
and even the "shutdown" didn't worked - apparently
the system waited until everything had been properly closed
while this device remained opened so I finally had to brutally
power down the system. Reading about SCSI tape device names
I saw that there are few names for the same tape:

/dev/st0 for mode 0
/dev/st0l for mode 1
/dev/st0m for mode 2
/dev/st0a for mode 3

Did I used the correct device name for multi-volume backup with tar?
What is the difference between different modes of accessing the SCSI tape?
Any ideas as to what causes the error message?

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