hi,

We are getting error while trying to restore data using mt command from dds tape.

errors are as follows

mt status
o/p -->

SCSI 2 tape drive
File number=0, blocknumber=0, partition=0
Tape block size 512 bytes, Density code 0x26(DDS-4 or QIC -4GB)
Soft error count since last status=0
general status bits on (41010000)
BOT ONLINE IM_REP_EN

tar -tvf /dev/st0
o/p -->
st0: Incorrect block size
tar: /dev/st0: cannot read: Input/output error
tar: At beginning of tape, quitting now
tar: error is not recoverable ; exiting now

we tried setting blocking factor to 1 (1*512=512)
but still getting same error.

tar -b 1 -tvf /dev/st0 aswellas tar -b 512 /dev/st0
o/p -->
st0: Incorrect block size
tar: /dev/st0: cannot read: Input/output error
tar: At beginning of tape, quitting now
tar: error is not recoverable ; exiting now

please help.
I don't understand what does block size means.

Block size means the same thing on tape as it does on disk. I'm not sure what format dds refers to. I'm familiar with DAT and DLT as being the most popular formats to use in business. DLT tapes typically use a block size of 32768 bytes.

Try using a tape cleaning cartridge, then try to reread the tape.

And, does this only happen on one tape or several? Tapes go bad after a few years.