SAP Note 27367 - SAPDBA volume unreadable, unsupported block size, read

Symptom:

When reading a SAPDBA backup tape, the following error message appears: 'read error on file "/dev/XXX" unsupported block size'.
For example, if you have performed the backup on the TRU64 platform with block size 64 KB (cpio_flags = " -iuv -C 65536"), but then try the restore with 5 KB (cpio_in_flags = -iuvB), the following termination can result: cpio: [offset 5k+0]: Continuing
cpio: [offset 8k+56]: Bad magic number
cpio: initDCI.dba : May be corrupt
cpio: Aborted

Other terms

brbackup, brrestore, brarchive, tape management, tape initialization

Reason and Prerequisites

This occurs, for example, if you initialize a tape and then attempt to read it again.

Solution
In Release 3.0, there is a new parameter in the SAPDBA profile to determine the block size that should be used to read a tape.The profile is in $ORACLE_HOME/dbs and is called init.sap.

The formatting is carried out when writing according to the options of the parameter cpio_flags, the new parameter cpio_in_flags is used for reading.

Parameter values: cpio_flags = -ovB 5k Block size
cpio_flags = -ov -C 16384 16k Block size

cpio_in_flags = -ivB 5k Block size
cpio_in_flags = -iv -C 16384 16k Block size

Make sure that a tape is read with the same block size that it was written with.
If, for example, you attempt to read a tape with a block size of 16k that was written with a block size of 5k, this error message occurs.cpio_flags is usually set to 5k, thus, cpio_in_flags should also be 5k.