QUESTION:
Can the RS/6000 1/4" tape drive read a tape created by an AS/400? The
AS/400 tape will be in a data interchange format, labeled or unlabeled.
Does the RS/6000 require any additional software, besides AIX, to read
this tape?
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A: I was unable to find any specific RISC System/6000 tools for
interpreting tapes created on an AS/400. However, many people
have successfully transferred data from an AS/400 tape to the
RISC system by using the "dd" command.
Here are several things to be aware of:
o You will need to have similar tape devices attached to both
machines (i.e. 8mm on both machines, 1/4 inch on both machines).
o The data on the AS/400 tape needs to be EBCDIC, not packed
decimal, so that "dd" can read the EBCDIC fixed length records
and convert them to ASCII variable length records.
o If you're using CRC checking on the AS/400, turn it off.
o If possible, try not to use labels when making the tapes on the
AS/400. If you did NOT use labels on the AS/400, you can
read the tapes with the command:
dd if=/dev/rmtX of=/mydir bs=blocksize cbs=blocksize conv=ascii
"conv=ascii" converts EBCDIC to ASCII
"bs" is the blocksize of both input and output media, must
be multiple of physical block size of both media (ie. 512).
"cbs" is the conversion blocksize, should be set to the
max_rec_length on the ebcdic tape (ie. 80).
o The AS/400 cannot write to a 1/4" tape without putting a
standard label on the tape. If you have used labels and are
restoring on the AIX side, the "dd" command can skip over the
label on front of the tape with the "fskip=1" flag. For
example:
dd if=/dev/rmtX of=/mydir bs=blksz cbs=blksz conv=ascii fskip=1
o Any record headers on the data would need to be converted to new-
line characters.
o If you try to read MULTIPLE files off the AS/400 tape, "dd"
will read and store all data until a second end-of-file marker
is read. When dd saves the data to a file, it does not
add markers to distinguish one file from another. You will need
to write a program to separate the data back into the different
files.
o You will need to also choose your block size parameters
correctly. When restoring the tape, the block size needs to be
set to the same value as the block size used in making the tape.
Make sure the physical block sizes on the tape devices are the
same, preferably 512 for the 1/4 inch tape drive. The tape needs
to be read at the same block size that it was written.
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This item was created from library item Q635054 CHVSF
Additional search words:
ANS AS400 AUG93 CHVSF CREATED DD EBCDIC HARDWARE HELD HOLD IX LABEL
OZNEW RDR READ READER READS RISC RISCOHW RISCSYSTEM TAPE 400 6000
WWQA: ITEM: RTA000032875 ITEM: RTA000032875
Dated: 04/1996 Category: RISCOHW
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