byte swap notice when using dds tape - Printable Version
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+--- Thread: byte swap notice when using dds tape (/thread-4566.html)
byte swap notice when using dds tape - tallen - 06-27-2025
Hi have been extracting some older data from my dds drive unit (Sony SDT S9000) and using a "tar -xvf" command (as I did many years ago).
I have successfully extracted all but one dds tape, and one was corrupt. So for the remaining dds tape that does show up as corrupt but rather a notice, please if you can help me decipher? It's not an error or a fail, but the results are the same, it's not extracting.
(and the command below makes the assumption that the drive is mounted and again, this has worked for several tapes over the past few weeks, except this one tape)
tar -xvF (enter)
tar: directory check sum error
tar: this appears to be a byte-swapped archive.
Any ideas on what would bring up a "byte-swapped archive" notice? I am pretty sure I always used a tar command for storage, but it was so long ago. It is entirely possible I could have used another method.
RE: byte swap notice when using dds tape - Raion - 06-27-2025
IRIX is big endian, most other operating systems are little endian. Is it possible that the tape wasn't made on IRIX?
RE: byte swap notice when using dds tape - robespierre - 06-27-2025
If you read the man page for mtio(7) and tar(1), they discuss how IRIX's default tape device is byte-swapped. This is historical, for compatibility with the IRIS 2000 which had a byte-swapped tape interface.
By specifying the non-swapped device, /dev/tapens (for example, by using the "f" option to tar), you can get the alternative behavior which may be more compatible with other systems like Sun.
The tar(1) page also gives a pipeline using dd(1) with the conv=swab option, as an alternative way to reverse byte-swapping.
Code:
tar tf /dev/tapensRE: byte swap notice when using dds tape - tallen - 07-01-2025
thanks I'll try these options.