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Conference turris::digital_unix

Title:DIGITAL UNIX(FORMERLY KNOWN AS DEC OSF/1)
Notice:Welcome to the Digital UNIX Conference
Moderator:SMURF::DENHAM
Created:Thu Mar 16 1995
Last Modified:Fri Jun 06 1997
Last Successful Update:Fri Jun 06 1997
Number of topics:10068
Total number of notes:35879

8530.0. "v3.2b and tar block sizes" by NETRIX::"[email protected]" (Kim Roy) Tue Jan 21 1997 16:48

T.RTitleUserPersonal
Name
DateLines
8530.1NABETH::alanDr. File System's Home for Wayward Inodes.Tue Jan 21 1997 17:2611
8530.2IOSG::MARSHALLTue Jan 28 1997 12:4027
Maybe my memory is way off track (it's a few years since I did anything serious
with Unix and tapes, (and the Federal Charges were dropped :-)), but in my
experience:

- writing a tape with a non-optimal (for the device) block size does nothing
worse than slow down the writes (eg it might prevent the tape device from
'streaming')

- reading a tape with a different block size from that with which it was written
similarly does nothing worse than slow down the reads.

Anything that is completely unable to read a tape on Unix due to block size
differences is doing something very weird; the whole idea of Unix special
devices is to make it easy to do this sort of thing.

If you were using the block (structured) special device, try using the character
(unstructured) device instead, or vice-versa.

Or you could always try the following, which almost seems too na�ve and simple,
but has worked for me in the past:

- a few 'mt' commands as necessary to position at the correct file on tape
- cp /dev/rmt0 /tmp/tapefile  (or whatever your tape device is called)
- tar xf /tmp/tapefile  (as the tar archive is now on disk, the block size no
                         longer matters)

Scott