Tape drive rewinds forever?

Tape drive rewinds forever?

Post by Mark Morl » Sat, 30 Jan 1999 04:00:00

I just installed an SDT-9000 DAT drive in a SS20 running Solaris 7.  It
seems to work well except for one thing...  When ufsdump is finished and
it starts rewinding the tape, it seems to take forever.  The rewind always
takes longer then the backup itself, and sometimes it never stops
rewinding at all (or rather, we've let it "rewind" for half an hour before
aborting it).  The backup itself is good though, we can restore from it
(the rewind problem doesn't happen with restores).

I've installed the Solaris 7 patch for ufsdump, and the drive works
perfectly in other non-Solaris servers (SunOS and Linux).  It appears that
Solaris is unable to tell when the drive has physically finished

Any ideas?



1. ATAPI Tape Drive Locks With Multiple tar Non-rewind Reads

When trying to read a tar file from a 4Gb ATAPI tape drive the tape
drive locks up after the first read.

The tape contains multiple tar files which were written with:
tar -cvfpPX /dev/nht0 exclude_filename> directory_to_be_tar'ed >>
/tmp/<some filename>
  2>>/tmp<some error filename>

There are no problems with multiple tar writes to the same non-rewinding
tape device.

The read command I use is:
tar -tvf /dev/nht0 > /tmp/some_filename

The first read works correctly but the tape drive light stays on even
after I get a command line prompt.

On the second attempt I almost immediately (1 second delay) get back a
command line prompt.
No read takes place and there are no error messages. It is as if the
tape drive has not been

Sometimes, if I wait a short while, a read attempt will work for the
second tar file on the tape but
attempting to read the third tar file results in a command line prompt
no matter how many times
I try to read it.

An mt rewind command works correctly but a new try has exactly the same
result (first read works
fine but the second doesn't).

Anyone know what the problem is and how to fix it?

Edward Nash Jr.
Senior Technical Support/Unix Analyst
Episcopal Health Services

PS This whole thing started because a tar starting at root creates too
many arguements (/tmp fills up
with a map of the files to be sent to the tape device) than it can
handle. I wanted to split the backup
between the OS filesystems and our application data filesystems using
multiple tar sessions (which
still fails even with large parts excluded from the root tar).

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