viewing the contents of an offline backup tape via solaris

Hi,

This very much depends on what you are using to make the backup.  Tools such as Legato and NetBackup have ways to view the Media Catalog, and also to find out what tapes were used for each backup job.

If you are using something like tar or cpio to create a backup and write it to tape, then some commands similar to what you used to create the tape will be needed.

But one important question is: Do you append backups to the end of a tape, or do you overwrite the tape from the start every time?

If you have multiple backups on each tape (each "job" will be a single "tape file"), then you will have to fsf (Forward-Skip-File) first to the correct starting point, probably using the mt command.  (See man mt)

Example - Skip forward 3 files on the tape (In otherwords, to the start of backup job file nr 3 on the tape, with the first one being file nr 0):

mt -f /dev/rmt/0n fsf 3

Note the device "0n" - if you ommit the "n" it defeats the purpose as the tape will rewind again immediately after you complete the forward-skip-file.

Now that the tape is positioned to the correct file start, you can read in the archive "TOC" (Table of contents).

With tar you will typically use something like this:

tar tvf /dev/rmt/0n > /tmp/backupindex

Similarly with cpio:
cpio -itv -I /dev/rmp/0n > /tmp/backupindex

And then use "more" or "less" to browse the backupindex file, eg
less /tmp/backupindex

All of this is pretty standard accross many Unices and versions of Unix.  there are some variations, eg other tools which could have been used to create the backup.  This is probably the most important thing to know.

If you are unsure, try this:

Insert Tape into drive.
Seek to correct file number if it is not the first file on the tape
Then check what type of backup file it is using this command:
file /dev/rmt/0n

The output should tell you what type of file you have, eg USTAR = a tar backup, "cpio" = a CPIO backup, etc.

If you need to skip backwards one file on the tape, add +1 to the number of files to skip backwards.  This doesn't sound liogical, but actually the moment the drive starts to seek backwards for "end-of-file" markers, it immediately encounters the EOF marker where you are positioned at.  This is because FSF will stop "after" the N-th EOF marker.  You therefore need to backward-skip-file by one extra file.

Hope this helps.  The world of tapes is one for the patient amongst us.