Well, I figured this out and I promised myself that when I did, I would share the information so that no one else has to figure it out on their own.
When using the -v -B options in afio, it tells you the byte offset of each file in the archive. Here is an example on how to use that information. This example also assumes you are using the default block size for afio (5120). I used an HP Surestore SCSI Tape Drive / DDS3 Tape for this example too. The following line comes from the -v -B output of afio: 10750485482 data/testfile.z -- (65%) The number 10750485482 tells you that the file data/testfile.z is that many bytes (10.7 GB) into the archive (In this example, it is the last file in the archive too). If you were to use the typical command: afio -i -v -y "data/testfile*" /dev/st0 to restore that file, it would start at the beginning of the tape and "search" for any afio header information matching that search criteria and then restore it. In this case, it would take just over 3 hours to restore that one file (the same amount of time it would take to restore this entire archive) because it has to read the entire tape to find files matching that search criteria. Now, if you have a SCSI-2 tape device which supports the 'mt -f /dev/st0 seek' command, you can dramaticly reduce the amount of time to do selective file restores. If you want to restore the entire tape, then you are stuck with however long it takes (in this case, 3 hours). You take the byte offset of the file you want to restore (10750485482) and divide it by your block size (5120) to get the block location of this file (2099704.19). Just drop everything after the decimal (Never round up or you will end up going past the file location), so we end up with 2099704 which you use in the following commands: Rewind the tape: mt -f /dev/st0 rewind Fast forward to the location you want to start the restore from (nst0 instead of st0 because we don't want it to rewind the tape after the command finishes): mt -f /dev/nst0 seek 2099704 Start the restore with afio (You need the -k option so afio doesn't fail because it will start searching part way through the previous file in the archive): afio -i -v -k -y "data/testfile*" /dev/st0 You can replace /dev/st0 with /dev/nst0 in the last command if you don't want it to rewind the tape after which is useful if you want to restore another file after the current file location. So, how long did it take to restore this exact same file using this better method? 1 minute & 17 seconds, compared to 3 hours the other way. Hopefully this helps someone else who may have been searching for the same solution. Cheers, Trevor _______________________________________________ clug-talk mailing list [EMAIL PROTECTED] http://clug.ca/mailman/listinfo/clug-talk_clug.ca
