Trying to determine backup type

[KPS]

Hi,

I have a daunting task of trying to take a VERY old backup tape that was made way before my time and trying to see if we can restore the data on it. My first step is trying to figure out what backup method was used to backup the data. If I index the tape I can see the files on the tape. Is this a good enough indication that fbackup was used way back in the day. The archive is from the year 1996. Are there any better ways to figure out what backup method was used to write the data to tape?

Thanks,
KPS

[James R. Ferguson · Accepted solution]

Hi Ken:

If you think that the tape was created with 'fbackup' try looking at its index and volume header with 'frecover -I' and 'frecover -V' respectively. If its not an 'fbackup' tape, 'frecover' will not process it.

Similarly, you could try listing the contents for 'tar -tvf', etc.

Regards!

...JRF...

[A. Clay Stephenson]

Generally when doing this, I like to first read the 1st 2 blocks or so of the tape and display it using dd. I'll look for hints like "magic numbers" (yes, that is an honest-to-God technical term) not to be confused with "magic cookies" (another real term).

Do this (substituting your actual tape device):

dd if=/dev/rmt/2mn bs=512 count=2 | od -v -Ad -tco > myfile

Examine myfile and look for clues. This is the general approach to identifying backups.


However since you can index the tape that is an extremely good indication (almost certain) that fbackup was used.

[Bill Thorsteinson]

Try running the first block through od.
and see what the header says.

Try the file coammand and see what it says.

You may want to copy the the first 10k or so of the backupp to disk before doing so.

You might have multiple files on the tape
so try forward spacing one file and copying
the first 10k or so of the next file.

[KPS]

Thanks everyone, very helpful