Tape to Tape Backup.

[Looi Kok Seong]

We are using DLT8000 Tape Drive and fbackup software to do daily full backup. We try to restore one file from this cartrige but it takes so long and we terminate it. But we try to restore other files on the same cartrige and working fine. What we are thinking to do is tape to tape backup in order for us to recover the data. Is it possible to do this kind of backup and how..?
Is there any way for us to recover the data..?

Thanks

[Michael Tully]

Hi,

The first thing you need to do it to establish whether the file your after is in fact on the tape. Create an archive file of the tape contents to verify first.

# frecover -I /tmp/index -f /dev/rmt/0m
(assuming that is your tape device)

HTH
~Michael~

[Looi Kok Seong]

FYI, we already run the command to verify the tape contents and it working fine.
I can see the file we need to restore.

Thanks

[T G Manikandan]

Hello,
If you take veritas or other third patry products as we use veritas I think it has a header or something like that where a restoration is very quick,though it is sequential it skips up the files and locates the right one.
Using a utility like fbackup I think the amount of time to skip the files to locate the exact one it takes time.Might be you have to wait for a longer time for this to get restored.

These are my comments,anyone can correct me if I am wrong
Thanks

[Michael Tully]

Hi,

Since 'fbackup' does not use any type of actual
indexing with default settings the program 'frecover' will still need to find
the actual file you maybe looking for. Most
commercial packages use a database and can stream through the tape much faster to an index point (default).
Now having said all that, it will still depend
on actually where on the tape the file is stored.
Using some of the options available you could
utilise the 'fast search marks' as an option in
the future. Have a look at the man page on
'fbackup' for more info.

Michael

[John Carr_2]

Hi

you can change your backup to use EOF checkpoints this allows frecover to effectively jump through the tape to checkpoints then start a media read unitl it finds the file and restores.
without checkpoints the DLT effectively reads all the tape prior to the required file.

checkout man fbackup & frecover and also read the WARNING on fbackup at bottom of the page.

cheers
John.