Coda File System

Re: Backup problems

From: Jan Harkes <>
Date: Tue, 14 Dec 1999 11:51:07 -0500
On Tue, Dec 14, 1999 at 11:39:34AM +0100, Kurt Huwig wrote:
> Hello!
> I have several problems with backing up the coda filesystem:
> 1. ''
>     $rc = 0xffff & system("dump 0sBf $blocksize $size $tape $part");
> The option '-s' sets the tape length and not the blocksize; '-B'
> overrides '-s', so this should read 'dump 0bBf' with '$blocksize' <= 64
> (currently 500).

Funny, it's been working fine here, but you are right that the options
we pass to dump don't seem to make much sense :) Even the `B' option is
the number of records, so it should probably be divided by $blocksize.

> 2. The '' script is missing. Where can I get it from?, old documentation. At least, I've never seen it, only the
reference to it in the Coda-manual. Restore sequence is:

- Locate an restore the last backup using the backuplogs.
    In the log is has the command to restore the volume dump.
    The /backup partition is just a bunch of symlinks and can be ignored.

    ---------> Partition /backup1:
    ---------> command: mt -f /dev/nst0 rewind
    ---------> command: restore -b 500 -s 2 -f /dev/nst0 -t /

    Which translates into:

    cd /backup1
    mt -f /dev/nst0 rewind
    restore -b 500 -s 2 -f /dev/nst0 -i
				     ^^ interactive

    Select the volumes to restore, and wait a while...

- If the restored dump was an incremental, locate the last full dump.
    Same steps as above to restore and then merge the two volume dumps.

    merge /restore/restored.volume /backup2/28Aug1998/f0000427.ce000011 \

- Put the volume on a coda server.
    volutil -h <server> restore /restore/restored.volume /vicepa \

- Mount the volume, it is sadly still read-only and the only way of
  getting the data on a rw-replicated volume is to copy it over.

> 3. Does anyone know what is the 'modified Tower of Hanoi algorithm'
> mentioned in the dump(8)-manpage?

Coda's volume dumps should always be backed up at level 0 from the
holding disks (the backup-server). The incrementals etc. are done
within the fileservers, currently Coda only knows about full dumps
(level 0) and level 1 incrementals.

As far as the modified Tower of Hanoi, a bit of googling later....
| This schedule, although slightly complex, requires that you restore at
| most four tapes at any point in the month if a system failure corrupts
| files. Of course, doing a level 0 dump daily requires that you restore
| at most one tape at any point, but requires a large amount of time and
| tape storage for each backup. On most days in the Tower of Hanoi
| schedule, very little time and tape storage are required for a backup.

Received on 1999-12-14 11:57:14