Dump

[Joshua Oreman]

On Mon, Sep 01, 2003 at 10:15:08AM -0400 or thereabouts, Michael Alestock wrote:
> I had a question....
> 
> I have 4 filesystems that I want to dump(8) to my SCSI Tape backup drive 
> (Travan 4GB uncompressed).  The filesystems are, "/", "/usr", "/var", and 
> "/usr/home."  All four filesystems equal about 2.5Gigs of data.
> 
> I dumped the first filesystem "/" by executing, "dump -0uf /dev/sa0 / " 
> ....then executed, "mt -f /dev/sa0 eom" to move the tape to the end of the 
> backup (to append to the tape), then dumped the second filesystem (/usr) 
> using,"dump -0uf /dev/sa0 /usr".  Then once again I executed, "mt -f 
> /dev/sa0" to move the tape to the end (to append to it).
> 
> When I go to execute, "restore -if /dev/sa0" to confirm that both filesystems 
> were saved so far, there's only ONE filesystem saved to the tape "/".  I 
> can't 'cd' to /var because it's not on the tape.  What am I doing wrong???  I 
> know I still have plenty of tape left to save other filesystems, but it's not 
> dumping anything after the first filesystem.
> 
> Any ideas as to what I'm doing wrong??

First, no need to run eom.

So backup goes like this:
# for FS in / /usr /usr/home /var; do
> dump -0uf /dev/sa0 $FS
> done && mt -f /dev/sa0 rewind

To restore, you have to skip the tape to the correct position (read up on mt fsf).
Then you can run `restore if /dev/sa0' to get files from *THAT PARTITION ONLY*.
So if you wanted to restore a file in / but not /var or /usr (assuming rewound tape),
do:
# restore -if /dev/sa0
like you tried.
To restore a file on /usr (assuming above order) on a rewound tape, do:
# mt -f /dev/sa0 fsf
# restore -if /dev/sa0
To restore a file on /usr/home, rewound tape, do `fsf 2'.
To restore a file on /var and rewound tape, use `fsf 3'.
To rewind the tape:
# mt -f /dev/sa0 rewind

It may be useful to keep a catalog as the first file on the tape. So you might want to
do something like this before a backup of multiple file systems on one tape:

# mt -f /dev/sa0 erase  # CAREFUL! this erases previous backup!
# dd of=/dev/sa0 <<EOF
Backup of `hostname` made on `date +%D`

sector 0: this catalog
fsf    1: /
fsf    2: /usr
fsf    3: /usr/home
fsf    4: /var
EOF
# dump 0uf /dev/sa0 /
# dump 0uf /dev/sa0 /usr
# dump 0uf /dev/sa0 /usr/home
# dump 0uf /dev/sa0 /var
# mt -f /dev/sa0 rewind

Using this kind of thing, you can see exactly where each backup is located.
To get to a certain backup, do:
# mt -f /dev/sa0 rewind
# dd if=/dev/sa0
<catalog will be output>
<assumes you want to restore a file from /usr/home, fsf 3>
# mt -f /dev/sa0 fsf 3
# cd /usr/home
# restore if /dev/sa0

Note that when restoring a file system other than /, paths are relative to the
root of that filesystem. So, for example, if you're restoring from /usr backup,
then /usr/X11R6 is actually /X11R6. /home will be there, but empty (it's a mount
point).

Also, in the above catalog, file numbers really start at 1; I was simplifying it
so it would be easy to see exactly what you need to give to mt.

-- Josh

> 
> 
> Thanks,
> 
> >>> Michael
> 
> 
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