Restoring files (old)

This section describes how to restore files backed up with Amanda either with or without Amanada tools. The section has presented as multiple examples. Read the whole section and use the example that is most applicable to your situation

Assumptions

• All the examples below discuss restoration of a complete disk, that is, replacing a bad disk with a new one, or created a new filesystem on top of old one. Changing the restore arguments (not amrestore), individual files can be restored.

• Also, this section does not cover amrecover, a program that provides a text user interface similar to interactive restore (restore -i), but it allows you to select individual files to recover and automatically determines the tapes where they were stored. The backups must be performed with the `index' option enabled for this to work.

• All the examples below assume the backups were done using DUMP program. Backups done using GNUTAR can be restored in similar manner. Instead of using restore command, gtar command will have to be used.

Examples

The server machine is called Aaron, the client machine is called Barney. Backup is being restored to Barney

Example 1: Client machine fails, non-system critical

Example: /home fails on Barney.

• Use amadmin to find the tapes most recently used to backup the partition.

# amadmin <config> info Barney '/home$'

Current info for Barney /home:
 Stats: dump rates (kps), Full:   41.1,  33.1,  38.8
                   Incremental:    9.5,   2.1,  24.7
         compressed size, Full:  63.1%, 54.0%, 52.9%
                   Incremental:  43.7%, 15.5%, 47.8%
 Dumps: lev datestmp  tape             file   origK   compK secs
         0  19971223  Barney01           16  329947  208032 5060
         1  19980108  Barney16            8    1977     864   91
         2  19971222  Barney06            7    1874     672   83
         3  19970926  Barney03           11   12273    3040  211 

Above information shows that two tapes are needed to do a full restore (Barney01, Barney16). Note that, even if Barney06 and Barney03 are listed, they are actually older than the full backup, so they should not be used to restore any data.

• Log into Barney. Cd to the /home directory.

• Insert the tape with the level 0 dump on it into the tape drive of Aaron.

• Become super-user in the Barney and run (replace <amanda> with the username under which amanda runs):

rsh -n -l <amanda> Aaron amrestore -p /dev/rmt/0cn Barney '/home\$' |
restore -ivbf 2 -

This step requires client root to have login access to <amanda>@Aaron, with a .rhosts entry (.amandahosts won't do). If you use ssh, you may be able to type a password in order to be authenticated. Another alternative is to start the operation in the server, and rsh to the client. You should be the amanda user or root in the tape server and run:

amrestore -p /dev/rmt/0cn Barney '/home$' |
rsh Barney -l root /usr/etc/restore -ivbf 2 - 

If you don't want to use rsh at all, you may run:

amrestore /dev/rmt/0cn Barney '/home$' 

• This should create a file whose name contains the hostname, directory name, dump level and dump date of the backup. Now you have to move this file to the client somehow: you may use NFS, rcp, ftp. Suppose you rename that file to `home.0'. Then, on the client, you should become root and run:

restore -ivbf 2 home.0 

• Repeat one of these steps, incrementing the level of the dump, until there are no more available backups.

Example 2: Client machine fails, system critical disk

Example: / fails on Barney.

• Boot off the CD, and reinstall the system critical partition, restoring it to vendor supplied state.
• Go through all steps in Example 1.

Example 3: Server machine fails, non-system critical, non-AMANDA disk

• Proceed with steps described in Example 1.

• However, the rsh process need not be used. Use amrestore to replace the lost data directly.

Example 4: Server machine fails, system critical, non-AMANDA disk

Example: / on Aaron

• Boot off the CD, and reinstall the system critical partition, restoring it to vendor supplied state.

• Follow steps in Example 3.

Example 5: Server machine fails, non-system critical, AMANDA disk, with db

Example: /etc on Aaron

• If the disk that contains the AMANDA database is bad, then you need to rebuild the database.

• Use the text file that is mailed using the 'amadmin <config> export' command, and import via the 'amadmin <config> import' command.

• Follow the steps outlined in Example 4.

 * Note that Amanda does not mail the exported database automatically. 
   Create a crontab entry to do 'amadmin <config> export'

 * It is a good idea to print out the text files as well and store the 
   last 2 dumpcycles information.

Example 6: Server machine fails, non-system critical, AMANDA disk, with binaries

Example: /usr/local on Aaron

If the disk with the amanda binaries is bad, there are three options.

1. Reinstall the Amanda binaries from another tape or RPMs, on which you have conveniently backed up the binaries within the last couple of weeks (not using Amanda).
2. Recompile Amanda, making sure not to overwrite your db files.
3. Use dd to read Amanda formatted tapes. Amanda stores dump in client format and can be restored using client tools.

1. Find out the device name used by Amanda, by looking in amanda.conf. Example: /dev/rmt/0cn. If amanda.conf is not available, this must be a non-rewinding tape device. (the trailing `n' stands for non-rewinding tape device).

2. Look at a copy of the output of 'amadmin <config> export', and find out which tapes /usr/local was backed up on.

3. Grab the tapes that /opt was backed up on, and put the level 0 into the tape drive. cd to /usr/local.

4. Skip the first record, which is just the tape header, by using the appropriate tape command.

mt -f /dev/rmt/0cn fsf 1

5. Look for /usr/local on this tape.

dd if=/dev/rmt/0cn bs=32k skip=1 | gzip -d | /usr/sbin/restore -ivf -

This command provides interactive restore of this record, including partition, host, and level the backup was. The gzip -d portion of the pipe can be omitted if there was no compression.

6. If /usr/local could not be found, quit restore, and move forward one record.

mt -f /dev/rmt/0cn fsf 1

and try the dd/restore command shown above. Do this until you find /opt on the disk.

• Another option is to create a quick tape index in case information about which partition /usr/local was on is not available.

#!/bin/sh
TAPEDEV=/dev/nrtape
while mt -f $TAPEDEV fsf 1 ; do
 dd if=$TAPEDEV bs=32k count=1 | head -1
 sleep 1
done

Example output:
 AMANDA: FILE 19971220 uri /root-sun4 lev 1 comp .gz program DUMP
 AMANDA: FILE 19971220 uri /misc lev 1 comp .gz program DUMP
 AMANDA: FILE 19971220 uri / lev 1 comp .gz program DUMP 

7. Restore the Amanda binaries and then exit restore. Use amrestore command as in Example 3.