Filesystem data is gathered by the standard Cedar Backup collect
action. This data is placed into files of the form
*.tar. The first part of the name (before
“.tar”), represents the path to the directory. For
example, boot.tar would contain data from
/boot, and
var-lib-jspwiki.tar would contain data from
/var/lib/jspwiki. (As a special case, data from
the root directory would be placed in -.tar).
Remember that your tarfile might have a bzip2
(.bz2) or gzip (.gz)
extension, depending on what compression you specified in
configuration.
If you are using full backups every day, the latest backup data is always within the latest daily directory stored on your backup media or within your staging directory. If you have some or all of your directories configured to do incremental backups, then the first day of the week holds the full backups and the other days represent incremental differences relative to that first day of the week.
To do a full system restore, find the newest applicable full backup and extract it. If you have some incremental backups, extract them into the same place as the full backup, one by one starting from oldest to newest. (This way, if a file changed every day you will always get the latest one.)
All of the backed-up files are stored in the tar file in a relative fashion, so you can extract from the tar file either directly into the filesystem, or into a temporary location.
For example, to restore boot.tar.bz2 directly
into /boot, execute tar
from your root directory (/):
root:/# bzcat boot.tar.bz2 | tar xvf -
Of course, use zcat or just cat, depending on what kind of compression is in use.
If you want to extract boot.tar.gz into a
temporary location like /tmp/boot instead,
just change directories first. In this case, you'd execute the
tar command from within
/tmp instead of /.
root:/tmp# bzcat boot.tar.bz2 | tar xvf -
Again, use zcat or just cat as appropriate.
For more information, you might want to check out the manpage or GNU info documentation for the tar command.
Most users will need to do a partial restore much more frequently than a full restore. Perhaps you accidentally removed your home directory, or forgot to check in some version of a file before deleting it. Or, perhaps the person who packaged Apache for your system blew away your web server configuration on upgrade (it happens). The solution to these and other kinds of problems is a partial restore (assuming you've backed up the proper things).
The procedure is similar to a full restore. The specific steps depend on how much information you have about the file you are looking for. Where with a full restore, you can confidently extract the full backup followed by each of the incremental backups, this might not be what you want when doing a partial restore. You may need to take more care in finding the right version of a file — since the same file, if changed frequently, would appear in more than one backup.
Start by finding the backup media that contains the file you are looking for. If you rotate your backup media, and your last known “contact” with the file was a while ago, you may need to look on older media to find it. This may take some effort if you are not sure when the change you are trying to correct took place.
Once you have decided to look at a particular piece of backup media, find the correct peer (host), and look for the file in the full backup:
root:/tmp# bzcat boot.tar.bz2 | tar tvf - path/to/file
Of course, use zcat or just cat, depending on what kind of compression is in use.
The tvf tells tar to search for
the file in question and just list the results rather than
extracting the file. Note that the filename is relative (with no
starting /). Alternately, you can omit the
path/to/file and search through the output
using more or less
If you haven't found what you are looking for, work your way through the incremental files for the directory in question. One of them may also have the file if it changed during the course of the backup. Or, move to older or newer media and see if you can find the file there.
Once you have found your file, extract it using xvf:
root:/tmp# bzcat boot.tar.bz2 | tar xvf - path/to/file
Again, use zcat or just cat as appropriate.
Inspect the file and make sure it's what you're looking for. Again, you may need to move to older or newer media to find the exact version of your file.
For more information, you might want to check out the manpage or GNU info documentation for the tar command.