This page describes the procedure for accessing and using our off-site backups. Only admins can do this -- if you want to get some file or directory back from the dead and are not an admin, please open a Bugzilla bug.

1. Managing Backups

1.1. Navigating the available backups

Using backup-manager:

backup-manager list
backup-manager list YYYY.MM.DD

1.2. Retrieving a backup

(NOTE: $VOLNAME is not simply username, it is <db|mail|user>.USERNAME)

Using backup-manager:

backup-manager get YYYY.MM.DD $VOLNAME.dump.gz.aescrypt

1.3. Restoring the volume dump to a volume with a new name

Using backup-manager:

backup-manager restore YYYY.MM.DD $VOLNAME.dump.gz.aescrypt $VOLNAME.restored

Manually:

cat /vicepa/hcoop-backups/restored/YYYY.MM.DD-$VOLNAME.dump.gz.aescrypt | \
  ccrypt -cdk /etc/backup-encryption-key | \
  gunzip | \
  vos restore deleuze /vicepa $VOLNAME.restored

1.4. Mounting the newly restored volume onto the filesystem

fs mkm /afs/hcoop.net/.old/tmp-mount $VOLNAME.restored
vos release old

1.5. Restoring a particular file

# examine /afs/hcoop.net/.old/tmp-mount

1.6. Unmounting the restored volume

fs rm /afs/hcoop.net/.old/tmp-mount
vos release old

1.7. Renaming the restored volume so it takes the place of the damaged/corrupted/erased volume

Do this if you want to restore an entire volume. This deletes the old volume and replaces it with the backup.

vos remove $VOLNAME
vos rename $VOLNAME.restored $VOLNAME

1.8. Removing the restored volume

If you only wanted to restore a few files from the volume, you should remove the local copy of the backup volume when done.

vos remove -id $VOLNAME.restored

2. Database Backups

cd /vicepa/hcoop-backups/restored
mkdir YYYY.MM.DD-db
cd YYYY.MM.DD-db
cat ../YYYY.MM.DD-databases.tar.gz.aescrypt | \
  ccrypt -cdk /etc/backup-encryption-key | \
  gunzip | \
  tar -xvzf -

3. Implementation

3.1. Requirements

• Encrypted backups
• Incremental backups
• Plays nicely with AFS

Thus, obnam. Things that might seem unobvious for anyone setting it up:

• afs backup volumes should be vos dumped (despite space waste locally) and backed up as a whole unit so that ACLs are preserved in the case of restoration

3.2. Configuration

There is an encrypted obnam repository at path on rsync.net. We are only using one repository for now, and only backing up afs.

Non-human user hcoopbackup has a gpg key and ssh key that allows it to access the obnam repository and rsync.net, respectively. Admins should generate individual gpg keys for accessing the backup.

The script /afs/hcoop.net/common/etc/scripts/hcoop-obnam-backup is run on an openafs file server machine from cron.daily as root (it must be a file server, since we use -localauth when dumping). The backup node has a keytab /etc/keytabs/hcoopbackup that allows the backup script to become the backup user.

First the entire system is backed up using vos backupsys. Then all backup volumes are dumped to /backups/hcoop-backups/dumps. Then the backup user takes over, and does an incremental backup to the remote repository at rsync.net.

On the first day of each week, make a full volume dump, afterward recording the time of the dump (or creation of the backup volume, whichever afs needs). On the following days of the week, make an incremental dump from the weekly full dump to the current date. Then, obnam can be used to access a dump for any given date and we only need to mount two dump files.

3.3. Future Plans

To make life simpler, individual machines would be backed up to afs volumes ({recovery|backup}.$machine.hcoop.net?). Probably as uncompressed tarballs, using an adaptation of the current system backup scripts to only copy files that cannot be restored automatically by setting the status file and running apt. Should each machine have a unique backup user (what happens if you have a $user/$host.hcoop.net key? Can it authenticate on all nodes via pam_krb5, or just on $host?)?

Databases could be backed up similarly, just by rsyncing over the /srv/databases directory. Same issues as previous backups with possibly bad file system state could arise however... if it's not impossible, we should do a proper database dump for each database separately. Perhaps we could "resurrect" $user.db, but instead of $user.dbbackup containing the last snapshot of the user's database dumps? Possibly not worth the effort / it might be better to keep them unexposed to the world at large (violation of database acls).

spamassassin should probably be writing its bayes database directly to afs anyway, so we can punt on that. There should not be any other local state.

In a world where every child gets a free pony for their tenth birthday, we could teach obnam about afs acls and just mount the $user.backup volumes (i.e. not double the local space requirements for volumes!) and backup from those with the intermediate dump. This would also allow users to control what data gets backed up via ACLs. However, reality bites.

CategorySystemAdministration CategoryNeedsWork