Backup Storage

We currently store our on-site backups across a couple drives on hal:

  • hal:/opt/backups (6 TiB usable; 2x 6-TiB Seagate drives in RAID 1 in an LVM volume group)

    This volume group provides /dev/vg-backups/backups-live which contains recent daily, weekly, and monthly backups, and /dev/vg-backups/backups-scratch, which is scratch space for holding compressed and encrypted backups which we then upload to off-site storage.

Off-Site Backups

Our main off-site backup location is Box. Students automatically get an "unlimited" plan, so it provides a nice and free location to store encrypted backups. We currently have a weekly cronjob that makes an encrypted backup using GPG keys and then uploads it to This takes about 20 hours combined to make and upload, and will probably take even longer in the future as backups grow. An email is sent out once the backup files are uploaded, and the link provided is shared with only OCF officers to make sure the backups are kept as secure as possible, since they contain all of the OCF's important data. The backups are already encrypted, but it doesn't hurt to add a little extra security to that.


Off-site backups older than six months (180 days) are permanently deleted by a daily cronjob.

Restoring Backups

The easiest way to restore from a backup is to look at how it is made and reverse it. If it is a directory specified in rsnapshot, then likely all that needs to be done is to take that directory from the backup and put it onto the server to restore onto. Some backups, such as mysql, ldap, and kerberos are more complicated, and need to be restored using mysqlimport or ldapadd for instance.


Onsite backups are pretty simple, all that needs to be done is to go to hal and find the backup to restore from in /opt/backups/live. All backups of recent data are found in either rsnapshot (for daily backups) or misc (for any incidents or one-off backups). Within rsnapshot, the backups are organized into directories dependings on how long ago the backup was made. To see when each backup was created just use ls -l to show the last modified time of each directory.


Offsite backups are more complicated because the backup files first need to be downloaded, stuck together into a single file, decrypted, extracted, and then put into LVM to get back the whole backup archive that would normally be found onsite. This essentially just means that the create-encrypted-backup script needs to be reversed to restore once the backup files are downloaded. Here are the general steps to take to restore from an offsite backup:

  1. Download all the backup pieces from This is generally easiest with a command line tool like cadaver, which can just use a mget * to download all the files (albeit sequentially). If more speed is needed, open multiple cadaver connections and download multiple groups of files at once.

  2. Put together all the backup pieces into a single file. This can be done by running cat <backup>.img.gz.gpg.part* > <backup>.img.gz.gpg.

  3. Decrypt the backup using gpg. This requires your key pair to be imported into gpg first using gpg --import public_key.gpg and gpg --allow-secret-key-import --import private_key.gpg, then you can decrypt the backup with gpg --output <backup>.img.gz --decrypt <backup>.img.gz.gpg. Be careful to keep your private key secure by setting good permissions on it so that nobody else can read it, and delete it after the backup is imported. The keys can be deleted with gpg --delete-secret-keys "<Name>" and gpg --delete-key "<Name>", where your name is whatever name it shows when you run gpg --list-keys.

  4. Extract the backup with gunzip <backup>.img.gz.

  5. Put the backup image into a LVM logical volume. First find the size that the volume should be by running ls -l <backup>.img, and copy the number of bytes that outputs. Then create the LV with sudo lvcreate -L <bytes>B -n <name> /dev/<volume group> where the volume group has enough space to store the entire backup (2+ TiB).

Backup Contents

Backups currently include:

  • Everything on NFS
    • User home and web directories
    • Cronjobs on supported servers (tsunami, supernova, biohazard, etc.)
  • MySQL databases (including user databases, stats, RT, print quotas, IRC data)
  • Everything on GitHub (probably very unnecessary)
  • LDAP and Kerberos data
  • A smattering of random files on random servers

Backup Procedures

Backups are currently made daily via a cronjob on hal which calls rsnapshot. The current settings are to retain 7 daily backups, 4 weekly backups, and 6 monthly backups, but we might adjust this as it takes more space or we get larger backup drives.

We use rsnapshot to make incremental backups. Typically, each new backup takes an additional ~3GiB of space (but this will vary based on how many files actually changed). A full backup is about ~2TiB of space and growing.

(The incremental file backups are only about ~300 MiB, but since mysqldump files can't be incrementally backed up, those take a whole ~2 GiB each time, so the total backup grows by ~3GiB each time. However, an old backup is discarded each time too, so it approximately breaks even.)

Ideas for backup improvements

  1. Automate backup testing, so have some system for periodically checking that backups can be restored from, whether they are offsite or onsite.