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Restoring deleted file(s)

We perform backups of user home directories and important system files to protect us against disasters and also to allow for recovery of files which have been accidentally deleted or damaged.

If you accidentally delete, damage or overwrite an important file, you have two options.

1. Restore the file(s) yourself

Note: This home directory backup is made three times a day starting at about hours 05, 13 and 21. Other backups of MATHS home directories do exist, so if you do not find what you need please contact help@maths.


From a MATHS Linux computer use this command (from the command line in a terminal):


or if you want a graphical display then:

  retrieve_backup -graphical

or you can change to the directory yourself, eg

cd $(readlink $HOME | sed -e 's=/mhome/=/mhome/backup-=g')

(unfortunately the location is not simple and does not follow the same pattern for all users).


The procedure from a MATHS windows machine needs to be verified.

2. Ask the Maths IT Help-Desk

Please send a mail message to help@maths (the departmental computing helpdesk) as soon as possible. The sooner you send a message the more likely it is that your file can be recovered.

In the mail message include:

  • the full name or names of the files you want back
  • the directory/folder-name the files were in
  • when the file was deleted or overwritten
  • when the file was last saved or written if you want an older copy of the file
  • when the files was first created

If you don't know any of these please say so and don't guess. If you know an approximate time (or a rough idea of the name) give us that but tell us it is an estimate.

Backups are not kept forever

The snapshot backups are done about once every 11-12 hours. They are only stored on disk (on this site but far away from the main fileserver) and can be used to recover files for several months although the time-spacing of the snapshots we keep gets longer after ~20 days.

Details of our backup retention policy

Full backups (of the latest snapshot) are written once a week to tape. The tapes are re-used after about 10 months. If you need any file which was deleted long ago we may not be able to recover it.

If you want the most up-to-date version of a file which was changed recently it will probably be in the snapshots. Since all versions may not be stored for very long we need to be told as soon as possible that you need it back.

I deleted a file which I edited today

We take one extra backup copy of the file in the morning (earlyish), one in the afternoon, one in the evening and one overnight. You may be lucky and we can retrieve your lost file, but you may not be.