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Backups and mirrors

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We backup and mirror all user home directories and most group space. We can also do the same for self-managed machines.

Mirrors

"Mirrors" are copies of data taken and stored on disk in an off-site location (not in the same part of town). Mirrors are normally made each night. They're quick to access but they only hold your data as it was yesterday (rather than, say, last week).

The Yesterday page explains how to access a mirror.

To make a mirror we use rsync to copy the data off, and AFS's "sites" feature to keep off-site copies of AFS volumes.

Backups

By "backups" we mean a copy of data made to tape. Again, this copy is off-site (King's Buildings) and we take them nightly. Tape is slower to copy and restore data than mirroring, but does have the advantage of keeping 6 months worth of daily backups, and 13 months of monthly backups. So you can go back in time to restore things as they were up to a year ago, but with increasing granularity. But after 13 months those tapes are recycled, so data older than that cannot be restored.

Read restoring files to find out how to have a file restored from a mirror or from a tape backup.

We use a commercial product, TiBS, to backup both machines and AFS data.

Self-managed backups

Users of self-managed machines can also use our backup server to backup a maximum of 5G of their data. See the self-managed backups topic for details.

Costs

If you have a large amount of data that you would like mirrored or backed up to tape, then the basic charge is £250 per 500GB for either a mirror or backup. So for us to mirror and backup 1TB of data, the cost to you would be:

2x£250 (mirror) + 2x£250 (backup) = £1000.

However, we will not charge for mirrors up to 200GB, nor for tape backup to 200GB.

Restoring files

If you have deleted a file from your home directory within the last 24 hours, you should find it in the directory called Yesterday within your home directory. The Yesterday directory is created nightly and is a copy of the contents of your home directory from the day before.

If you don't find the file you are looking for, contact support and tell us, as accurately as you can:

  • the names of the files
  • which directory they were in
  • roughly what date you want the files back from
We will then search the backup tapes for your files. This often takes a long time so please be patient - you may not get your files back on the day you ask for them.

Please try to backup important data and other items yourself in the first instance, so you do not need to rely on us. We cannot always guarantee full restoration of what you have lost.

Data stored locally on your DICE machine (e.g. in /disk/scratch) is NOT routinely backed up. It should therefore only be used for transient data or data that is easily reproducible.

Last reviewed: 
27/09/2016

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