Department of Computing Imperial College London
Online file retrieval

We have an online backup system from which you can recover earlier versions of any files you may have lost or corrupted.

To recover files from Linux

cd /vol/recover/homes/username
The full copy of your home directory as of the previous night is in the sub-directory full. Each of the inc-NN sub-directories contain files that changed about NN nights ago.

That is:

full/     - last night's copy of your home directory
inc-00/   - files that changed between last night and 2 nights ago
inc-01/   - files that changed between 2 nights ago and 3 nights ago
inc-02/   - files that changed between 3 nights ago and 4 nights ago
inc-12/   - files that changed between 13 nights ago and 14 nights ago
Group project directories are also backed up and can be found in:

Remember if you copy any files from the backups to your current home directory you need to rename them to avoid overwriting existing files!

In the specific case of your .email file - your email Inbox - you need to be especially careful so as not to lose recent email. We recommend that you copy (say) last night's version back as follows:

cp /vol/recover/homes/USERNAME/full/.email ~/IMAP/RecoveredInbox

Now you can use your favourite email client (perhaps after refreshing it's idea of what IMAP folders exist), to select the RecoveredInbox folder, view the messages, and decide which messages to move back into your main Inbox. We recommend that you end up deleting the RecoveredInbox folder - it's only a transitional folder, don't keep it hanging around for ever!

Accessing Online Backups from Windows

Start -> Run...  \\\homebackup
Start -> Run...  \\\volbackup
The folder "homebackup" will contain backups for your home directory. The folder "volbackup" will contain backups of the /vol areas such as the group project areas. Version details the same as mentioned above for Linux.

The Online backup process in a bit more detail

Every night, every home directory (and other important area) is examined and all changed files and directories are detected. The last incremental directory - currently inc-12 - is deleted, and all the inc-NN directories are renamed as the next one on, forming a shift register - inc-11 is renamed as inc-12, inc-10 as inc-11 and so on right back to inc-00 as inc-01. A new empty inc-00 directory is created.

Then, foreach changed file, the previous copy is moved from full/FILENAME to inc-00/FILENAME (directories are created as needed), and the new copy is then copied from your home directory into the full directory.

In fact, we have two identical services, the original system located in Huxley, and to provide greater data resilience should a disaster occur in the Huxley computer room, one located in the College (ICT) machine room on the other side of campus.

The service based in Huxley may be accessed directly by changing /vol/recover/ to /vol/recover1/ in the above examples, or \\\homebackup1 or \\\volbackup1 for Windows users.

The service based in the ICT machine room may be accessed directly by changing /vol/recover/ to /vol/recover2/ in the above examples, or \\\homebackup2 or \\\volbackup2 for Windows users.

/vol/recover/ and \\\homebackup and \\\volbackup will point to whichever of the services we are recommending, and may change from day to day.

© CSG / Oct 2006