Computing Service

Archiving, backups and file transfer

All users who store data, programs etc. on any sort of computer system need to give thought to the provision of backup copies; further advice is below. You may also have important stored material which ought to be archived in some permanent form; the DSpace digital repository is one way to achieve this.

For backup or archiving, or for many other reasons, you may need to transfer files from one computer system to another; the file transfer pages give advice on ways to do this where Computing Service systems are involved.

Backup strategies and technologies

It still happens that people lose an entire thesis or book because, for instance, they have relied on a single copy on a hard disk which ceases to work. You should always aim to keep a second copy of work in progress (not on the same disk), not out of date by more than a few hours' worth of work. In case of disaster, a reasonably up-to-date paper copy is better than nothing; it may be possible, though laborious, to reconstruct the document by scanning.

Backup is the end-user's responsibility; many communal systems have some central provision for backup, but you need to judge whether this is adequate for your needs. If you are storing material on your own equipment then backup is entirely your responsibility.

You may have valuable data, email or programs on a system of your own on your desk, or it may be stored on a system belonging to the Computing Service or a College or Departmental network.

Computing Service systems

On the PWF, backup copies of the file servers holding users' personal filespaces are taken at intervals, for use in case of major hardware failures. However, these are not kept for an extended period, and it is difficult in general to arrange to retrieve an individual user's files (sometimes PWF files can be recovered using the technique described at http://www.cam.ac.uk/cs/docs/faq/q2.html, but this will not work in all cases). Normally you should make adequate backup copies on USB devices, CDs, DVDs or ZIP disks (there are writable CD drives on most PWF machines, ZIP drives on a few and USB connections on all). If your main copy of important data is kept on removable media (USB, CD, etc.), it is advisable to keep two current copies as well as routine backup copies.

Do not store data on the local hard disks (e.g. on drive C: on a Windows PC) or the desktop on the PWF, as such data cannot be guaranteed to remain available from session to session, even on the same computer. Data that you wish to keep should be stored in your PWF personal filespace (drive U: on Windows), and backed up as described above.

The Hermes message store has disaster recovery backups similar to the PWF servers - that is, they are for system recovery only. Hermes also keeps copies of deleted email for limited periods of time so that in most cases we can restore a user's accidentally deleted email. We recommend that users keep their own offline backups of their email, especially if they want to archive large volumes of it.

Other networked systems

If you keep files on a fileserver in your College or Department, you should ask your local computer support staff what backup arrangements are made; they will normally have provision for recovery from major disk failures, for instance, but they may not easily be able to retrieve individual files.

If you have your own equipment

This section applies to any equipment for which you are responsible, but is particularly vital for owners of laptops. Every year there are instances of stolen laptops which contain the only copy of someone's thesis, essential papers or laboriously collected data.

You should always keep an up-to-date copy or copies of any important data on USB devices, CDs, DVDs or ZIP disks, stored separately (i.e. not being carried about in a laptop case). "Important", in this context, means anything that you would find difficult or tedious to reconstruct - e.g. taking more than an hour or two at most. It may also be convenient to keep backup copies of important documents on the PWF; your PWF filespace can be mounted on your desktop using the pilot CIFS service (or MacAFP for Macs), which makes it very easy to copy files across.

You may also want to consider whether the time invested in the software setup and configuration of your computer is such that the whole system ought to be backed up to a mass storage medium such as CD, DVD, tape, secondary hard drive etc. The cost of rebuilding your system after a major crash (or setting up a new system after yours has been stolen) may be very considerable for you or your local Computer Officer or both. The Computing Service can provide advice on backup devices and strategy where local facilities or advice do not exist.

Users with valuable files (or valuable backups) stored on disks of unusual format or non-standard devices may like to consult the Computing Service data transcription service (contact Reception) to discuss making copies on more standard media.

The title of this document is: Archiving, backups and file transfer
URL: http://www.cam.ac.uk/cs/arch/

Last updated: February 2009

Useful Links

Back-up & File Management Documentation