Backups

There follows a brief description of TCM's backup strategy. It contains no gold-plated guarantees against loss of data or service. Should you choose to backup your data onto several USB memory sticks to place under your pillow, and via the internet to various computers in different continents, I would regard it as healthy paranoia, not a vote of no confidence in TCM's computing infrastructure.

UNIX Home Directories

The main backup for these is accessible on all our Linux machines under the directory /backup. A backup is taken between about 2am and 5am each morning, placed in a directory named after the day of the week, and kept for a week. Sunday backups are retained for three weeks, and backups taken on the 1st of each month for several months. These backups are mounted read-only, so that you can browse them and copy your own files out of them at any time without asking for assistance.

In particular, if today is Wednesday and you have just deleted something, then

/backup/Wed/spqr1/thesis/all.tex

will be the copy of thesis/all.tex which the backup job saw in the early hours of the morning, assuming that your user ID is spqr1.

Risk Assessments

For those who wish to know the gory details, so they can work out how frightened to be, these are they.

Home Directories

Stored on four disks with RAID0+1 (concatenation + mirroring) in software. A cron job ought to report errors. Backed up to a software RAID6 array using rsync. The backup and original live in the same rack in the same room.

/rscratch

Hardware RAID6. A cron job ought to report errors, and the hardware does a full consistency check approximately once a week. No backup.

Applications

Stored on a software mirrored disk. A cron job ought to report errors. Manual backup to a machine in adjacent room occasionally.