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Group Space

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Informatics offers three types of disk space:

  1. Home directories.

    All DICE users have an AFS home directory with a reasonable amount of space in which to do their work.

  2. Personal homepages web space.

    All DICE users have some NFS space at /public/homepages/username/web/, at which they can create personal web pages at the URL

  3. Group space.

    These are created on demand for those people who need extra space to store data for a project they may be working on, or would like some shared area where several people can collaborate on the files held within the area. This space is typically AFS space.

This document concerns the last of these three, group space.

Group space

There are three main reasons to use group space:

  1. To store large amounts of data that's not appropriate to store in your home directory.
  2. A shared area where several people can collaborate on the files contained within that area.
  3. If you are working on something that may be worked on by someone else after you leave/move on to another project.
Typically group space will be made available in the filesystem on a path like: /afs/

Requesting group space

All requests for a new group space, or for more space to be allocated to an existing area, should be made via support. However there may be cost considerations depending on how much space you are looking for and whether you want backups of that space.

This table gives a rough idea of possible combinations and costs:

SizeCost+Mirror+Tape backup
Up to 200GB £0 +£0 +£0
500GB £250 +£250 +£250
Over 500GBis priced for each additional 500GB, as above.

These are one-off costs, not recurrent costs. For requests in size between 200GB and 500GB, the costs are variable and depend on things such as how long the space is needed and what it's needed for.

Things to bear in mind

  • By default space is provided on our redundant SAN storage in the Forum, so data should be safe from single disk or power supply failures.
  • Mirroring adds an extra nightly copy of your data to disks held at Kings Buildings, to protect against some disaster befalling the Forum server room.
  • Similarly daily tape backups are done at Kings Buildings, with daily backups being kept for 6 months, and monthly backups kept for 13 months. In the event of a disaster, restoring from tape will take longer.
  • Effectively any extra space bought lasts forever, or until such time as it is no longer required.
  • Staff involved in research are now entitled to 0.5Tb of storage on the central Datastore service. Half of this can be allocated to a group area on Datastore and further storage for these areas can be purchased though note that unlike the Informatics options, this will incur a yearly charge. For more details, see Data storage options
One point to be aware of, for large volumes of data that may change reasonably often, is that there is a trade-off in the way AFS space is allocated to that data. There is cache space that holds copies of data changes, and if data change is significant, then the space used may exceed the quota or filespace allocated. Some overhead is included when AFS space is allocated, but if your data is likely to change significantly over time, please mention this in the request, so that we can consider allocating a bigger overhead.

For truly huge space requests, e.g. 10s of terabytes, then it may make more sense for your project to buy its own SAN storage. Again contact support if this may apply to you.

See also Data storage options.

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