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The RAL EISCAT computers

A basic description of our computer systems.

Computer Names

At the time of writing (March 2007) the core of the RAL EISCAT group's computing system is the "STP Cluster", a group of four powerful Tru64 unix machines clustered together so that their data processing power can be shared. This clustered computer system is linked to a large (0.7 Tb) data storage area, capable of accommodating a large amount of EISCAT raw data.

The clustered nodes are as follows

All of these machines share a common file system.

Because of computer security considerations, these machines are protected behind a firewall. However, users can access them by first logging into a machine outside the firewall and subsequently changing to one of the other machines.

Logging in to the RAL EISCAT Computers from outside RAL

Logging in from outside, one should use ssh to the generic address

c2.stp.rl.ac.uk

This will log the user on to one of the machines that are visible to the outside world. To enable X-windows traffic, use ssh as follows:

ssh +X c2.stp.rl.ac.uk

If you are accessing our machines from a desktop PC, you will need an SSH program. such as putty, to log into the machines a RAL. You can download a copy from the putty website [hint right-click and select "save target as"].

If you want to display X windows on your PC you will also need a running X windows emulator. In general you should talk to the computing helpdesk at your institute to see if they have one you can use. If you are very computer literate you can run a free X server, however far easier is MI/X costing $25 from microimages.com.

Once your X server is running, start putty and select "Connection/SSH/Tunnels" in the left hand window and select "Enable X11 forwarding". Then go back to "session" put c2.stp.rl.ac.uk in the "host name field" and select "ssh" as the protocol. The first time you run you should get a security alert and normally you just hit the "Yes" button.

This should enable you to access the front-door machine. To get from there onto one of the other nodes, one could use (for example) rlogin eiscatc or rlogin stp01 However, a better way of accessing the cluster is to give the command: rlogin c1

This will log you in to whichever of the clustered nodes is most appropriate, to ensure that the usage is spread out evenly around the various computers.

Disk Areas

It is not appropriate for this document to give a full list of the disk areas available on all the machines. However, here are some general points about the structure of our disk areas of which users should be aware.

Home areas

Users will generally have their home areas either on /home/{University}/ or on /home/eiscat/. For example, the home directory for an external user "fred" might therefore be /home/eiscat/fred.

To safeguard against loss of files, these areas are regularly backed up (incremental backups every night and a full backup each month).

Short Term Temporary Storage Areas

There are two types of temporary storage areas. The stager disks are large areas (approaching 1 TB in total) of temporary storage space, designed to hold raw data for a limited period only.

All users have the ability to create their own directories and files on the stager areas. However, in order to maintain enough space on the stager areas for new data to be staged in, any files on the stager areas that have not been accessed for 10 days will be automatically deleted. These areas are not backed up, so this is not the place to store your valuable programs, plots etc!

The largest stager area which is available for users to create their own sub-directories is:

If this area is full for any reason, users may also be able to create directories in:

Data staged in by users with get_mat and getLR actually goes into the top level of the /stager/y area, and is then soft linked to whichever directory has been specified by the user.

Longer Term Temporary Storage

In addition to the stager areas, a number of scratch areas are also available. These are called

/scratch/a to /scratch/h inclusive (at the time of writing /scratch/b, /scratch/d and /scratch/g are not publicly available).

The scratch areas are relatively large disk areas, on which all users have permission to create their own directories, and to write and delete files. The scratch areas are intended for temporary storage. Unlike the stager disks, however, there is no automatic deletion of files after a fixed time. The scratch areas should also be backed up nightly.

The scratch areas are intended for files that are too large to belong in a user's home area (e.g. analysed data files, data plots etc) and which need to be stored for longer than a few days. There is currently no limit to a user's allocation of scratch space. However, users are encouraged to review their scratch areas regularly and delete files that are genuinely no longer needed in order to keep space available for other users.

Software Areas

A number of directories exist which contain the publicly available multi-user software. Most of the main items of user software (e.g. get_mat, getLR, TAPECAT, intpipe, guisdap, Analysis, ncar utilities etc) can be found in the directory /soft/eiscat/share. Users should include this in their unix search path.

A number of useful matlab-based utilities, such as g2n, genLR and rtg can be found in sub-directories of /soft/eiscat/shlib/matlab. Users should include these in their matlab search path.

Other useful directories on the clustered machines are:

/soft/eiscat/guisdap, the sub-directories of which include the routines and experiment initiallisation files needed for the GUISDAP analysis program.

/soft/eiscat/etc/analysis, the sub-directories of which include the driver files and models needed for the RAL Analysis Program.

/soft/eiscat/etc/integrate, which contains a selection of integration definition files

For a practical example of how a user's search path and matlab path might be set up in practice, see the example path set-ups.

Created by ian
Last modified 2007-03-20 03:16 PM