4. Files and Filestores

Home Directories

The home filestore is the most important of all file systems. This is where the system places you when you initially log in. It is located on the SAN and is where you will carry out most of your work. This area is backed up. For further information please see www.csar.cfs.ac.uk/user_information/san/san_home.shtml

Local Temporary Filesystems (/tmp)

As is traditional on UNIX machines you can use /tmp for temporary filespace. A secondary directory exists for the duration of jobs located in /tmp which is called $TMPDIR. There is no backup performed on this area and files are purged regularly. Note that $TMPDIR is cleared automatically when the job terminates. For more information on the usage of this filesystem please see www.csar.cfs.ac.uk/user_information/san/san_local_tmp.shtml

The Global Temporary Filesytem (/santmp)

Home directories are often insufficient for running batch jobs. The global temporary filesystem known as santmp provides a cheap resource for storing files that may be required over multiple batch jobs. $SANTMP can be used as a synonym for your santmp directory. No back up of this area is performed. Please see www.csar.cfs.ac.uk/user_information/san/san_tmp.shtml for more information and suggested usage.

Hold/Long Term Storage

The hold directory is an offline tape storage device but data is served by a filesystem on the SAN. Most data will be offline, when requested data is migrated to the online disk storage and is held in a dual state. Data when placed in hold will migrate to the tape system at a later date. To use this area you require a suballocation of resource from your PI and they can increase this as necessary. There is no backup on these directories. The number of files you can store here is typically limited to 300 and the smallest file you should store here is 40MB.

The command to fetch data from the tape system is dmget. The status of files can be interogated with dmls -l. Users are expected to pre-fetch files required for batch jobs or analysis. Detailed advice on usage can be found at www.csar.cfs.ac.uk/user_information/san/san_files_hold.shtml

Data Transfer to and from CSAR Machines

There are a number of ways to transfer data to/from the machines:

• scp (preferred)
• sftp
• rcp
• tape

Please see www.csar.cfs.ac.uk/user_information/san/san_files_copy.shtml for more help.

Other information

• Other filesystem options www.csar.cfs.ac.uk/user_information/san/san_other.shtml
• I/O and SAN performance www.csar.cfs.ac.uk/user_information/san/san_files_performance.shtml