Hi all,

I wanted to share details of a new, *fast*, filesystem that has been installed as network attached storage (NAS) local to the SEBASE Grid.

The filesystem is /n/sebase and is available from all nodes in the cluster using this name.  The intention is that this is a more convenient way to store files used or created by jobs running on the Grid than either your home directory (which may have limited quota), staffstore (which can be slow), or local directories on the nodes (which require additional work to share files and consolidate results).  The new filesystem has 1.4 TB of space and should be much faster than other network filesystems.

To use this filesystem, please contact support and ask for directory for yourself to be set up under /n/sebase.

Please note that while there is quite a lot of space on this filesystem you should be careful not to use up so much space it affects other users, and in particular should NOT use it for long term storage.  Instead, please use it only for active experiments where convenient and fast access to files is required.  Once your experiments have finished, please archive your files to more appropriate longer term storage, such as staffstore or a SVN repository.

The filesystem is configured as a (sort of) RAID 5, which will avoid data loss if one of its four disks fails.  For this reason, it is NOT backed up currently and this small risk of data loss is another reason why you should not leave files there long term.

Please let me know (as well as support) if you encounter any problems.  Also, there will be a short period of downtime at some point when the disks are moved physically closer to the Grid cluster (which may further improve performance) - I will negotiate this via this mailing list.

One thing to note: for security, this filesystem is only accessible directly from the Grid nodes.  To access it from other departmental (Linux) machines, you can mount it to a directory on that machine using sshfs:

- to mount: "sshfs head:/n/sebase/<username> <dir>" (replace <username> with your directory, and <dir> is an existing (empty) directory used as a mount point)
- to unmount: "fusermount -u <dir>"

(Note: If you create the mount directory in an NFS filesystem, such as your departmental home directory, then you may get an error "block devices not permitted on fs" when using fusermount if root does not have (explicit) execute permission on all directories in the path to the mount point.  You *could* add these execute permissions, but this might be a security risk; alternatively, use a mount directory on a non-NFS filesystem, such as /tmp.)

Thanks,

Simon


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GECCO 2011 SBSE Track
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Simon Poulding

Lecturer in Enterprise Systems
Department of Computer Science
University of York
Deramore Lane
York YO10 5GH

Tel: +44 (0)1904 325165
Fax: +44 (0)1904 325599

Email: smp@cs.york.ac.uk
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