PETAL: 1.3 Filesystem and Directories

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Directories for new allocations should be setup on the petal-fs-01 server which provides the interface between the client machines and the tape system.

The server has a 25TB cache (16 x 1.6TB disks in a RAID6 array) which is mounted on /export/cache. The initial configuration has 2 volumes using this cache - spectra2 which has 20TB, and spectra1 which has 5TBs.

We don't expect any new volumes to be added. If more tape drives are purchased, then it would be possible to add more volumes - but with 4 tape drives, probably 2 volumes is about the maximum. (If, for example, there are 2 volumes, each of which is trying to keep 2 tape copies of the data - it can take up to 12 hours to copy a full tape - you could have all 4 drives being used just to take the second copies - the system will then try swapping tapes in and out of drives to give several processes tape time - it then gets very slow).

Most filesystems will be added under spectra2 to ensure that 2 copies of the data are kept, and that a large cache is available. The other (spectra1) volume can be used when there's a clear understanding that only 1 copy of the data will be retained - not to be used under normal circumstances. Details of how volumes and caches are created are in section 3.2.

Steps to create a new filesystem for a new user (as root on petal-fs-01):

  • cd /export/archive/spectra2
  • mmparam -g0 spectra2 (temporarily switch off grace period)
  • mkdir project1
  • chown PI_user_name:513 project1
  • chmod 700 project1
  • setfacl -m u:root:rwx project1
  • setfacl -m u:USER1:rwx project1
  • repeat above command for all users who require read/write access
  • setfacl -m u:USER2:rx project1
  • repeat above command for all users who require read-only access
  • mmparam -g1h spectra2

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T950

Topic revision: r4 - 17 Nov 2017 - StuartBorthwick1
 
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