Moving Users to AFS Home Directories

The AFS filesystem project is now at a stage where we wish to start moving the home directories of large numbers of existing Informatics users to AFS file space. We are already putting all new non-student home directories in AFS file space and from the start of the 2007 - 2008 academic year, all new users will receive AFS home directories. It is important that we get we get as large a number of people using AFS home directories as quickly as possible in order to identify any issues, particularly load related, before the start of the next academic year.

The following principles apply for the move:

  • All users with the staff role will have their existing NFS home directories replaced by AFS home directories. Current students and visitors will retain their NFS home directories until they leave the school or their role changes.

  • Moves will be done on a per-partition basis. All eligible users on a partition will move to AFS at the same time (but see exceptions below). As far as possible, a partition will be decommissioned and recycled after its users have moved to AFS.

  • Users who are retaining their NFS home directories will be consolidated into large NFS partitions. The opportunity will be taken to ensure that a given partition (NFS or AFS) contained either user or group data but not both.

  • the first users moved will be those whose home directories are located on the D2 SCSI JBODs attached to phoenix, roc and pegasus. This will allow us to rectify an inequality whereby most home directories reside on RAID 5 arrays but a few are locate on single SCSI disks.

  • All AFS users will get an initial home directory quota of 5GB or their existing home directory quota, whichever is the greater. Until the proposed monitoring system is available, AFS partitions will not be overloaded.

  • When moving a user to AFS, the user's AFS home volume will be created and the entire contents of the user's existing home directory will be copied to the new AFS home directory. There will be a settling in period of the order of two weeks or so during which the users NFS home directory will remain accessible and during which support will be given to those users whose use of the file system meets certain criteria (see exceptions below). Once this settling in period is over for all AFS users on a partition and the remaining NFS data has been moved elsewhere, the partition will be recycled. This has the disadvantage that unwanted data may be copied cross to AFS but it is felt to be preferable that the old NFS partitions can be recycled in an organised manner.

Timetable

  • An initial email message will be circulated to all non-student users before the end of March announcing the move to AFS home directories

  • Two weeks before they are due to move, users will receive a second email explaining the process in more detail and containing criteria for system use which an AFS home directory may have an impact on. Users whose system usage match these criteria will be asked to contact the afs project team as quickly as possible. If a solution of the user's needs cannot be found in the short term, their move to AFS will be delayed until such time as a solution is available. Where a solution does exist, users will be given any support required. We hope to be able to move the first set of users by the middle of April.

Exclusions

Currently users will be unable to move to AFS if:

  • They are Condor users
  • Their public_html directory is accessed by a web server
  • They run long term jobs (longer than the life of an AFS token) on multiple machines.

They will be able to move but will need support with the move if they:

  • Run long term jobs on a single on or a few machines
  • Have changed the default permissions of their home directory
  • Run user cronjobs
  • use secure shell public keys

As the solutions to this second set of problems become more standardised, they will become less of an issue

-- CraigStrachan - 22 Mar 2007

Topic attachments
I Attachment Action Size Date Who Comment
txttext afs-detailed-letter.text manage 1.1 K 05 Apr 2007 - 13:53 CraigStrachan  
txttext afs-general-letter.text manage 1.5 K 05 Apr 2007 - 13:51 CraigStrachan  
Topic revision: r6 - 12 Apr 2007 - 13:57:18 - ChrisCooke
 
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