NFS to AFS group space move.

Our server "hippocampus" will be switched off in August, and we're presently in the process of moving the shared areas it holds to AFS file space. This document is intended to highlight some questions people have regarding the differences and advantages of AFS, and so make the transition easier. If you are unfamiliar with AFS, take a look at http://www.inf.ed.ac.uk/systems/AFS or the top 10 questions http://www.inf.ed.ac.uk/systems/AFS/topten.html.

We’re contacting you as a first pass in arranging the move of your shared area/s. Hopefully there will be so little change that not everyone in the group will need to know that the move is taking place. Take a look through this document, and let us know if any of the changes would warrant contacting the whole group.
If there is anything else that we should know about before the move please let us know.

Procedure

The plan is to create the AFS space, rsync the data from the old area to the new AFS area, then (at a prearranged time) rename the old area so it becomes inaccessible, whist pointing the old paths to the new space. Hopefully this will go extremely smoothly and no one will notice they are now working from AFS space!

Old Data

If the data isn’t needed any more please lets us know, this is a good opportunity to tidy up and save space. In some cases the area is so small that the best course of action would be to take a copy yourself and save it in your homedir, or burn it to DVD.
We can archive the data to tape or just delete it, just let us know what you’d prefer.

Path
After the move to AFS, if the space was under the /group structure, the group will still be available via the same path as before e.g /group/project/<groupname> will still be accessible via that path, but will also be available via the AFS path /afs/inf.ed.ac.uk/group/project/<groupname>
This /afs path is a global path, and so will work anywhere you have AFS access.
Groups that weren't already under /group can be put there if requested.

Webpages
We need to know if the group space contains web pages. Access permissions need to be tweaked so that the pages will work with AFS (explained here http://www.inf.ed.ac.uk/systems/AFS/topten.html#web)

Group Access

Access to the group is controlled by ACLs, as described here http://www.openafs.org/pages/doc/UserGuide/auusg007.htm#HDRWQ46

This is a good opportunity to remove people from the group that should no longer be members.
If there is an existing unix group, the AFS equivalent automatically contains the same members, but is called inf:<groupname>. You can view the current membership of the group with the command getent group <groupname>. Let us know if anyone should be removed from the group.

Please let us know what level of access the group members require.

If there isn't already a group, we can create one in the format afs-<groupname>.

ssh keys/unison
http://www.inf.ed.ac.uk/systems/AFS/topten.html#sshkey

http://www.inf.ed.ac.uk/systems/AFS/topten.html#unison

Long Jobs
AFS tokens expire after 18 hours, you need to notify support if you need to run jobs that run longer than this.

Yesterday

There is a directory within the group area called Yesterday, this contains a copy of the group area as it was on the previous day.

Advantages
AFS makes it easier to give machines which are not part of the DICE infrastructure full and secure access to our filesystem. AFS clients are available for Linux, Solaris and Windows.

AFS simplifies disk management. Under AFS, partitions can change location while still being fully available to users. In addition, AFS includes sophisticated tools for monitoring and controlling disk and server usage.

AFS gives us a more robust file service. When an AFS server goes down, the user will only notice if they try to write to a file on the faulty server or read a file which is not in the local cache. For additional reliability, read-only data can be replicated across several servers for additional performance or availability. This feature replaces many of the ad-hoc mechanisms currently in place. In particular, the Yesterday system can be automated as part of the AFS backup process.

AFS allows us to share files and data with institutions throughout the world who also use AFS in a secure manner and should simplify collaboration. Local users benefit from improved access to their data while traveling.

-- RossArmstrong - 01 Jul 2009

Topic revision: r1 - 01 Jul 2009 - 14:29:56 - RossArmstrong
 
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