19 September 2012


We had an interesting experience with the CASTOR upgrade to 2.1.12, that the link between the storage area (SA) and the tape pool disappeared in the upgrade. In GLUE speak, the SA is a storage space of sorts, which may be shared between collaborators - we use it to publish dynamic usage data.

In CASTOR, we have used the "service class" as the SA; there is then a many-to-many link to disk pools and tape pools, something like this:

The dynamic data of each pool then gets shared accordingly between all the SvcClasses, which is (was) the Right Thing™.  Now the second association link has gone away, we're wondering how to keep publishing data correctly in the short term - and the upgrade got postponed by a week amidst much scratching of heads.

The information provider may just have enough information (in its config files) to restore the link, but it'd be a bit hairy to code - we're still working on that - but it may just be better to rething what the SA should be (which we will). We also tried a supermassive query which examined disk copies of files from tape pools to see which disk pools they were on, and then linking those with service classes - which was quite enlightening as we discovered those disk copies were all over the place, not just where they were supposed to be...

In the interest of getting it working, we decided to just remember and adjust which data publishes where - meanwhile, we shall then rethink what the SA should be in the future.

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