03 April 2007

dCache-NGDF workshop

Colin Morey and myself attended the dCache-NGDF workshop last week in Copenhagen (hence the little mermaid). The dCache developers presented lots of useful information. The presentations can all be found here.

NGDF are committing effort to dCache development as they plan to use dCache to create a distributed Tier-1 with the "head" nodes based in Copenhagen (where the network fibres come in) and gridftp doors and pool nodes spread across mulitple sites in Scandinavia. It looks to be quite an ambitious project, but they have already started making changes to the dCache GridFTP code in order to get round the problem of a file transfer first getting routed through a door node before ending up on the destination pool. This might be OK within a site, but it becomes more of a problem when the transfer is over the WAN. Another solution to this problem involves adopting the GridFTP v2 protocol (which has not yet been adopted by Globus). It appears that both approaches will be developed.

Another interesting bit of news regards new releases of dCache. All of the SRM 2.2 stuff that is required by WLCG will come with v1.8 (sometime this month). At the same time, v1.7.1 will be released which will contain all of the same code as v1.8
other than the SRM 2.2 stuff. It would appear that they want to retain a "stable" version of dCache at all times, in addition to a version that is required by sites supporting WLCG VOs. While sensible, it doesn't inspire huge confidence in the SRM 2.2 code. In summary, all of the GridPP sites will have to upgrade to v1.8.

One last thing about 1.8 is that although it will support all of the SRM 2.2 concepts such as space reservation and storage classes (T0D1), it will not come with a suitable generic information provider (GIP) to publish this information to the BDII. GridPP may have to lend some effort in order to get this fixed.

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