Setting up a namespace for SRM v2

On sites where the SRM v1 and v2 endpoints are front-ends for the same name service, data written by v1 remain accessible by v2 and vice versa. Data written by v1 can only have storage class hints expressed through the name space: the SE admin can map a particular directory to a particular storage class. To ease the transition from v1 to v2 VOs could design name spaces such that the different storage class instances only appearhigh up the hierarchy, so that there will be not so many.

Let us assume the following:

    RAW         --> T1D0
    DST         --> T1D0, but different tape set
    ESD_master  --> T1D1
    ESD_replica --> T0D1
    AOD         --> T0D1

Then the namespace SHOULD NOT be organized as follows:

    /my_exp/data/year/run/reco_pass/stream/RAW
    /my_exp/data/year/run/reco_pass/stream/DST
    /my_exp/data/year/run/reco_pass/stream/ESD_master
    /my_exp/data/year/run/reco_pass/stream/ESD_replica
    /my_exp/data/year/run/reco_pass/stream/AOD

The namespace SHOULD be organized as follows:

    /my_exp/data/RAW/year/run/reco_pass/stream
    /my_exp/data/DST/year/run/reco_pass/stream
    /my_exp/data/ESD_master/year/run/reco_pass/stream
    /my_exp/data/ESD_replica/year/run/reco_pass/stream
    /my_exp/data/AOD/year/run/reco_pass/stream 

If the namespace is organized as in the last example, it is easier to make the same data written with SRM v2 available again with SRM v1 respecting the Storage Class choices.

-- FlaviaDonno - 18 Apr 2007