SE-posix SAM test

Everyone should be aware of the fact that a new SAM test will soon be introduced that will test the posix-like access to your site SE from our WNs. The test uses lcg-cr first copy a file to the SE, then uses GFAL (the Grid File Access Library) to perform the open(), read() and close() of the file. GFAL does all of the translation between the LFN (Logical File Name) and the TURL that will be used to access the file. It supports rfio, (gsi)dcap and gridftp so it does not matter if your site has a dCache, DPM or CASTOR. The file is removed after the test via an lcg-del.

It is essential to test this property of the SEs since it is an expected access pattern for the VOs when they are running analysis jobs at sites. In many cases it is more efficient to use the posix-like access rather than copying the entire file (or files) to the WN before processing starts.

In the first instance this new test will be NON-CRITICAL, so sites should not worry if they are not passing. We will use the information gathered from the test to solve site-specific issues. Once things become more stable it is likely that this test will move into the existing replica management super-test.