i have one question related to DCACHE client side. we do have a DCACHE server in hand and we access our ROOT files in our analysis.
The file TTrees are chained and the analysis is performed by looping over the total number of entries of this TChain. fine.
i wonder how the mechanism is working indeed. DCACHE implements a set of environment variables which allow to tune the client side. We were asked to use these settings:
now my question. How does it really work. does the ROOT client DCAP/DCACHE interface at each GetEntry() of the TChain, ping the server and download the DCACHE_RA_BUFFER ? or does it download the file itself? i mean are the requests to the server event based, or are these based on some more clever approach?
thanks in advance, and sorry if i missunderstand.
nm $ROOTSYS/lib/libDCache.so | grep dc_read