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Hi Artem! Artem Trunov wrote: > Hi, all > > How does xrootd interact with underlying file system? Are there > tunable parameters? Like blocksize for i/o requests? I guess that those tweaks are to be found in the OS. Afaik in xrootd you can only tune the size of the subchunks in which a bigger block is to be split, but I believe that it's not used in your use cases. > When a client > sets readahead parameter, is it effectively a single disk read > operation? What about writing? In single tcp stream mode the client generally does not split blocks, so the server gets a ingle request, when you enable the multiple tcp sterams instead nearly all the blocks are splitted in various subchunks, so it's not. For writes xrdcp/XrdClient applies the same algorithm. > > Also xrdcp - the same questions - is it possible to tune disk i/o? > When writing to the local disk? No, it writes what the server sends in 4M/8M blocks, trying to make them sequential. The only parameters are those in the OS filesystem config. Fabrizio > cheers > Artem.