Hi, I can't attend today but I send a status for GridKa below: > o FZK - Gregory > o status of setting up the xrootd system > o GPFS servers? * The GPFS fileservers are not yet ready and we have a setup with 12 nas boxes out of which 6 are actually used for providing collections which are beeing imported from SLAC. * I did some tests in order to compare the performance using xrd or nfs I am running 10 to 70 simultaneous jobs (I'm taking extra care that they start in the same time) in which I "KanCopyUtil -r -n 25000" one of the 42 test collections (chosen randomly) I have on disk on one of the nas box. I also took care that the running condition remain constant as much as possible (for expl: staying all along on the same batch worked). For each test, I am monitoring the network i/o flow and the time the jobs take by using the ganglia monitoring system. The results are summarized on the plot: http://www.slac.stanford.edu/~schott/internal/gridka/comparison_xrd-nfs.jpg When running through nfs, the net in is saturated and as a consequence the running time increases linearly with the number of jobs. When running through xrd, the net in is higher (the double when having 10 jobs) and still increase when I am running more jobs (it is 5 times more with 70 jobs). The running time is then shorter, for a given number of jobs running in parallel, when using xrd than when using nfs (the time ratio is 1/3 with 70 jobs); it also increases more slowly. * Pete suggested that I also perform a test in which I checked out specific packages in order to : > have a version of KanCopyUtil in which the TFile buffer cache > has been turned on. This _should_ cause ROOT to switch from making lots > of very small reads (4-5kB) to reading 512kB blocks. (Which may be a > bit large, but the exact size can be tuned later. I'm just curious if > this type of change has any effect on the performance you see.) The result are: | time net.in CPU ---------------------------------------------------- NFS (old tags) | 45 min 140 kB 10% XRD (ols tags) | 15 min 640 kB 35% ---------------------------------------------------- NFS (new tags) | 58 min 500 kB 10% XRD (new tags) | 6 min 600 kB 80% I added the system CPU as it varied by a large amount between these tests. xrd got faster with a higher CPU and a similar net.in while nfs got slower, with a higher net.in (similar to xrd) and the same CPU. Any comments are welcome! Cheers, Gregory