Hello, I am using IOR to write/read a shared file with up to 16 processes, each writing data of 128M in units of 256K. Here is the data I got with collective IO and independent IO.
# collective IO #procs write read 2 74.53 12.43 4 36.28 15.85 6 20.66 18.61 8 20.16 23.57 10 22.18 33.15 12 24.18 49.36 # independent IO to a single file # proc write read (MB/sec) 2 51.98 28.55 4 65.15 55.73 6 83.03 70.01 8 98.96 82.06 10 124.65 102.35 12 126.86 112.36 14 139.63 119.50 16 147.01 154.90 It is a little surprising to see collective IO performance is so low compared to independent IO. In addition, collective IO does not increase with increasing number of clients. The set servers has 5 IO servers can support at least 100MB/sec of IO rates directly from disks. Anybody can provide some hints? Thanks, Xinhua _______________________________________________ Pvfs2-users mailing list [email protected] http://www.beowulf-underground.org/mailman/listinfo/pvfs2-users
