Hi All.
Most likely a simple problem - but I'm obviously unable to solve it
When my processes NFS-write to the RAID, all processes are "blocked" (don't do anything) until the write operation is completed. The reason for "don't do anything" seems to be, that all NFS-read is stopped while the NFS-write is going on.
"iostat -nkx 1" looks like this:
Code:
Device:rkB_nor/s wkB_nor/s rkB_dir/s wkB_dir/s rkB_svr/s wkB_svr/s
pr2 10232.00 10234.50 0.00 0.00 16384.00 59935.75
pr2 57235.25 57223.15 0.00 0.00 60416.00 0.00
pr2 56915.50 56932.60 0.00 0.00 61440.00 0.00
pr2 67707.06 67702.07 0.00 0.00 54272.00 0.00
pr2 54517.38 54557.34 0.00 0.00 59392.00 0.00
pr2 54597.31 54557.34 0.00 0.00 62464.00 0.00
pr2 65770.36 65775.69 0.00 0.00 53734.65 0.00
pr2 54517.38 54514.49 0.00 0.00 61440.00 0.00
pr2 60912.38 60909.88 0.00 0.00 56320.00 0.00
pr2 54517.38 54557.34 0.00 0.00 61440.00 0.00
pr2 54597.31 54557.34 0.00 0.00 61440.00 0.00
pr2 36371.56 36371.56 0.00 0.00 26624.00 0.00
pr2 54517.38 54557.34 0.00 0.00 52224.00 0.00
pr2 54597.31 54557.34 0.00 0.00 53248.00 0.00
pr2 55716.44 55693.96 0.00 0.00 58368.00 0.00
pr2 59473.50 59533.45 0.00 0.00 60416.00 0.00
pr2 49149.69 49090.33 0.00 0.00 59817.82 0.00
pr2 54517.38 54557.34 0.00 0.00 38912.00 0.00
pr2 20304.12 20279.54 0.00 0.00 23552.00 71680.00
pr2 639.50 694.07 0.00 0.00 0.00 105611.52
pr2 0.00 0.00 0.00 0.00 0.00 114688.00
pr2 0.00 0.00 0.00 0.00 0.00 115712.00
pr2 0.00 0.00 0.00 0.00 0.00 114688.00
pr2 0.00 0.00 0.00 0.00 0.00 114688.00
pr2 0.00 0.00 0.00 0.00 0.00 115712.00
pr2 0.00 0.00 0.00 0.00 0.00 114688.00
pr2 949.75 885.45 0.00 0.00 0.00 108889.39
pr2 44844.94 44889.90 0.00 0.00 46080.00 757.18
pr2 60033.06 60048.05 0.00 0.00 56538.69 0.00
pr2 55816.36 55803.87 0.00 0.00 61440.00 0.00
pr2 72003.70 71991.21 0.00 0.00 48128.00 0.00
pr2 54597.31 54557.34 0.00 0.00 59520.54 0.00
pr2 54517.38 54557.34 0.00 0.00 61440.00 0.00
pr2 54597.31 54557.34 0.00 0.00 61440.00 0.00
pr2 56114.54 56131.86 0.00 0.00 60831.68 0.00
pr2 54677.25 54687.24 0.00 0.00 61440.00 0.00
pr2 58354.38 58374.36 0.00 0.00 61212.00 0.00
pr2 66667.88 66660.38 0.00 0.00 53248.00 0.00
pr2 54597.31 54557.34 0.00 0.00 61440.00 0.00
pr2 65483.80 65541.26 0.00 0.00 54272.00 0.00
pr2 55009.49 54997.00 0.00 0.00 60388.00 0.00
pr2 55529.08 55549.46 0.00 0.00 61440.00 0.00
pr2 60352.81 60327.44 0.00 0.00 57344.00 0.00
pr2 51879.44 51904.81 0.00 0.00 50176.00 14336.00
pr2 0.00 0.00 0.00 0.00 0.00 114566.34
pr2 1119.12 1088.76 0.00 0.00 0.00 104447.83
pr2 0.00 0.00 0.00 0.00 0.00 115712.00
pr2 0.00 0.00 0.00 0.00 0.00 114688.00
pr2 0.00 0.00 0.00 0.00 0.00 114688.00
pr2 0.00 0.00 0.00 0.00 0.00 115712.00
pr2 0.00 0.00 0.00 0.00 0.00 114688.00
pr2 0.00 0.00 0.00 0.00 0.00 114688.00
pr2 2717.88 2700.39 0.00 0.00 13312.00 52264.20
pr2 36371.56 36371.56 0.00 0.00 25600.00 0.00
pr2 25722.46 25727.41 0.00 0.00 21291.09 0.00
pr2 14948.31 14933.32 0.00 0.00 25600.00 0.00
pr2 20943.62 21008.57 0.00 0.00 19456.00 0.00
i.e. there is no read during write. I can set the length of the "write-only period" with the dirty_xxx parameters under /proc/sys/vm, but that does not really buy me anything.
Question: how can I convince the NFS-I/O to read and write at the same time? I am never writing to any file being read at the same time, so there is no risk in simultaneous read/write.
Thanks and Cheers
Bernd
