Tuning NFSD Server Daemon for Performance


Do note that NFSD Daemon play an important component in performance tuning. Here are some tips

  1. Number of Instances of the NFSD Server Daemon. By default, the instances of NFSD = 8. From Optimizing NFS Performance, the author recommend  that system admin should use at the very least one daemon per processor, but four to eight per processor may be a better rule of thumb. To modify the number of nfsd, you can edit the RPCNFSDCOUNT at the NFS startup script (/etc/rc.d/init.d/nfs on RHEL, Fedora or CentOS)
  2. If you want to determine the nfsd yourself, you can look at the NFS statistics in details which are provided by the Linux kernel at /proc/net/rpc/nfsd
  3. A sample of /proc/net/rpc/nfsd

    rc 0 47750055 170015423
    fh 39 0 0 0 0
    io 376475178 3831903891
    th 8 18573687 48505.610 3718.131 2831.176 0.000 1813.483 1468.532 1399.593 1551.349 0.000 12224.473
    ra 16 122635704 971110 83992 77018 15770 11434 1655 550 882 407 518440
    net 217768755 0 217768891 1072
    rpc 217765688 0 0 0 0
    proc2 18 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
    proc3 22 3 24906977 238795 7255551 10595346 837 124313278 42671631 2419345 5043 5865 0 2399297 5130 2560 1593 48707 133600 34910 3 0 2650721
    proc4 2 0 0


  4. To analyse some of the output parameters, I’ll be drawing most of the information below from an excellent article “Understanding Linux nfsd statistics”. A brief summary is as followed:
    rc reports the stats for the NFS reach cache. The three numbers are cache hits, cache misses, and”nocache” which is presumably requests that bypassed the cache.
    io reports the overall I/O counter. The 2 numbers are bytes read, bytes written
    th reports the nfsd thread utilization. The first number is the numberof nsfd thread configured. The second number of times any thread is used. The remaining ten numbers are histogram representing a 10% range of thread utilisation in seconds
    ra reports the read-ahead cache. The first number is the  read-ahead cache size. The next 10 numbers are the number of times an entry was found in the read-ahead cache < 10%, < 20%, …, < 100% in to the cache. The last number on this line is the number of times an entry was not found in the cache.
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