ZFS and CPU usage



  • I have a Supermicro C3558 motherboard which is 4 threads @2.2GHz. The system has a two consumer SSD's. I installed Pfsense on one of the SSDs and the load average was "0.81, 0.69, 0.54" with CPU hovering about 11%.

    I wiped this setup and reinstalled the same config on ZFS with mirrored SSDs. The load average moved upto "1.04, 0.96,0.92" with CPU hovering around 20%.

    ZFS is using double to CPU with the same configuration. Is this expected?

    Packages I have installed are SNORT, PfblockerNG and Status_Traffic_Totals.


    I also did a test without any packages, with ZFS load average was "0.65, 0.62, 0.52" and CPU was about 11%. Disk bandwidth is like,

    zpool iostat 5
                   capacity     operations    bandwidth
    pool        alloc   free   read  write   read  write
    ----------  -----  -----  -----  -----  -----  -----
    zroot        511M   117G      0     41  23.3K   193K
    zroot        511M   117G      0     38      0   174K
    zroot        511M   117G      0     38      0   173K
    zroot        511M   117G      0     41      0   190K
    zroot        511M   117G      0     39      0   176K
    zroot        511M   117G      0     39      0   180K
    zroot        511M   117G      0     39      0   178K
    zroot        511M   117G      0     40      0   182K
    zroot        511M   117G      0     38      0   175K
    zroot        511M   117G      0     39      0   179K
    zroot        511M   117G      0     50      0   220K
    zroot        511M   117G      0     39      0   180K