[OmniOS-discuss] No I/O on ZIL logs?

[steve at linuxsuite.org]

Howdy!

       I am doing some testing of zfs on OmniOS. It seems that the ZIL logs
never get any I/O.  I have a zpool as follows

root at live-dfs-1:~# zpool status data1
  pool: data1
 state: ONLINE
  scan: resilvered 937G in 17h53m with 0 errors on Sat Jan  5 08:52:32 2013
config:

        NAME                         STATE     READ WRITE CKSUM
        data1                        ONLINE       0     0     0
          raidz2-0                   ONLINE       0     0     0
            c5t5000C500525BFB31d0s0  ONLINE       0     0     0
            c5t5000C500525C2F91d0s0  ONLINE       0     0     0
            c5t5000C500525C72B1d0s0  ONLINE       0     0     0
            c5t5000C500525C9673d0s0  ONLINE       0     0     0
            c5t5000C500489956C1d0s0  ONLINE       0     0     0
            c5t5000C500525EB2B9d0s0  ONLINE       0     0     0
            c5t5000C500525F2297d0s0  ONLINE       0     0     0
            c5t5000C50045561CEAd0s0  ONLINE       0     0     0
            c5t5000C50048990BE6d0s0  ONLINE       0     0     0
            c5t5000C500489947A8d0s0  ONLINE       0     0     0
        logs
          mirror-1                   ONLINE       0     0     0
            c1t2d0                   ONLINE       0     0     0
            c1t4d0                   ONLINE       0     0     0
        cache
          c1t5d0                     ONLINE       0     0     0

errors: No known data errors

      Then I simply have a script that does some writing to the zpool.

     If I run

    zpool iostat -v data1 5

   I get output like this ( see below). Why is there never any I/O to the
 logs? I understood that these logs would be written first before
 the data is commited to the zpool. I can't find any evidence that this is
happening. Lights on hardware don't blink either to indicate activity. I
have verified that the disks used for the ZIL are writable.
 Why is this not happening? How can I make it so?

      thanx - steve

 root at live-dfs-1:~# zpool iostat -v data1 5

                                capacity     operations    bandwidth
pool                         alloc   free   read  write   read  write
---------------------------  -----  -----  -----  -----  -----  -----
data1                        9.98T  16.8T      0  3.14K      0   113M
  raidz2                     9.98T  16.8T      0  3.14K      0   113M
    c5t5000C500525BFB31d0s0      -      -      0    146      0  16.6M
    c5t5000C500525C2F91d0s0      -      -      0    147      0  16.6M
    c5t5000C500525C72B1d0s0      -      -      0    146      0  16.6M
    c5t5000C500525C9673d0s0      -      -      0    147      0  16.6M
    c5t5000C500489956C1d0s0      -      -      0    146      0  16.6M
    c5t5000C500525EB2B9d0s0      -      -      0    146      0  16.6M
    c5t5000C500525F2297d0s0      -      -      0    146      0  16.6M
    c5t5000C50045561CEAd0s0      -      -      0    146      0  16.6M
    c5t5000C50048990BE6d0s0      -      -      0    146      0  16.6M
    c5t5000C500489947A8d0s0      -      -      0    146      0  16.6M
logs                             -      -      -      -      -      -
  mirror                         0   148G      0      0      0      0
    c1t2d0                       -      -      0      0      0      0
    c1t4d0                       -      -      0      0      0      0
cache                            -      -      -      -      -      -
  c1t5d0                      111G  7.51M      0    179      0  18.6M
---------------------------  -----  -----  -----  -----  -----  -----


                                capacity     operations    bandwidth
pool                         alloc   free   read  write   read  write
---------------------------  -----  -----  -----  -----  -----  -----
data1                        9.99T  16.8T      1  3.56K  10.3K   105M
  raidz2                     9.99T  16.8T      1  3.56K  10.3K   105M
    c5t5000C500525BFB31d0s0      -      -      0    158  1.58K  15.9M
    c5t5000C500525C2F91d0s0      -      -      0    168  2.38K  15.9M
    c5t5000C500525C72B1d0s0      -      -      0    163  2.38K  15.9M
    c5t5000C500525C9673d0s0      -      -      0    154    810  15.9M
    c5t5000C500489956C1d0s0      -      -      0    163  1.58K  15.9M
    c5t5000C500525EB2B9d0s0      -      -      0    161  1.58K  15.9M
    c5t5000C500525F2297d0s0      -      -      0    158      0  15.9M
    c5t5000C50045561CEAd0s0      -      -      0    165      0  15.9M
    c5t5000C50048990BE6d0s0      -      -      0    149      0  15.9M
    c5t5000C500489947A8d0s0      -      -      0    153      0  15.9M
logs                             -      -      -      -      -      -
  mirror                         0   148G      0      0      0      0
    c1t2d0                       -      -      0      0      0      0
    c1t4d0                       -      -      0      0      0      0
cache                            -      -      -      -      -      -
  c1t5d0                      111G     8M      1    260  1.38K  26.0M