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

Richard Elling richard.elling at richardelling.com
Mon Jan 7 22:15:19 EST 2013


You might also look at zilstat, which is more interesting than the zpool iostat
output :-)

http://www.richardelling.com/Home/scripts-and-programs-1/zilstat
https://github.com/richardelling/tools/
 -- richard

On Jan 7, 2013, at 7:58 AM, steve at linuxsuite.org wrote:

> 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
> 
> 
> 
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--

Richard.Elling at RichardElling.com
+1-760-896-4422



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