l2_io_error and l2_cksum_bad are not null and growing

[Andriy Gapon]

On 20/10/2014 20:32, Alex wrote:
> Hello.
> 
> We seem to have a problem with l2arc on zfs system on 10.1-BETA1 FreeBSD
> 10.1-BETA1 #1 r271710 server. The server has a l2arc cache configured from Intel
> SSD 480G disk. The problem is that l2_io_error and l2_cksum_bad values are
> constantly growing, however there are no traces of any hardware malfunctioning.
> As for now, the values are
> kstat.zfs.misc.arcstats.l2_io_error: 1501
> kstat.zfs.misc.arcstats.l2_cksum_bad: 19480

Please see if the following patch might help
https://github.com/avg-I/freebsd/compare/review/l2arc-write-target-size.diff

> Here is the output of zpool status:
>   pool: zpool
>  state: ONLINE
>   scan: none requested
> config:
> 
>     NAME                               STATE     READ WRITE CKSUM
>     zpool                              ONLINE       0     0     0
>       mirror-0                         ONLINE       0     0     0
>         diskid/DISK-WD-WMC1P0DFSF47p2  ONLINE       0     0     0
>         diskid/DISK-WD-WMC1P0DEFERYp2  ONLINE       0     0     0
>     logs
>       gpt/zil0                         ONLINE       0     0     0
>     cache
>       gpt/cache0                       ONLINE       0     0     0
> 
> errors: No known data errors
> 
> Here is the output of zfs-stats -L:
> ------------------------------------------------------------------------
> ZFS Subsystem Report                Mon Oct 20 19:29:38 2014
> ------------------------------------------------------------------------
> 
> L2 ARC Summary: (DEGRADED)
>     Passed Headroom:            72.42m
>     Tried Lock Failures:            360.55m
>     IO In Progress:                65
>     Low Memory Aborts:            101
>     Free on Write:                7.09k
>     Writes While Full:            16.90k
>     R/W Clashes:                11
>     Bad Checksums:                19.48k
>     IO Errors:                1.50k
>     SPA Mismatch:                1.18m
> 
> L2 ARC Size: (Adaptive)                555.88    GiB
>     Header Size:            0.21%    1.17    GiB
> 
> L2 ARC Evicts:
>     Lock Retries:                10
>     Upon Reading:                0
> 
> L2 ARC Breakdown:                272.76m
>     Hit Ratio:            0.35%    949.30k
>     Miss Ratio:            99.65%    271.81m
>     Feeds:                    2.19m
> 
> L2 ARC Buffer:
>     Bytes Scanned:                20.45    PiB
>     Buffer Iterations:            2.19m
>     List Iterations:            139.97m
>     NULL List Iterations:            5.58k
> 
> L2 ARC Writes:
>     Writes Sent:            100.00%    567.37k
> 
> Any help is welcome. Best regards
> 


-- 
Andriy Gapon