Zfs heavy io writing | zfskern txg_thread_enter

[Michelle Sullivan]

Niccolò Corvini wrote:
> Hi, first time here!
> We are having a problem with a server running FreeBsd 9.1 with ZFS on a
>   
You should upgrade to a supported version first...  9.3 would probably
be the best (rather than 10.x) as it's still supported and uses the same
ABI (ie you should need to reinstall all your ports/packages - though
you should because it sometimes breaks things - at least check for
broken things :) .)

If you're not familiar "freebsd-update -r 9.3-RELEASE upgrade" will help
you do it without too many problems.

> single sata drive. Since a few days ago, in the morning the system becomes
> really slow due of a really heavy io writing. We investigated and we think
> it might start at night, maybe correlated to to crondaily (standard) but we
> are not sure.  After a few hours the situation returns to normal.
>   
Yeah this sounds like something I am quite familiar with...  It's the
security check cronjob that runs every day... its looking for any
setuid/setgid files, new/modified files...etc... across all file systems

> Any help is much appreciated
> The machine is a Intel Xeon E5-2620 with 36GB of RAM, the HDD is a 2TB an
> is half full.
> gstat output:
>
>  
>  PID JID USERNAME   VCSW  IVCSW   READ  WRITE  FAULT  TOTAL PERCENT COMMAND
>     3   0 root         14      1      0     37      0     37  30.33%
> [zfskern{txg_thread_enter}]
> 49866 215   7070       26      2      0      5      0      5   4.10%
>
>   

> 93400   0 root         13      0     10      0      0     10   8.20% [find]
>
>   

> 98335 120 root         11      0     29      0      0     29  23.77% find
> /var/log -name messages.* -mtime -2
> 16128 214     70        8      0      0      1      0      1   0.82%
> sendmail: ./u1J9k90d001112 local: client DATA status (send
>  1120 198 root          7      0      0      4      0      4   3.28%
> mail.local -l
>
>   

You'll find it kicked off from /etc/periodic/daily/ with a config option
you can find in /etc/defaults/periodic.conf (or /etc/periodic.conf or
/etc/periodic.conf.local )...

Regards,

-- 
Michelle Sullivan
http://www.mhix.org/