gjournal: FLUSHCACHE timed out

[Eric Anderson]

Andriy Gapon wrote:
> Couple of days ago I started using gjournal on FreeBSD 6.2 using a patch
> from here:
> http://people.freebsd.org/~pjd/patches/gjournal6.patch
> 
> I actually had to make 4 minor and obvious tweaks to the patch to make
> it apply cleanly to my src.
> I started to get the following messages sometimes:
> 
> kernel: ad4: FAILURE - FLUSHCACHE timed out
> kernel: GEOM_JOURNAL: Flush cache of ad4s1ge: error=5.
> kernel: ad4: FAILURE - FLUSHCACHE timed out
> kernel: GEOM_JOURNAL: Flush cache of ad4s1ge: error=5.
> kernel: ad4: FAILURE - FLUSHCACHE timed out
> kernel: GEOM_JOURNAL: Flush cache of ad4s1ge: error=5.
> vvvvvvvvv this one is unusual and is found only once
> kernel: handle_workitem_freeblocks: block count
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Ok, that's interesting.. Other threads are talking about a similar 
warning, not related to gjournal.


> ad4s1ge (please don't pay attention to its slightly unusual name, this
> is for historic reasons) is a journal partition/consumer for my /var
> filesystem/partition/provider.
> Size of /var is 16G, size of the journal is slightly less than 1G (1G -
> 32 sectors actually). /var is UFS2 with softupdates enabled.


Pawel, correct me if I'm wrong here - but I think you really need to 
turn *off* softupdates on gjournaled file systems.


> I noticed that I get these messages only when I run 'dump' on any of my
> filesystems. I think that dump is using /tmp or /var/tmp for some
> temporary data and in my setup both of those are in /var filesystem.
> 
> So my I guess is that /var is being written "too" actively and I have to
> tune some parameters to make things smooth.

A few things to note:

- you can turn on 'async' option for your gjournaled file system, and 
get better performance
- you might be able to at the 'noatime' option to your file system mount 
also
- You might try turning your journal switch time from 10 down to 5, and 
see if it alleviates some pressure on your disk.


Eric