Failure cenarios?

[Denis Brækhus]

----- Gaute Amundsen <gaute at pht.no> wrote:
> I have come to understand that in some builds under some conditions
> varnish 
> may hang or a crash. (we run 1.0.4-3el4.i386.rpm)

Hi Gaute,

I'll just say that in my experience Varnish has proven itself to be extremely stable. We actually run 1.0.3 across the board (yes I know there are known bugs, however we do not experience them at all) and Varnish currently serves up all requests at www.startsiden.no and www.abcnyheter.no. If anything breaks, it has not so far been varnish. 

However our scenario is pretty different from yours, we have very few vhosts but each has a very high amount of traffic. There is little or no advanced VCL configuration at all on our sites. We're pretty close to the default. The two sites have a different setup with regards to placement of Varnish. One site runs with dedicated varnish servers, the other has varnish and apache2 on the same box.

> Now the question is, how do I best detect if varnsih should have a
> problem?
> Would it be reasonably reliable to just chek if the pid 
> from /var/run/varnish.pid is running, do I need to fetch a page, or is
> there 
> some better way?

Well, we always monitor as high up as possible to make sure everything works on all levels. Lower level monitoring is useful too, but for pinpointing with more accuracy where the problem is. 

Regards
-- 
Denis Braekhus - Teknisk Ansvarlig ABC Startsiden AS
http://www.startsiden.no