I have pound configured to distribute load among 4 machines.

I want to do some tests on one of the machine, and thus, I need to 
remove it from the load balancer. Prerequisite:
- don't destroy existing connections to machines which should stay in 
the balancer
- existing connections to the machine which should leave the balancer 
should be kept for some time


Is it enough if I just comment this machine out in pound.conf, and send 
HUP signal to pound? Or will it break existing connections to the other 
machines (which should stay in balancer)?

According to the fine manual for version 2.4.3 it should work just fine 
this way ("Grace" config option), but I'm not sure how it would behave 
in version 2.0 of pound, which is shipped with Debian Etch.

[...]

I would try just changing the IP address of the server that you want out
of the pool.  Pound will check on it eventually and will take it out
since it can't connect to it.  Once you're done with your testing, I'd
change it back to what it was.

--Alfonso 

-----Original Message-----
From: Tomasz Chmielewski [mailto:mangoo(at)wpkg.org] 
Sent: Wednesday, July 23, 2008 11:38 AM
To: pound(at)apsis.ch
Subject: [Pound Mailing List] removing one server from balancer (without
offline) - how?

I have pound configured to distribute load among 4 machines.

I want to do some tests on one of the machine, and thus, I need to
remove it from the load balancer. Prerequisite:
- don't destroy existing connections to machines which should stay in
the balancer
- existing connections to the machine which should leave the balancer
should be kept for some time


Is it enough if I just comment this machine out in pound.conf, and send
HUP signal to pound? Or will it break existing connections to the other
machines (which should stay in balancer)?

According to the fine manual for version 2.4.3 it should work just fine
this way ("Grace" config option), but I'm not sure how it would behave
in version 2.0 of pound, which is shipped with Debian Etch.


--
Tomasz Chmielewski
http://wpkg.org

--
To unsubscribe send an email with subject unsubscribe to pound(at)apsis.ch.
Please contact roseg(at)apsis.ch for questions.

--
This message has been scanned for viruses and dangerous content by
SecureMail, and is believed to be clean.

Alfonso Espitia schrieb:[...]

But then, all existing connections will be gone.

I don't want that - I could break someone's (online) work this way 
(filling long forms etc.)

[...]

Tomasz Chmielewski wrote:[...][...][...]

Pound doesn't really support this AFAIK.  If you happen to be using 
apache 2.2 (maybe 2.0 as well?), do a 'apachectl graceful-stop' on the 
backend to stop accepting new connections.  The graceful stop will 
continue to serve current clients, but refuse new ones.

When you're satisfied that things are closed, you can take the server 
out of your pound config, or change the IP as previously suggested.

Regards,[...]

Dave Steinberg schrieb:[...][...]
>>> I would try just changing the IP address of the server that you
want out
>>> of the pool.  Pound will check on it eventually and will take it
out
>>> since it can't connect to it.  Once you're done with your testing,
I'd
>>> change it back to what it was.[...][...]

Indeed, thanks for the tip.

[...]

Tomasz Chmielewski wrote:[...][...][...]
I thought that is what poundctl is supposed to do, but with sessions 
rather than connections.

 From the poundctl man page:
       -B/-b n m r
              Enable/disable  a  back-end.  A  disabled  back-end  will 
not be
              passed requests to answer. Note however that  existing  
sessions
              may still cause requests to be sent their way.

We tried this with an older release and it seemed to work well except 
that it seemed to occasionally
cause all of the sessions to be expired at once :(

This would be really useful for us on our production system if it works 
properly now.
[...]