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General question regarding handling dead backends
Galen Charlton <gmc(at)esilibrary.com>		 2012-06-21 18:55:58 [ FULL ] 
Hi,

We are considering using Pound for load-balancing HTTP requests across a set of
Apache backends.  We frequently need to take backends out of rotation
temporarily in order to perform maintenance, but ideally this would happen in a
controlled fashion.  In particular, we'd like to be able to tell Pound to stop
sending new requests to a backend without disrupting any current HTTP
connections between that backend and its clients.  Is that sort of controlled
quiescing of a backend possible?

Regards,

Galen
--
Galen Charlton
Director of Support and Implementation
Equinox Software, Inc. / The Open Source Experts
email:  gmc(at)esilibrary.com
direct: +1 770-709-5581
cell:   +1 404-984-4366
skype:  gmcharlt
web:    http://www.esilibrary.com/
Supporting Koha and Evergreen: http://koha-community.org & http://evergreen-ils.org
Re: [Pound Mailing List] General question regarding handling dead backends
Neil Skrypuch <neil(at)tembosocial.com>		 2012-06-21 19:14:30 [ FULL ] 
On Thursday 21 June 2012 12:55:58 Galen Charlton wrote:[...]

Yes, specify a HAPort for the backend, which will be used for health checks. 
If the HAPort stops responding, the service should be gracefully pulled out of 
the pool and then you can shut down the regular service.

You will obviously need something listening on the HAPort that you can take 
down separately from your Apache instances.

The documentation has the full details.

- Neil
Re: [Pound Mailing List] General question regarding handling dead backends
Galen Charlton <gmc(at)esilibrary.com>		 2012-06-21 19:16:55 [ FULL ] 
Hi,

On Jun 21, 2012, at 1:14 PM, Neil Skrypuch wrote:[...]

Thanks much -- I suspected that this might be the case, but having confirmation
definitely helps.

Regards,

Galen
--
Galen Charlton
Director of Support and Implementation
Equinox Software, Inc. / The Open Source Experts
email:  gmc(at)esilibrary.com
direct: +1 770-709-5581
cell:   +1 404-984-4366
skype:  gmcharlt
web:    http://www.esilibrary.com/
Supporting Koha and Evergreen: http://koha-community.org & http://evergreen-ils.org
RE: [Pound Mailing List] General question regarding handling dead backends
Joe Gooch <mrwizard(at)k12system.com>		 2012-06-21 19:40:32 [ FULL ] 
If you use HAPort, it'll use that to determine the backend is down.  When a
backend is dead, all sessions connected to that backend will be immediately
terminated.

Use poundctl to disable the backend.  Sessions attached to the backend will
continue to be sent there until the session expires.  But no new sessions will
be sent to that backend.  Then re-enable the backend when you're done.

Joe

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