Zero-Downtime Servicing of a Varnish Server Behind a F5 BIG-IP

Javier Casares javier at
Mon Jul 9 22:59:43 CEST 2012


        Units: seconds
        Default: 5

    Idle timeout for persistent sessions. If a HTTP request has not
been received in this many seconds, the session is closed.


Javier Casares

2012/7/9 Steven Engelhardt <sengelha at>:
> I have two Varnish servers behind a F5 BIG-IP load balancer.  Both servers
> are constantly active and serving ~5,000 requests/second 24x7.  Clients
> aggressively use HTTP 1.1 Keep-Alives.
> I'm looking to develop a process for servicing and upgrading the Varnish
> servers which results in 0 downtime to the client.  Our normal process for
> performing changes on production servers is:
> 1. Mark the server as disabled in the BIG-IP
> 2. Wait for the connections on the server to drop to 0
> 3. Service the machine
> However, because of the aggressive and constant use of HTTP Keep-Alives,
> clients virtually never drop their connections, and the machine continues to
> serve traffic for quite a long time after it is disabled in the BIG-IP.
> Is there a way to tell Varnish to aggressively close all client HTTP
> connections?
> Thank you,
> Steve
> --
> Steven Engelhardt
> sengelha at
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