High avaliabilty for IMAP/PROXY

Marc Patermann hans.moser at ofd-z.niedersachsen.de
Mon Sep 22 09:09:13 EDT 2014

ktm at rice.edu schrieb (18.09.2014 21:43 Uhr):
> On Thu, Sep 18, 2014 at 12:07:57PM -0700, Vincent Fox wrote:
>> On 9/18/2014 11:58 AM, Fabio S. Schmidt wrote:
>>> Does anyone have any better ideas to improve the high availability? I
>>> was wondering about using HAPROXY vs NGINX but I do not know their
>>> behaviours in cases like I mentioned above.
>> We have for about 8 years used Perdition for POP/IMAP proxy.
>> 3 simple Linux boxes in a load balanced pool.
>> Friends don't let friends do Round Robin DNS.  You can't count
>> on removing DNS entries, since propagation can be very slow and
>> some clients don't even respect TTL.
> We also used Perdition here for our POP3/IMAP proxy. Unfortunately, its
> process per connection resulted in an enormous resource footprint when
> everyone was connected to the server. In addition, the startup stampede
> of processes completely swamped the frontends crippling the performance
> until a steady state was reached. As a result, we moved to using NGINX
> as our POP3/IMAP proxy. Now a single-box can carry the connection load
> that 4 or more boxes struggled with along with better responsiveness
> and performance to boot.
> These are all located behind our Citrix Netscaler boxes. You should
> be able to replicate their function with either haproxy or nginx.
What does the Netscaler do in this scenario?


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