On Monday 15/08/2011 at 6:37 am, Chris Ferebee wrote:
The numbers of simultaneous connections allowed by the default settings in SurgeMail seem very conservative to me. For example, G_CON_PERIP is initially set to 15 or 20 (I forget which). I am testing our new SurgeMail server with four of my own (high-load) IMAP accounts, most of them set up on two or three Macs and two iPhones.
All the devices are behind one NAT router and are thus using the same public IP, and already I have gotten error messages about refused connections, apparently caused by the G_CON_PERIP setting. After I lifted the G_CON_PERIP limit, the errors went away.
Yep, when you have a user population behind a nat you need to increase it. Normally this is an all or nothing thing, The default settings give good protection from lots of simple abuse. And so we
error on the side of caution here. 95% of systems have less than a thousand active users (this is just reality, for every big server there are 20 small servers), most of these limits help prevent
simple load problems caused by too many connections which are rarely genuine, it prevents 'melt downs' which can be very hard to figure out 'after' the system is sitting in a melted heap on the floor. Also many of these limits were initially setup a few years back when a 'server' had to survive with 200mb of ram installed :-) But yes just bump up any limit that complains (The limits all tell you what they are when they are hit)
Maybe you are right and that limit is just annoying these days, I'll have a think about that...
I will be putting various client domains on the server, some of them using 50-100 accounts through one IP. I have a 1000 user license and anticipate having at least 500 active IMAP accounts. Looking at the various connection limits, it seems to me that I will have to raise them all by a very large margin.
The server is currently running on Debian Linux Lenny (soon Squeeze) 64-bit, with 8 GB of RAM.. Should I expect problems if I try to allow something on the order of 10,000 simultaneous IMAP, POP, SMTP and Webmail connections?
I don't quite follow, why would you test with 10000 connections for a 500 active users ? But back in the day, linux would crash (and I mean the operating system, not surgemail) if you went over 1000 threads. So some of these paranoid limits are to prevent the operating system failing catastrophically if it hasn't been tuned for the load (or hasn't got enough ram installed). (debugging the system crashing is not nice so it's better if surgemail stops the load before that occurs). A modern linux won't have this problem but may need some system settings adjusted to work (check the handle limit in surgemail_start.sh as that's the primary point of failure)
SurgeMail will be happy with about 2000 connections on most systems, If you really need to go above that get back to me and we can work on any issues you hit.