Re: Persistance and LVS

To: " users mailing list." <lvs-users@xxxxxxxxxxxxxxxxxxxxxx>
Subject: Re: Persistance and LVS
From: Horms <horms@xxxxxxxxxxxx>
Date: Tue, 27 Apr 2004 21:05:13 +0900
On Tue, Apr 27, 2004 at 11:41:04AM +0100, Malcolm Turnbull wrote:
> pb wrote:


> >   -----------------------------------------
> >Would changing 15 to 60min Persistance on the LVS take
> >up a lot of memory and processing (CPU/load) overhead?
> >We're running 1gb of memory and dual pentium III.
> >   -----------------------------------------
> I would think it would be fine, 1 GB should handle almost 8 million 
> connections in the timeout period i.e. 60 mins (or 2mins with no 
> persistence) Some one clever might correct me on that but I think its true.

I think Malcom is on the money here.

Keep in mind that each connection entry / persistance timeout
consumes something like 128bytes (actually, it might be a bit bigger
now, but it is still in that ball-park). You can do the maths
(actually you should, my brain has already checked out for the day),
but if you are getting 100 connections/s, for an hour, each from
a unique host, then you are still only going to end up using about 
45Mb of memory for persistance entries. I doubt that will hurt you.
I would also be supprised if you are getting connections from
360,000 unique hosts per hour :-)

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