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[lvs-users] LVS connection capacity.

To: "LinuxVirtualServer.org users mailing list." <lvs-users@xxxxxxxxxxxxxxxxxxxxxx>
Subject: [lvs-users] LVS connection capacity.
From: Benjamin Cleyet-Marrel <benjamincm@xxxxxxxxx>
Date: Tue, 25 Sep 2007 13:38:12 +1200
Hi,

I am struggling a bit to understand the maximum connection capacity of a 
director.
As I understood, each connection worth 128Bytes of memory which means a 
1GB server can handle more than a Million connection.

Fine. But there is also this Linux  "port available" limitation which if 
I understood correctly would reduce the number of
of possible connection to about (65k-1024) * number of real servers.
Which can be a bottle neck as the infamous TIME_WAIT connections are 
counted as part of those connections.

I am using a LVS-NAT director so I am not really using local port for 
each connections which make this second limitation a non sens to me.
In theory I could have (65k-1024) * number of real server * number of 
client IP  which anyway would be much bigger than the first memory 
limitation.

Is this correct ?


The other question is around kernel tcp parameters.

I don't really like to mess around with tcp parameters, but it is 
possible to limit the effect of TIME_WAIT by using tcp_reuse. Now, I 
know that lvs handle it's own tcp parameters like time_wait timeout for 
instance so does it also handle it's own tcp_reuse mechanism ?

Thanks for your input.

Cheers
Ben

-- 

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Benjamin Cleyet-Marrel
Consultant

OSS: Open Systems Specialists Ltd
phone:   09-984-3000
fax:     09-984-3001
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email:   bcm@xxxxxxxxx
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