Re: [lvs-users] lvs - how to estimate weights

To: " users mailing list." <lvs-users@xxxxxxxxxxxxxxxxxxxxxx>
Subject: Re: [lvs-users] lvs - how to estimate weights
From: Alex <linux@xxxxxxxxxxx>
Date: Thu, 13 Nov 2008 15:18:03 +0200
> If they're all the same hardware platform, in the same network location,
> running the same application then make their weights equal.

yes, it is. i am using a 3 thiered level cluser implementation (1st - lvs, 2nd 
- n real servers (webservers) using a shared disk file sistem like gfs as 
document root, 3rd - SAN exporting via iscsi blocks used as shared disks in 
2nd thier)
Now, on all our servers i have the same weight (weight=1)

> Ensure you start with (for example) 100/100/100, or 1000/1000/1000. It's
> easier to juggle the weights with those values than 1/1/1 !

Aha, I got the idea... is easyer to set fractions... ;-)

> As Malcolm suggests, see how they run for a while and adjust as
> necessary.

so we can simply say that the weight can not be determined apriori using a 
math formula (before the momment we will start to use balancers)? I would 
like to have some aproximations in order to set up some weight before to 
start our cluster. after that, we can use tuning, to obtain an equilibrated 
distribution to all our servers (as malcolm said no more then 40%CPU usage on 

For example, if i have one P4 at 1.8Ghz and one P3 at 1.8Ghz, can i aproximate 
that P4 is twice good then P3 and set weight=2 on P4?

Or, If we have 2 P4 servers at 1.8Ghz having 125M and 512M RAM, can we 
conclude that second server is 4 time better then first and set weight=4?

Or, If we have two P4 servers at 2Ghz with the same amount of RAM, but on 
first server we are activating Hyper Threading technology, is correct to say 
that server with HT enabled is twice good then another and we can set 
weight=2 on it?


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