[users@httpd] Question about graphic-only servers....

["Daniel P. Brown" <da...@parasane.com>]

    Hey, gang, this is my first post to the list (though I've been an 
Apache user for over a decade now).  My question to the experts in the 
field is relatively simple, but I'd like to get some insight from a 
group instead of relying on my own [humble lack of] knowledge before 
making the recommendation to my client.  First, the scenario:

    My predominant expertise is in database-driven websites --- a 
good-ol' LAMP setup.  I not only sell dedicated servers out of my local 
datacenter, but also administer them - and most are load-balanced 
clusters of two to six servers each.  This type of work isn't a problem 
for me, but instead a simpler, more 1992-esque problem puzzles me a bit.

    One of my customers is using a load-balanced set of four servers.  
One server is fully-capable of handling the MySQL databases and PHP 
webpages with no problems at all.  However, he has three additional 
servers so far, all 100Mbps unmetered, for large graphic distribution 
using randomized load-balancing handled by PHP.  Things went well for a 
while, and the servers handled the requests promptly and fully.  
However, the traffic has increased quite a bit, and this weekend we're 
expecting it to increase as much as tenfold.

    What would be our best option for ensuring the GRAPHIC servers can 
handle this drastic increase in traffic?

    Should we....

          .... add another server to the cluster?
          .... double the RAM on each 2.0GHz Dual Xeon from 2GB to 4GB 
(the maximum)?
          .... upgrade to faster CPU's?
          .... give up all hope and pack it in, then worship the old 
Boo.com website and it's brilliant decisions?

    Thanks, all.  I'm looking forward to reading your responses.

-- 
Daniel P. Brown
Chief Forensic Investigator, Founder
http://www.parasane.com/
daniel.brown@parasane.com
(724-) 513-9692


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Re: [users@httpd] Question about graphic-only servers....

["Mark H. Wood" <mw...@IUPUI.Edu>]

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What you need more of depends on what you are about to run out of.  If you
always have plenty of free memory, adding more RAM won't help.  If the
load average is always low, adding more CPUs won't help.

You also need to look at how hard your network connections are being
driven.  For example, if you are expecting a tenfold increase in traffic
and your interfaces are averaging 70% of capacity, you may need more or
faster NICs.

You need to look at the bandwidth of your storage too.  Throwing memory at
the problem can help up to a point, but you could get into a situation
where it's just not possible to fill memory fast enough to meet demand.
More disks on more controllers might be indicated.

You'd need more complete servers if the limiting factor is bus bandwidth.

You need to start by measuring a lot of things to see where the
bottlenecks are.  (After you overcome the first one, you'll find a second
one right behind it.  Performance management is the art of rearranging
bottlenecks until you don't reach them.)

- -- 
Mark H. Wood, Lead System Programmer   mwood@IUPUI.Edu
Open-source executable:  $0.00.  Source:  $0.00  Control:  priceless!

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