System apparently unable to cope with loading

[Rob Tweed]

I have a customer who is having problems when their Windows
2000/IIS/PHP-based system begins to experience a level of loading that
isn't, in my view, unreasonably high. I'm wondering what others
think, specifically:

- are these volumes, for this kind of configuration, at or beyond the
levels at which PHP should be able to cope? I hope not !

- what might be done to alleviate these problems? One of our
suspicions is that Windows 2000/IIS/PHP is unable to cope at these
volumes (for whatever reasons) but a Linux/Apache/PHP configuration
would be more stable and cope with the required volume levels.

- Is the Windows/IIS/PHP configuration inherently flawed?

- What kind of volumes should we be able to expect with
Linux/Apache/PHP?

- How many web servers would be the norm for these volumes?
Here's the current config:

F5 load balancer fronting 4 web servers.

The web servers are each dual-processor Intel machines running IIS5
under Windows 2000. Over 500Mb memory is still available when IIS
gives up, so they aren't memory-constrained.

PHP 4.3.6 in CGI mode, with the Zend Accelerator included

Required volumes:

30,000 to 100,000 page views per hour

The customer sees problems with PHP at less than 3,000-4,000 page
views per hour. The webservers were only doing 20% until they spiked
to 100% and then went back to zero - it seems that at a particular
level of loading, IIS closes down and restarts itself, then runs till
the loading hits a threshold again and the cycle repeats.
---
Rob Tweed
M/Gateway Developments Ltd

Global DOMination with eXtc : http://www.mgateway.tzo.com
---

[Michael Austin]

Rob Tweed wrote:

I have a customer who is having problems when their Windows
2000/IIS/PHP-based system begins to experience a level of loading that
isn't, in my view, unreasonably high. I'm wondering what others
think, specifically:

- are these volumes, for this kind of configuration, at or beyond the
levels at which PHP should be able to cope? I hope not !

- what might be done to alleviate these problems? One of our
suspicions is that Windows 2000/IIS/PHP is unable to cope at these
volumes (for whatever reasons) but a Linux/Apache/PHP configuration
would be more stable and cope with the required volume levels.

- Is the Windows/IIS/PHP configuration inherently flawed?

- What kind of volumes should we be able to expect with
Linux/Apache/PHP?

- How many web servers would be the norm for these volumes?
Here's the current config:

F5 load balancer fronting 4 web servers.

The web servers are each dual-processor Intel machines running IIS5
under Windows 2000. Over 500Mb memory is still available when IIS
gives up, so they aren't memory-constrained.

PHP 4.3.6 in CGI mode, with the Zend Accelerator included

Required volumes:

30,000 to 100,000 page views per hour

The customer sees problems with PHP at less than 3,000-4,000 page
views per hour. The webservers were only doing 20% until they spiked
to 100% and then went back to zero - it seems that at a particular
level of loading, IIS closes down and restarts itself, then runs till
the loading hits a threshold again and the cycle repeats.
---
Rob Tweed
M/Gateway Developments Ltd

Global DOMination with eXtc : http://www.mgateway.tzo.com
---

30K-100K hits/hr... Hmmmm.

First, you have to remember that with each "hit" the PHP page must be
"interprete d" (compiled+execu ted) and the time it takes to do that will
vary from page to page, depending in the page complexity.

Let's see... that breaks down to 8.3/sec to 27.7/second. I have seen
numbers that would suggest "a well tuned IIS server should be able to
handle 50 Get requests per second", but does not say what the payload
size should be to achieve those numbers either. Also, due major changes
in the IIS6 server, you should probably upgrade... But as always, YMMV.

Exactly what does the payload look like? Is it Dynamically generated
pages (I assume yes since you are using PHP)? When you load "a page"
how much data is it transferring? (HTML+CSS+JPG+G IF...) If you are
running at 100Mbits/sec=(128KBytes/second)... so, if the pages being
loaded are larger that 128KB Each, well... you do the math...

IMPO (in my professional opinion), anyone using Wxx/IIS as a front-line
web server needs to have his head examined. Until M$ can fix the
Swiss-cheese Security, your data (and if I visit your site, my data) is
at risk of compromise. Not to mention the amount of downtime your
client will endure when the "latest" vulnerability is discovered and
exploited - and you nor the AV software company can guarantee they will
have a fix and get your system updated before it does hit.

Linux is less vulnerable and will run faster on the same equipment.
Unless you are bound to M$ applications...

Michael Austin.

[Leythos]

In article <jG************ *****@newssvr22 .news.prodigy.c om>,
ma*****@firstdb asource.com says...

IMPO (in my professional opinion), anyone using Wxx/IIS as a front-line
web server needs to have his head examined. Until M$ can fix the
Swiss-cheese Security, your data (and if I visit your site, my data) is
at risk of compromise. Not to mention the amount of downtime your
client will endure when the "latest" vulnerability is discovered and
exploited - and you nor the AV software company can guarantee they will
have a fix and get your system updated before it does hit.

IMPO, I've not seen any downtime on properly configured MS servers
running anywhere in the world. Sure, ones setup improperly or ones that
were not behind a proper firewall.

We manage servers running 2000 and 2003 all over the country and have
found that not one of them, in the last 5 years, has been compromised.
Most of these servers run the corporate presence for fortune 1000
companies and for private companies. Now, this doesn't mean that IIS
servers are safe, it just means that you need to properly configure them
and know how to protect them behind a firewall - just as with any web
server.
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