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Salah Abdulla wrote:
>
> Good day,
>
> We are running ldirectord wlc mode with 4 similir apache real servers.
> Recentlry, we have been receiving complians from users saying that sometimes
> when clicking on a link in a web page nothing happens and by clicking one
> more time the page is displayed immediatly. We do have a ipcheck software
> monitring the HTTP and it also complians saying HTTP is down more often
> recently. We increased the presisstance from 300 to 600 and still no luck.
> The average number of TIME_WAIT connections from "ipvsadm -lcn|grep
> "TIME_WAIT"|wc -l" is 700 and the average number of ESTABLISHED connections
> from "ipvsadm -lcn|grep "ESTABLISHED"|wc -l" is 145. All MTUs of all
> interfaces(director+realservers) are set to 1500. The timeout is set for
> tcp=900 , fin=120 & udp=300.
>
> Any advise why a page is not displayed the first click and why ipcheck is
> complianing while all webservers are up and running?
>
> One thing i would add is that all the 4 web servers their memory utilization
> is very high.
This could be a difficult one. We haven't yet had a story where LVS has had
bad performance, so I would look elsewhere first. Here's a story to illustrate
http://www.austintek.com/LVS/LVS-HOWTO/HOWTO/LVS-HOWTO.wisdom.html#freeze
When you say memory ulitisation is high, this may not be a problem. If the
machine
has been running long enough (hours), Linux will allocate all the memory. I'd be
more concerned if a lot of swap was allocated. Start looking for other things,
how
busy are the disks? The number of ESTABLISHED and TIME_WAIT connections is not
high.
Have you optimised your realservers. Look at Dan Kegels article, linked from
http://www.austintek.com/LVS/LVS-HOWTO/HOWTO/LVS-HOWTO.performance.html#performance_articles
and for the tuning that squid people do (start at
http://www.austintek.com/LVS/LVS-HOWTO/HOWTO/LVS-HOWTO.performance.html#squid_hints)
Joe
--
Joseph Mack PhD, High Performance Computing & Scientific Visualization
SAIC, Supporting the EPA Research Triangle Park, NC 919-541-0007
Federal Contact - John B. Smith 919-541-1087 - smith.johnb@xxxxxxx
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