[ic] Should I buy another CPU?

[John Beima]

G'Day Bill,

You know this is a very good question...

Here are my views on it...

We have 1 pIII-1G box with 1 1/2G of RAM serving up 300+ low traffic Interchange
sites. These sites serve about 60 Gigs a month.

We have 2 - Dual PIII-1G boxes with 2Gs of RAM serving up 25 sites a piece. Each
of these boxes serves up 3-4Gs of data a day. So it transfers around 100-120
Gigs a month.

Now in the Dual servers we HAVE to have RAIDed SCSI Utra-160, or the IO just
doesn't keep up. In the first server we are using ATA-100.

What you need to look at for RAM vs. CPU additions is a coupel of things... Run
top for a short period of time to find out your average load factor. If it is
about a .75 on average, you need more CPU power...

Next run "vmstat 2"... Then look at the disk cache. Is it constantly filling and
empting... If it is, that is becuase there isn't enough system memory for your
running applications. So the system dumps the disk cache to free up what it
need. Then it starts building the disk cache again. Given this, you box runs
slower... Because all the reads/writes are always comming off the disk and not
out of cache. So you need to add more RAM.

The second of the two, can cause an artificial CPU load. Expecially if you have
IDE hard drives. That INCLUDES ATA-100 & ATA-133, because despite what you have
been told, they STILL USE the main CPU.

One last thing you need to look at is drive speed and choices.... If you are
experencing on and off failures in pgp encryption and/or payment gateways. This
is more likely than not, your drives are too slow. These programs/modules need
to make tmp files, they also need RAM, and if they can't get both fast enough,
they fail. You will see this problem a lot on the list, if people actually READ
past messsages, they would see it and STOP posting it again and again. 

Anyways if you are having the pgp and/or payment gateway problems you will need
to switch from IDE to SCSI. NO and I mean NO IDE chains and that INCLUDES
ATA-100 and ATA-133 can do much more than 1/2 of what Ultra-160 SCSI can do.
Which will solve the problems with being able to create and read those tmp
files.

So gear if you need a new box, or just additions to your current one by the
above guidelines and you show be on the right track.

I hope this has helped out some...






Quoting Bill Carr <bill@worldwideimpact.com>:

> Debian woody, Kernel 2.4.18, IC 4.8.3, Perl 5.6.1, MySQL 3.23.47 (on
> separate machine).
> 
> Should I buy another PIII 850 for my servers at $225 per unit? I have
> two IC/web servers with 512RAM and one PIII 850 each. I am definitely
> doubling the RAM. I am not sure how much difference the extra CPUs will
> make.
> 
> -- 
> Bill Carr
> Worldwide Impact
> bill@worldwideimpact.com
> 413-253-6700
> 
> _______________________________________________
> interchange-users mailing list
> interchange-users@interchange.redhat.com
> http://interchange.redhat.com/mailman/listinfo/interchange-users
> 



John Beima
jbeima@palb.com, support@alocalagent.com, and support@alocalchurch.com

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