[CentOS] real used RAM!

On Mon, 2005-05-30 at 10:10 -0500, israel.garcia at cimex.com.cu wrote:
> List, I've installed my CentOS Server running progress 9.1D database
> system, with only 15 users working every day, this server has 2GB RAM,
> so, my question is: 
> Why the 2GB of RAM is always used? Even with only one user connected...
> How can I messuare the real RAM MEM used by my system split in proccess?
> Is there another tools which I use to compare the results from top. Or
> vmstat?

There is vmstat, iostat, etc... all sorts of things for tracking memory,
I/O and other usage.

The Linux kernel is very dynamic when it comes to how it manages user,
buffer and cache.  It's a very efficient approach that works well.  In
dealing with databases, you're going to have very large reads/commits
that will be cached/buffered, as well as the binaries involved (which
can be very extensive).  So the kernel will typically be using all of
your memory at any time, although it will drop cached as soon as it
needs it for user or buffers.

BTW, on anything but an AMD64 platform, 2GB can be a "weak spot" in
memory size.  You typically either want to be 1GB (actually, 960MB), or
4GB+, because of the performance hit that occurs when you use the 4/4GB
model versus the 1/3GB model for anything but AMD64 (even Intel EM64T
has some issues with its 32-bit AGTL+ physical platform).

Just something to be wary of.  It will depend on your application if
2GB is better than 1GB on a 32-bit physical Intel/AMD platform, instead
of AMD64 (which is a 40-bit physical platform).


-- 
Bryan J. Smith                   mailto:b.j.smith at ieee.org
----------------------------------------------------------
Beware of those who define their preferences in terms of
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