[hobbit] Monitoring memory on AIX

[Stef Coene]

On Thursday 01 March 2007 16:16, Stef Coene wrote:
> Henrik (and others), any comments on this post ?
Since no one wants to respond, I will do it myself ;)

> > Henrik : The only problem is that Total for the line Actual is always the
> > amount of Physical Memory.  But this should be Physical Memory + Swap
> > Memory. At least, this is for AIX, but I think this is for other os'es as
> > well.  I think this is a bug.
> >
> > The problem is that Actual can be > 100%.  
The problem with using Accessed Virtual Memory as monitoring for memory usage 
is that this can be more then 100%.  This numbers is inflated on AIX.  I 
still don't know how this can, but AIX does pre-allocation for swap.  So some 
parts of memory have a copy in cache and are counted twice.

Anyhow, this number is still important to monitor.  But some special care is 
needed.  First of all
- Actual can be > 100%
- the maximum for Actual is amount of memory + swap (currently this is only 
the amount for memory)
- for AIX, the warning and error thresholds for Actual needs to set higher 
because this number is bigger then you would normally expected.

See my first post for some patches.


Stef