[Xymon] Redhat Memory Question

[Jeremy Laidman]

On Fri, Mar 20, 2015 at 2:25 AM Neal, Jonathan W via Xymon <xymon at xymon.com>
wrote:

> I have never monitored any Redhat systems before, all Solaris in the past
> for the most part.  Since top and free always show all the physical memory
> in use on Redhat, how do people monitor memory usage accurately with Xymon?


Xymon tracks swap usage, physical memory usage, and "actual" memory usage.
The last of these is what most people care about.  In analysis.cfg you can
set thresholds on any of these.  On my system the thresholds for physical
memory usage are 100% for yellow and 101% for red.

Under Linux, "actual memory" is obtained from the output of "free" which is
recorded in the [free] section of the client data, specifically from the
"buffers/cache" line.  The value for "actual used" comes from the first
number.  The "actual total" is the total physical memory and is the first
number in the "Mem:" line.

  Currently the Memory tag shows as yellow under this new Redhat server,
> though in my mind it should be green.
>

For actual memory usage, yes.

Mem:  16435916k total, 16311612k used,   124304k free,  6255112k buffers
> Swap: 18481144k total,        0k used, 18481144k free,  6391000k cached
>
>              total       used       free     shared    buffers     cached
> Mem:      16435916   16311588     124328          0    6255116    6391040
> -/+ buffers/cache:    3665432   12770484
> Swap:     18481144          0   18481144
>

In your case, on your "memory" status page you would see "Actual 3579M
16050M 22%" meaning 3.5GB non-cache/buffer RAM usage used out of 16GB total
physical RAM, which is 22%.

So actual usage is 22%.  If your yellow threshold for MEMACT is the default
of 90, then this 22% is well short of triggering a yellow condition.  And
it must be something else.

On your memory status page each line should have its own coloured dot.
Which of the lines has a yellow dot?  I'm guessing it's the "Physical", and
someone has modified the MEMPHYS threshold in analysis.cfg to go yellow at
99% instead of 100%.

J
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