very large mondcss segments do not impact performance, only small ones
do.
B
On Mar 30, 2010, at 11:21, RPN01 <[email protected]> wrote:
Our MONDCSS grew, perhaps too large, while fighting this type
message a long
time ago. Once the problem was resolved, we didn't attempt to back
off the
changes we'd made, and the large size doesn't seem to hurt anything
at the
moment. I know that ultimately, making the segment larger was not
the answer
to the problem at the time, either.
Also, Mr. Nunsford says hello.
--
Robert P. Nix Mayo Foundation .~.
RO-OE-5-55 200 First Street SW /V\
507-284-0844 Rochester, MN 55905 /( )\
----- ^^-^^
"In theory, theory and practice are the same, but
in practice, theory and practice are different."
On 3/30/10 12:57 PM, "Eginhard Jaeger" <[email protected]> wrote:
There is no single 'right' MONDCSS size for all systems: it's about
performance,
so 'it depends'. The MONDCSS has to be large enough to allow the CP
monitor
to place all the monitor records you told it to collect in that
storage
area. Since
most users just go and enable whole domains, it's the domains
generating the
largest
number of monitor records that one wants to watch. For sample
records that
is,
on most systems, the I/O domain, where you could end up with tens of
thousands
of devices already years ago when I still worked with VM. Be aware
that the
monitor will create a device activity record 3 of 268 bytes and a
cache
activity
record 4 of 264 bytes for each DASD, and they must all fit
simultaneously
into
the MONDCSS, together with all the other monitor records.
(And, as mentioned in another append, the default SAMPLE CONFIG
size is
often too small for so many devices and has to be made larger.)
But there's one general rule that has not yet been mentioned in
this thread:
don't
let the MONDCSS overlay the storage of the virtual machine that is
doing the
data collecting, in this case PerfKit, or it will not be able to
use it.
While your MONDCSS looks VERY large to me, I'm admittedly out of
date as
far as current I/O configurations are concerned, and you apparently
ended up
with it for a good reason, after a trial and error phase with
smaller sizes.
Can you tell me the number of I/O devices that your VM sees and is
collecting
data for?
Eginhard
----- Original Message -----
From: "Bill Munson" <[email protected]>
That does not look like it is large enough.
here is my definition
MONDCSS CPDCSS N/A 08000 0FFFF SC R
It can work for a while but if the segment is not large enough it
will
soon fail.
