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While your MONDCSS looks VERY large to me, I'm admittedly out of date as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.
