Eginhard,

Yes it was trial and error - and we made it LARGE enough not to fail again

In our Largest LPAR we have 80 guests running - 52 are LINUX guests. 
70 mod27's and 75 mod3's for (paging) and one mod9 the RES pack.

we have 5 VM lpars and all lpars can see the other dasd, though not 
attached to the system, 
only the dasd for each LPAR is attached to that system, we do not vary off 
anything but the MVS dasd 

q monitor 
MONITOR EVENT ACTIVE    BLOCK    4     PARTITION    16384
MONITOR DCSS NAME - MONDCSS 
CONFIGURATION SIZE      800 LIMIT         1 MINUTES 
CONFIGURATION AREA IS FREE 
USERS CONNECTED TO *MONITOR - ESAWRITE 
                              LINMON 
                              PERFSVM 
 
MONITOR SAMPLE ACTIVE 
               INTERVAL    1 MINUTES 
               RATE     1.00 SECONDS 
MONITOR DCSS NAME - MONDCSS 
CONFIGURATION SIZE     1500 LIMIT         1 MINUTES
CONFIGURATION AREA IS FREE 
USERS CONNECTED TO *MONITOR - ESAWRITE 
                              LINMON 
                              PERFSVM 

munson
201-418-7588




Eginhard Jaeger <e.jae...@ch.inter.net> 
Sent by: The IBM z/VM Operating System <IBMVM@LISTSERV.UARK.EDU>
03/30/2010 01:57 PM
Please respond to
The IBM z/VM Operating System <IBMVM@LISTSERV.UARK.EDU>


To
IBMVM@LISTSERV.UARK.EDU
cc

Subject
Re: [?? Probable Spam]  Re: Perfkit SAMPLE CONFIG size too small






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" <william.mun...@bbh.com>
>
>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.


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