I'm not going to claim to understanding any of the nuances, but maybe
this redpiece will help:
Multiple z/OS Virtual Machines on z/VM
http://www.redbooks.ibm.com/abstracts/redp4507.html
On 05/22/2010 01:36 PM, TaeMin Baek wrote:
We are using GRS ring mode in three OS/390 V2.10 in Baseplex
enviroment under z/VM v6.1 on z10
to share DASD and dataset with serialization between OS/390 guests and
z/VM provide shared full-pack minidisk
with using virtual RESERVE/RELEASE.
While system is running, Suervisor CPU usage is high up to 30%~40% of
Total CPU Usage on Performance Toolkits.
ex) Total CPU % : 67.4%
Superv. CPU : 29.8%
Emulat. CPU : 37.6%
When one guest OS/390 access to a certain dataset,
1) z/VM CP control the DASD and set it reserved
2) if other OS/390 guest try to access different dataset in same DASD,
it must wait
and CP continue to check until DASD is released.
Is the above logic of shaing DASD is right?
If it is right, i think GRS is useless now and it can give more
workload to CP.
Today we tried to change sharing DASD method from with using Virtual
Reseve/Release to without using Virtual Reseve/Release.
What i mean is that i don't use MDISK with 'V' option. Only define
MDISK with 'MW' option.
I want to let GRS in OS/390 to control dataset level sharing like in
Native LPAR mode.
I guess it might reduce the CP workload relate to reserve/release DASD.
But the problem is JES failed to start because it cannot access the
volume containg checkpoint dataset.
The message said the volume containing checkpoint dataset is not shared.
Is there anybody who use GRS in Sysplex or Baseplex?
Do you use GRS and Sharing DASD with Virtual Reseve/Release?
How is your CPU utilization? Supervisor CPU% is high like us?
Is there any tuning point to reduce the Supervisor CPU Usage?
Regards
------------------------------------------------------------------------
*Tae Min Baek* Mmaa Bldg, 467-12 Dogok-Dong
Advisory IT Architect Seoul, 135700
z/Linux Team Korea
IBM Sales & Distribution, STG Sales
Phone: +822-3781-8224
Mobile: +82-010-4995-8224
e-mail: tmb...@kr.ibm.com
--
Rich Smrcina
Phone: 414-491-6001
http://www.linkedin.com/in/richsmrcina
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