On all systems entered: CP SET MDCACHE STORAGE 0M 100M
q mdc
Minidisk cache ON for system
Storage MDC min=0M max=100M, usage=0%, bias=1.00
Xstore MDC min=0M max=2048M, usage=0%, bias=1.00
Ready; T=0.01/0.01 02:04:03
Presently I have a base VM:Backup running on 2nd level guests.
First level VM:
ind
AVGPROC-091% 01
XSTORE-001013/SEC MIGRATE-0041/SEC
MDC READS-000001/SEC WRITES-000001/SEC HIT RATIO-000%
STORAGE-056% PAGING-0075/SEC STEAL-092%
Q0-00001(00000) DORMANT-00028
Q1-00001(00000) E1-00000(00000)
Q2-00000(00000) EXPAN-001 E2-00000(00000)
Q3-00002(00000) EXPAN-001 E3-00001(00000)
PROC 0000-091%
LIMITED-00000
Ready; T=0.01/0.01 02:09:11
q alloc page
EXTENT EXTENT TOTAL PAGES HIGH %
VOLID RDEV START END PAGES IN USE PAGE USED
------ ---- ---------- ---------- ------ ------ ------ ----
L51PAG 1004 1 3338 600840 239007 425234 39%
LPG002 102C 1 3337 600660 218143 342873 36%
LPG003 102D 1 3337 600660 194654 491228 32%
------ ------ ----
SUMMARY 1760K 651804 36%
USABLE 1760K 651804 36%
Ready; T=0.01/0.01 02:11:45
Guest 1 (development):
ind
AVGPROC-026% 01
MDC READS-000073/SEC WRITES-000003/SEC HIT RATIO-049%
STORAGE-000% PAGING-0001/SEC STEAL-000%
Q0-00000(00000) DORMANT-00007
Q1-00001(00000) E1-00000(00000)
Q2-00000(00000) EXPAN-001 E2-00000(00000)
Q3-00001(00000) EXPAN-001 E3-00000(00000)
PROC 0000-026%
LIMITED-00000
Ready; T=0.01/0.01 02:12:30
q alloc page
EXTENT EXTENT TOTAL PAGES HIGH %
VOLID RDEV START END PAGES IN USE PAGE USED
------ ---- ---------- ---------- ------ ------ ------ ----
PAG001 1003 1 1111 199980 0 0 0%
PAG002 1004 1 1111 199980 0 0 0%
PAG003 1005 1 1111 199980 0 0 0%
------ ------ ----
SUMMARY 599940 0 0%
USABLE 599940 0 0%
Ready; T=0.01/0.01 02:13:16
Guest 2 (test):
ind
AVGPROC-023% 01
MDC READS-000068/SEC WRITES-000006/SEC HIT RATIO-062%
STORAGE-000% PAGING-0001/SEC STEAL-000%
Q0-00000(00000) DORMANT-00012
Q1-00000(00000) E1-00000(00000)
Q2-00000(00000) EXPAN-001 E2-00000(00000)
Q3-00001(00000) EXPAN-001 E3-00000(00000)
PROC 0000-023%
LIMITED-00000
Ready; T=0.01/0.01 02:14:25
q alloc page
EXTENT EXTENT TOTAL PAGES HIGH %
VOLID RDEV START END PAGES IN USE PAGE USED
------ ---- ---------- ---------- ------ ------ ------ ----
PAG001 1008 1 1111 199980 0 0 0%
PAG002 1009 1 1111 199980 0 0 0%
PAG003 100A 1 1111 199980 0 0 0%
------ ------ ----
SUMMARY 599940 0 0%
USABLE 599940 0 0%
Ready; T=0.01/0.01 02:15:41
Normally, this is the pattern that occurs for the backups. The upper
level VM system has higher paging levels. Yesterday, the paging was
occurring on 2nd level production system.
It will be interesting to see what the impact will be when the
production system runs a base VM:Backup backup again.
I greatly appreciate everyone's responses.
Thank you.
Cecelia Dusha
-----Original Message-----
From: Brian Nielsen [mailto:[EMAIL PROTECTED]
Sent: Monday, September 11, 2006 4:10 PM
To: [email protected]
Subject: Re: z/VM 5.1 Paging
Remember that when a user page gets written to a PAGE volume it stays
there until the user logs off. When your page rate was high lots of
user
pages got written to PAGE volumes - thus the high page counts from Q
ALLOC
PAGE. Your page rate dropping low would not reduce the Q ALLOC PAGE
counts. If your page rate later increased again it would not
neccessarily
mean the Q ALLOC PAGE counts would go up even more - it may just mean
you're paging user pages that are already on a PAGE volume. Once a page
is in PAGE space, accessing it frequently doesn't make it take up more
space on your PAGE volumes.
To re-phrase what was said regarding MDC, your page rate may have been
high if too much central storage was in use by MDC. It's all a balance
between how much central storage your logged on users require and how
much
central storage is available to CP to hold those user pages at any
particular moment.
Even with low page rates you may eventually write most user pages to
PAGE
volumes depending on the particulars of when the variouls users are
active
& dormant over long periods of time. So you do need enough PAGE space
to
handle the long term demand for PAGE space, but the amount of PAGE space
is not related to the rate at which you access it. It is related to the
sum of your users virtual memory sizes, the amount of storage available
to
CP, and partly on the activity patterns of the userids.
Brian Nielsen
On Mon, 11 Sep 2006 13:20:15 -0000, Dusha, Cecelia Ms. WHS/ITMD
<[EMAIL PROTECTED]> wrote:
>Are you saying the MDC READS - 142/SEC could be driving the page space
used
>to 55%? The paging rate itself is 1/SEC... We added 2 paging volumes
to
>ensure the system does not run out of paging space.
>
>Our production system is a guest system under z/VM 5.1. I don't know
if
>this would matter in the explanation as to why the system had a 55%
paging
>space utilization...
>
>ind
>AVGPROC-024% 01
>MDC READS-000119/SEC WRITES-000002/SEC HIT RATIO-089%
>STORAGE-047% PAGING-0001/SEC STEAL-000%
>Q0-00001(00000) DORMANT-00120
>Q1-00000(00000) E1-00000(00000)
>Q2-00000(00000) EXPAN-001 E2-00000(00000)
>Q3-00001(00000) EXPAN-001 E3-00000(00000)
>PROC 0000-024%
>LIMITED-00000
>Ready; T=0.01/0.01 09:14:53
>
>q alloc page
> EXTENT EXTENT TOTAL PAGES HIGH %
>VOLID RDEV START END PAGES IN USE PAGE USED
>------ ---- ---------- ---------- ------ ------ ------ ----
>510PAG F005 1 3338 600840 333053 443499 55%
>PAG002 F008 1 3337 600660 0 0 0%
>PAG003 F00A 1 3337 600660 0 0 0%
> ------ ------ ----
>SUMMARY 1760K 333053 18%
>USABLE 1760K 333053 18%
>Ready; T=0.01/0.01 09:15:12
>
>Thank you.
>
>Cecelia Dusha
>-----Original Message-----
>From: Jim Bohnsack [mailto:[EMAIL PROTECTED]
>Sent: Monday, September 11, 2006 9:01 AM
>To: [email protected]
>Subject: Re: z/VM 5.1 Paging
>
>Paging rate and page occupancy are not directly related. Do you have
an
>earlier number for page occupancy? 55% utilization may just be what is
>required in a normal, steady state.
>Jim
>
>At 07:57 AM 9/11/2006, you wrote:
>>Our production system was migrated from z/VM 3.1 to z/VM 5.1 over the
>>weekend.
>>
>>The paging rate was high this morning on the production system as the
>>VM:Backup backups were running. (It was paging over 2000 pages per
>second.)
>>When I did a Q ALLOC PAGE, it indicated the percentage used was 55%.
>>
>>Presently (the backups have completed):
>>ind
>>AVGPROC-015% 01
>>MDC READS-000142/SEC WRITES-000003/SEC HIT RATIO-093%
>>STORAGE-000% PAGING-0001/SEC STEAL-000%
>>Q0-00001(00000) DORMANT-00077
>>Q1-00001(00000) E1-00000(00000)
>>Q2-00000(00000) EXPAN-001 E2-00000(00000)
>>Q3-00000(00000) EXPAN-001 E3-00000(00000)
>>PROC 0000-015%
>>LIMITED-00000
>>Ready; T=0.01/0.01 07:42:42
>>
>>q alloc page
>> EXTENT EXTENT TOTAL PAGES HIGH %
>>VOLID RDEV START END PAGES IN USE PAGE USED
>>------ ---- ---------- ---------- ------ ------ ------ ----
>>510PAG F005 1 3338 600840 334304 443511 55%
>> ------ ------ ----
>>SUMMARY 600840 334304 55%
>>USABLE 600840 334304 55%
>>Ready; T=0.01/0.01 07:43:04
>>
>>Being the system utilization is still low, I am a bit apprehensive as
to
>>what will occur when the system gets busy through the day...
Shouldn't
the
>>Q ALLOC PAGE percentage used have dropped?
>>
>>Thank you.
>>
>>Cecelia Dusha
>
>Jim Bohnsack
>Cornell Univ.
>(607) 255-1760
>=======================================================================
==
