That is a rough calculation and seems to be more appropriate for z/Linux
only environments. In a CMS heavy environment it can be much less
because of DCSS usage and over allocation of Virtual Storage.
On our CMS heavy system, the calculation is:
qvirstor
Total Virtual Storage = 41735M ~ 40.7G
Needs 13 3390-3 TOTAL PAGE DASD
We have 10G Storage and 2G Expanded and have no paging:
q store
STORAGE = 10G
q xstore map
START SIZE STATUS %-IN-USE %-UNUSABLE
0M 2048M CP(RETAINED) 0% 0%
Ready; T=0.01/0.01 10:24:51
q alloc page
EXTENT EXTENT TOTAL PAGES HIGH %
VOLID RDEV START END PAGES IN USE PAGE USED
------ ---- ---------- ---------- ------ ------ ------ ----
VMPAG1 AE97 1 3338 600840 0 0 0%
VMPAG2 AF07 1 3338 600840 0 0 0%
VMPAG3 AF18 1 3338 600840 0 0 0%
VMPAG4 AF2B 1 3338 600840 0 0 0%
VMPAG5 AF8E 1 3338 600840 0 0 0%
------ ------ ----
SUMMARY 2934K 0 0%
USABLE 2934K 0 0%
-----Original Message-----
From: The IBM z/VM Operating System [mailto:[EMAIL PROTECTED] On
Behalf Of Huegel, Thomas
Sent: Wednesday, December 12, 2007 10:19 AM
To: [email protected]
Subject: Performance ? How much page area to allocate?
IBM publishes a formula for calculating how much page space to
allocate.
The formula is something like this: (Total amount of logged on
user storage - amount of REAL memory) x 2 = the amount of storage to map
to DASD.
When I do this calculation I come up with a requirement of 10
3390 mod3 for my page space.
I only have 2 3390 mod3's for page and I don't seem to be having
any problems.
The question is 'am I missing something'?
My page rate is < 2/sec.
The only thing I ever see is occasionally LINUX will slow down
for a second or two.
Any thoughts or comments would be appreciated.
Thanks
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