From: Martin W. Johnson (fclmwj@NERSP.NERDC.UFL.EDU)
Date: Tue Jul 23 2002 - 17:28:34 EDT
This is from AIX 4.3 Base Documentation Performance Tuning Guide:
"Ideally, there should be several paging spaces of roughly equal size,
each on a different physical disk drive. If you decide to create
additional paging spaces, create them on physical volumes that are more
lightly loaded than the physical volume in rootvg. When allocating
paging space blocks, the VMM allocates four blocks, in round-robin
fashion, from each of the active paging spaces that has space
available. While the system is booting, only the primary paging space
(hd6) is active. Consequently, all paging-space blocks allocated during
boot are on the primary paging space. This means that the primary
paging space should be somewhat larger than the secondary paging
spaces. The secondary paging spaces should all be of the same size to
ensure that the round-robin algorithm can work effectively."
I take this to mean that the OS will try each paging space until it
finds one that has space. When some are full, and some are not, that's
inefficient, but it will try its best.
On Tue, 23 Jul 2002 15:09:33 -0500 Bill Verzal <Bill_Verzal@BCBSIL.COM>
wrote:
> I am assisting a DBA with troubleshooting a system (SP node, AIX
4.3.3 ML
> 10). I wish to make a statement to management, but I want to confirm
it
> first...
>
> Can anyone confirm the following statement for me (and provide
resources) ?
>
> "If you have a system with more than one paging space, and they
happen to
> be different sizes, the system will not use any of the larger paging
> space(es) beyond the size of the smaller"
>
> For example
>
> System A has 3 paging spaces configured as follows:
>
> 1024MB
> 512MB
> 2048MB
>
> AIX will not use more than 512MB of ANY of the paging spaces.
>
> Is this true ? I recall that it is (or was at one time).
>
> Thanks!
>
>
>
-----------------------------------------------------------------------------------------------------------
>
> Bill Verzal
> Technical Consultant
> Forbes Technical Consulting
> (312) 653-3684
> bill_verzal@bcbsil.com
> MailStop: 27.201C
------------------------
Martin W. Johnson
Coordinator, Computer Applications
Florida Center for Library Automation
2002 N.W. 13 Street, Suite 320
Gainesville, FL 32609
(352) 392-9020 Fax: (352) 392-9185
fclmwj@nersp.nerdc.ufl.edu
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