Re: AIX Memory and Paging Space
From: hercom (hercom_at_ETB.NET.CO)
Date: 05/13/05
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Date: Thu, 12 May 2005 23:44:58 -0500 To: aix-l@Princeton.EDU
AIX will always try to use 100% of real memory--> AIX will use the amount of
memory solicited by your processes. The remaining capacity will be used as
filesystem cache.
You can change the minimum and maximum amounts of memory used to cache files
with vmtune (vmo for 5.2+), and it is advised to do so if your’re running
databases with data on raw devices (since the db engine usually has its own
cache algorithm, and AIX can’t cache data on raw devices). The values to
modify are minperm, maxperm, minclient and maxpin (use at you own risk!!!).
Paging space use will be very low: 5% is about right--> A paging space so
little used seems to be oversized. In general, the paging space should be
under 40%, and the size must be determined accordingly to the application
running (i.e. 4X the physical memory size for oracle). In AIX 5L a paging
space can be reduced without rebooting. Anyway, AIX always uses some paging
space, even keeping copies of the data on memory and on disk, as a
“predictive” paging.
Look in topas for the values “comp mem” (proceses) and “non comp mem”
(filesystem cache) to see the distribution of the memory usage. Nmon can
show you the top proceses by memory usage, along with many other statistics.
Hernán Camargo
RS6K
232
SISA S.A.
_____
From: IBM AIX Discussion List [mailto:aix-l@Princeton.EDU] On Behalf Of
Green, Simon
Sent: Wednesday, May 04, 2005 4:06 AM
To: aix-l@Princeton.EDU
Subject: Re: AIX Memory and Paging Space
AIX will always try to use 100% of real memory, (apart from a very small
amount left unused for sudden demands). If you've got enough memory, paging
space use will be very low: 5% is about right, allowing for the overheads of
LVM and a small amount of paging space use after a boot.
There are several tools which can give you a more detailed picture of how
memory is being used. "svmon" is very comprehensive. Tools such as topas
and nmon will also give you a bit more information.
-- Simon Green Altria ITSC Europe s.a.r.l. AIX-L Archive at https://new-lists.princeton.edu/listserv/aix-l.html New to AIX? http://publib-b.boulder.ibm.com/redbooks.nsf/portals/UNIX N.B. Unsolicited email from vendors will not be appreciated. Please post all follow-ups to the list. -----Original Message----- From: IBM AIX Discussion List [mailto:aix-l@Princeton.EDU] On Behalf Of Akash Jain Sent: 04 May 2005 07:00 To: aix-l@Princeton.EDU Subject: AIX Memory and Paging Space Hi, Is it correct to say that AIX server is running on full 100% utilisation and memory usage is below 5%( paging space). What does this mean? Please explain if any one has any idea about it. Is there anyway of monitoring actual memory utilisation without paging space.
- Previous message: Alexandre Sato: "Re: LAN Adapter Media Speed Selection"
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