Re: AIX Memory and Paging Space
Date: Fri, 13 May 2005 12:33:03 +0200 To: aix-l@Princeton.EDU
just one advantage and one disadvantage of a big "oversized" ps
disadvantage: (cheap) diskspace wasted
advantage: more time to react if an application starts to use much
f.e. I prefer to have 4GB ps and get a warning when its 50% full (2gb
used) than to have 2GB and get a warning when its 99/100% full
>AIX will use the amount of memory solicited by your processes
in rare cases processes demand real memory, they request the os to pin
it (plock()). then, this statement is true for those processes.
in all other cases processes demand only virtual memory and aix is free
to put it in real mem or paging-space
From: IBM AIX Discussion List [mailto:aix-l@Princeton.EDU] On Behalf Of
Sent: Friday, May 13, 2005 12:13 PM
Subject: Re: AIX Memory and Paging Space
It's not possible to say that the paging space is oversized from the
information available. If you allocate the minimum permitted paging
space - required for the system to boot - but do no paging at all it
will appear about 5% used. That's due to the LVM overhead and a small
amount of data that goes in there at boot time.
If the %used was 1% I might guess it was oversized; otherwise you'd have
to know what the size really was. The original post does not suggest
that this is the case.
-- 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 hercom Sent: 13 May 2005 05:45 To: aix-l@Princeton.EDU Subject: Re: AIX Memory and Paging Space 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.