From: Hunter, Mark (Mark.Hunter@ANHEUSER-BUSCH.COM)
Date: Wed Jan 14 2004 - 12:33:04 EST
Here is what we saw and why. Note IBM and oracle both recommend setting vmtune
minperm/maxperm way down on oracle servers.
Oracle allocates a huge SGA (shared memory). This is not backed by paging space
initially. Typically, the Oracle team wants about 60% of the box for
themselves.
Oracle puts stuff into the SGA. No paging space yet.
Time passes. Files get touched. IBM's caching algorthm + shared memory +
processes eat up all the real memory. No paging space yet.
More memory is requested. IBM's paging algorithm kicks in. The oracle SGA has
hot areas, and a bunch of stuff that almost never gets touched. The little used
areas of this shared memory get paged out to allow room for more file caching.
Lots of paging space now if minperm/maxperm are too large.
The paging space around the oracle SGA only gets released when the last process
stops touching it. Thus the reboot/restart clears paging space for a bit.
Note: Once you change min/max perm, you have to cycle the database to get the
space back since once allocated, paging space normally only gets unallocated
when the last process accessing it is gone.
Mark Hunter
-----Original Message-----
From: jbarratt [mailto:jbarratt@COMPSAT.COM]
Sent: Wednesday, January 14, 2004 11:20 AM
To: aix-l@Princeton.EDU
Subject: Re: Paging space on a fastT
It seems to me that since you can turn on and off paging spaces on the
fly, and that deferred paging space algorithms don't take more than
necessary. that you would just add as needed (that's what I have always
done)..however, don't come crying to SAP when paging space hits 100% and
you are unable to open a terminal session to add more...you will
probably be recycling the power.
Just my 2 cents
-----Original Message-----
From: IBM AIX Discussion List [mailto:aix-l@Princeton.EDU] On Behalf Of
Wilson, Jeff
Sent: Wednesday, January 14, 2004 12:09 PM
To: aix-l@Princeton.EDU
Subject: Re: Paging space on a fastT
We are running 5.1 . I am going to try and talk them into changing the
min and maxperms first and see how that helps. We mostly see the paging
space get lower and lower over time. We start out with 98% free and
over a couple of months it gets down to 60-70% free.
Jeff Wilson
303-737-5399
-----Original Message-----
From: Bob.Kelley@BRINKSINC.COM [mailto:Bob.Kelley@BRINKSINC.COM]
Sent: Wednesday, January 14, 2004 9:52 AM
To: aix-l@Princeton.EDU
Subject: Re: Paging space on a fastT
Version of AIX?
Reason for this is with aix 5 you now have whats commonly referred to
defferred paging. This essentially is the allocation of paging space
when it's needed, rather than in previous versions of aix 4.3.2 and
below I believe where exe's would allocate paging space as large as
their running image even if it turned out they never used it. This is
one of the reasons Simon points out that its no longer necessary to
adhere to vendors software requirements for paging space in certain
cases bc its really solution dependent.
Bobby Kelley Jr.
972-877-5341
|---------+-------------------------------->
| | "Hunter, Mark" |
| | <Mark.Hunter@ANHEUSER|
| | -BUSCH.COM> |
| | Sent by: IBM AIX |
| | Discussion List |
| | <aix-l@Princeton.EDU>|
| | |
| | |
| | 01/14/2004 10:29 AM |
| | Please respond to IBM|
| | AIX Discussion List |
| | |
|---------+-------------------------------->
>-----------------------------------------------------------------------
------------------------------------------------------------------------
---|
|
|
| To: aix-l@Princeton.EDU
|
| cc:
|
| Subject: Re: Paging space on a fastT
|
>-----------------------------------------------------------------------
------------------------------------------------------------------------
---|
We run SAP on Oracle.
We set minperm to 5% and maxperm to 20%. Helps alot.
Our SAP team wants 3x memory for paging also. We ignore this and give
them 1x. With minperm/maxperm set, they use very little paging space.
Mark Hunter
-----Original Message-----
From: Bob.Kelley@BRINKSINC.COM [mailto:Bob.Kelley@BRINKSINC.COM]
Sent: Wednesday, January 14, 2004 10:21 AM
To: aix-l@Princeton.EDU
Subject: Re: Paging space on a fastT
what version of aix are you running? check your vmtune settings and post
pls
Bobby Kelley Jr.
972-877-5341
|---------+---------------------------->
| | "Wilson, Jeff" |
| | <Jeff.Wilson@GWL.|
| | COM> |
| | Sent by: IBM AIX |
| | Discussion List |
| | <aix-l@Princeton.|
| | EDU> |
| | |
| | |
| | 01/14/2004 09:59 |
| | AM |
| | Please respond to|
| | IBM AIX |
| | Discussion List |
| | |
|---------+---------------------------->
>
------------------------------------------------------------------------
-------
-------------------------------------------------------------------|
|
|
| To: aix-l@Princeton.EDU
|
| cc:
|
| Subject: Re: Paging space on a fastT
|
>
------------------------------------------------------------------------
-------
-------------------------------------------------------------------|
We are running the paging monster app "SAP on DB2". I have never seen
an app eat paging space like this one. If we bounce SAP we get it all
back but until we do that SAP keeps all the paging space and dose not
release it. As always the recommend 2 X physical memory but with the
new SAP installs they want 3 X physical memory which is ridicules but I
have no choice in the matter so I have to add it even if they don't need
it.
Jeff Wilson
303-737-5399
-----Original Message-----
From: JOSEPH KREMBLAS [mailto:jkremblas@REDHEARTGIFTS.COM]
Sent: Wednesday, January 14, 2004 8:34 AM
To: aix-l@Princeton.EDU
Subject: Re: Paging space on a fastT
Jeff,
Before throwing more paging space at the system, have you ran
vmstat and iostat to see what the system is doing? Can you provide
a
vmstat listing and iostat listing? Are you running Oracle? Any
other
databases? Also, provide the output of vmtune and schedtune. The
group may be able to tell what's going on performance wise and
make
some recommedations.
--joseph
-----Original Message-----
From: IBM AIX Discussion List [mailto:aix-l@Princeton.EDU] On
Behalf
Of Wilson, Jeff
Sent: Wednesday, January 14, 2004 8:27 AM
To: aix-l@Princeton.EDU
Subject: Paging space on a fastT
I was wondering if anyone has had any experience putting paging
space
on attached disks like a fastT 900. I am out of space on my
internal
OS disks and need more paging space and was wondering if there are
any problems I should be aware of before I do this. Thanks for
you
help.
Jeff Wilson
System Administrator
Great-West Life & Annuity Ins. Co.
Desk: (303) 737-5399
NOTICE TO BRINK'S EMPLOYEES:
All electronic mail communications composed, sent, received or stored on
or through Brink's equipment are subject to the Brink's Electronic
Communications Policy. Employees should have no expectation of privacy
in their use of the Company's electronic mail system
NOTICE TO BRINK'S EMPLOYEES:
All electronic mail communications composed, sent, received or stored on
or through Brink's equipment are subject to the Brink's Electronic
Communications Policy. Employees should have no expectation of privacy
in their use of the Company's electronic mail system.
This archive was generated by hypermail 2.1.7 : Wed Apr 09 2008 - 22:17:30 EDT