optimum size of paging space for added RAM

optimum size of paging space for added RAM

Post by P.M.Won » Fri, 04 Dec 1998 04:00:00



Our RS6K has been running smoothly with 320Mb memory (the primary
paging space as recommended when AIX 4.2.1 was installed is 352Mb)
We are going to run more memory intensive apps on the machine, so we'll
install 256Mb more RAM. Now could someone suggest the optimum size  
of the extra paging space (assuming we add one more paging only)
to add for this amount of extra memory (Since we'll not install the
OS again, so i wouldn't be able to have the OS calculate a good value
for me like the last time we have 4.2.1 freshly installed)

        __

  /      ( -------------  }  System Support Programmer,
 (  =l=ll===============__}  Computing & Telecomm. Services Centre
  \   _  (                   Hong Kong Baptist University
   \_/ \__)                  224 Waterloo Road, Hong Kong  

 
 
 

optimum size of paging space for added RAM

Post by Louis Fege » Fri, 04 Dec 1998 04:00:00


General rule of thumb... pageing space should be 1-to-2 times the size
of real memory.

\louis


> Our RS6K has been running smoothly with 320Mb memory (the primary
> paging space as recommended when AIX 4.2.1 was installed is 352Mb)
> We are going to run more memory intensive apps on the machine, so we'll
> install 256Mb more RAM. Now could someone suggest the optimum size
> of the extra paging space (assuming we add one more paging only)
> to add for this amount of extra memory (Since we'll not install the
> OS again, so i wouldn't be able to have the OS calculate a good value
> for me like the last time we have 4.2.1 freshly installed)

>         __

>   /      ( -------------  }  System Support Programmer,
>  (  =l=ll===============__}  Computing & Telecomm. Services Centre
>   \   _  (                   Hong Kong Baptist University
>    \_/ \__)                  224 Waterloo Road, Hong Kong


 
 
 

optimum size of paging space for added RAM

Post by si.. » Fri, 04 Dec 1998 04:00:00



> The important thing is to use multiple paging spaces of similar size on
> different disks. If you are going to run more memory intensive applications
> I would add another paging space of 300 (or 352) MB and see what
> happens. If you are going to have many smaller paging spaces on many disks,
> you have to reduce the size of hd6 (the primary paging space), which
> requires special treatment.

What he said.  Make it 352, and put it on a seperate, but hopefully
not heavily used, disk
--

Simon Travaglia,  Email without auto spam rejection at by removing the


http://mrjolly.cc.waikato.ac.nz Ph: +64 7 838-4709 Fax: +64 7 838-4066
  University of Waikato, Private Bag 3105, Hamilton, New Zealand..

 
 
 

optimum size of paging space for added RAM

Post by Robert Kenned » Fri, 04 Dec 1998 04:00:00





> > Our RS6K has been running smoothly with 320Mb memory (the primary
> > paging space as recommended when AIX 4.2.1 was installed is 352Mb)
> > We are going to run more memory intensive apps on the machine, so we'll
> > install 256Mb more RAM. Now could someone suggest the optimum size
> > of the extra paging space (assuming we add one more paging only)
> > to add for this amount of extra memory (Since we'll not install the
> > OS again, so i wouldn't be able to have the OS calculate a good value
> > for me like the last time we have 4.2.1 freshly installed)

> Approximate calculation for paging space requirement is RAM + 16 MB,
> but you might need more paging space depending on the type of applications
> you're using. Databases usually need more.

> The important thing is to use multiple paging spaces of similar size on
> different disks. If you are going to run more memory intensive applications
> I would add another paging space of 300 (or 352) MB and see what
> happens. If you are going to have many smaller paging spaces on many disks,
> you have to reduce the size of hd6 (the primary paging space), which
> requires special treatment.

Whoa!  He shouldn't necessarily add separate paging spaces on different disks.
It really depends on what his machine does.  This could*his performance
all up with added disk I/O.  If it's a database machine, he'll be done for.  If
not, it should work okay, but adding more paging spaces 'willy-nilly' is just a
bad idea.  It should be planned accordingly.  He may only need to increase the
existing paging space.  Also, the "rule-o-thumb" for paging spaces is:

        total paging space = 512MB + (memory size - 256MB) * 1.25

Separate paging spaces should be of equal size, if possible, for the
round-robin algorithm.  The primary paging space can be a bit larger, though,
with no ill effects.  In fact, it should be a scosh larger for booting
purposes.

HTH

Rob
--
Robert Kennedy  -  These foolish ideas are all my own.
Boeing Space and Defense Group
Kent Space Center
System Administration - CAD/CAM

Small minds discuss people;
Average minds discuss events;
Great minds discuss ideas.

 
 
 

optimum size of paging space for added RAM

Post by Maik Tom » Sat, 05 Dec 1998 04:00:00


...
Quote:> Whoa!  He shouldn't necessarily add separate paging spaces on different disks.
> It really depends on what his machine does.  This could*his performance
> all up with added disk I/O.  If it's a database machine, he'll be done for.  If
> not, it should work okay, but adding more paging spaces 'willy-nilly' is just a
> bad idea.  It should be planned accordingly.  He may only need to increase the
> existing paging space.  Also, the "rule-o-thumb" for paging spaces is:

>         total paging space = 512MB + (memory size - 256MB) * 1.25

> Separate paging spaces should be of equal size, if possible, for the
> round-robin algorithm.  The primary paging space can be a bit larger, though,
> with no ill effects.  In fact, it should be a scosh larger for booting
> purposes.

...

I agree.

From my point of view a good rule is

if MEMSIZE <= 64M then PAGSPACE=2xMEMSIZE
if MEMSIZE <= 256M then PAGSPACE=MEMSIZE+16M
if MEMSIZE > 256M then PAGSPACE=512M+(MEMSIZE-256)x1.25

HTH, Maik.

 
 
 

1. Optimum Paging Space Size

Hi there

What is the optimum size of paging space on a machine which has
10 GB RAM. In performance tuning book IBM recommends the maximum
size of paging space with a formula. But I dont think that for
this RAM size it will work.

What I usually do is to make paging space nearly twice the size
of RAM, but I dont think that I require this much amount of
paging space over here. So what the best thing to do over here?

Your comments/advice are deeply appreciated.

Regards

Salman

* Sent from RemarQ http://www.remarq.com The Internet's Discussion Network *
The fastest and easiest way to search and participate in Usenet - Free!

2. how to access win files over network

3. Paging space size (NOT swap space size)

4. Mode Lines for Twinhead Slimnote VX

5. adding paging space

6. Anybody using netatalk?

7. Real size in Bytes of a process paging space

8. Router interface to Linux

9. Paging space sizes...

10. Reducing the size of the primary paging space

11. paging space size for Oracle database server?

12. Size of Paging Space?

13. optimum space for different partions..