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swap file 1

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rms4

Technical User
Dec 1, 2000
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AU
how can i create a swap file?

 
1. smit lvm
2. click on paging space.
3. click on add another paging space
4. select a volume group from the list where u have free
space.
5. enter the size of paging space in logical partitions.
here check on your PP size for that volume group and
decide on how much swap space you need and devide the
swap size by the pp size to get the number of logical
partitions. enter this value.
6. enter the physical volume that holds that many free
partitions.
7. start using the paging spacve now say yes
8. if u want the paging space activated at system restart
too then say yes to that too
9 check ur paging space by running lsps -a


Hope this helps,
sendhil

 
FWIW, AIX does not swap programs out, it pages them in/out. It's a small difference, but if you have a really large program it is quite possible that only the part of it being used will be in memory. The rest will remain on disk until called for. When that process has used up it's timeslice and needs to give back some memory, the least recently used pages are paged out, the program is not wholesale "swapped" out and swapped back in when it's time to run again. It's a little more efficient this way.

Also, pages do not get paged out until the memory is needed. I have seen many systems that have 100% memory utilization and the sys admins are worried. However, since there was no paging activity there is not a performance problem. AIX will clean up old pages when it needs to, not before, so don't necessarily use memory utilization as a performance monitor.

Be sure to check the utilization of your paging space using the lsps -a command. This will show you your paging spaces and utilization. I have often seen systems with lots of memory using only 5-10% of it's page space. Don't add page spaces if you don't need them. Spreading page spaces on multilple disks may help performance, but only if your system is paging. Check out the vmstat command for paging statistics.

With AIX you should have as much page space as you have memory. (2GB of memory, you need at least 2GB of page space). If you have less memory you may need page space equal to 2x or 3x memory.

And if you need more, follow the excellent directions above.

Good luck.
 
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