Originally posted by: SystemAdmin

Hi
My server once utilize paging space, does not release it even no application is running. I created another paging device and swapoff earlier one and when complete page is released, swapon again. In this process, newly created page also does not increase at the time of swapoff of old page that shows no process needed swap.

Please highlight some thoughts.

Regards
Amit Bist
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Originally posted by: SystemAdmin

Also, disk i/o where that paging device resides goes to 100% in between. But after the paging is released it decends to 1%
All vmo parameters are tunedperfectly.
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Originally posted by: drajarsh

>>Also, disk i/o where that paging device resides goes to 100% in between. But after the paging is released it decends to 1%
All vmo parameters are tunedperfectly.

I think when the paging device is getting released (as a result of swapoff), it is trying to free up all the data that it might have relating to older applications that it had serviced (probably cached data) and writes that data back to disk, which is why the disk IO might be going to 100%.

Please correct me if I am wrong in my assumption here.

Thanks.
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Originally posted by: SystemAdmin

No, its not correct. If server uses paging space in aniticipation of future use, it would have used complete pagespace. And whats the use of VMM which allocates and deallocates page spaces according to the usage?
Regards
Amit Bist
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Originally posted by: SystemAdmin

I have found something related to this issue,

http://www-01.ibm.com/support/docview.wss?uid=isg1IZ09761
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Originally posted by: drajarsh

The paging space can not be released by the server since it is maintained in anticipation of future applications that can be started. The paging space would need to be explicitly freed up but that again would be allowed only if there are sufficient other paging devices on the system.

Folks: I am a newbie, please correct me if the above is incorrect.

Thanks
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Originally posted by: drajarsh

>>In this process, newly created page also does not increase at the time of swapoff of old page that shows no process needed swap.

Regarding the above query, when the swapoff happens, all it does is to release the first paging device so that no more pages can be allocated from that device for future/ existing apps. This also means that the pages that can be allocated can now come only from the second paging device (which has already happened for our app due to the swapon command) hence the newly created page size would not increase.

Please correct me if I am wrong in stating the above.

Thanks.
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