How to free / clean up paging space ?

[TSch]

Good Morning everybody,

we're using SAP Release 4.6C on Basis 4.6D for our R/3, and 620 for our BW Systems together with IBM DB2 V8.1.7b / V8.2 under AIX 5.2 ML4 and ML5.

Problem is that quite often more than 40% of our paging space are consumed by SAP (you can see that via topas).

So far so good. Fact is there are some jobs on R/3 that are using a lot of memory (more than we have, so that the system has to start paging). But after those jobs are finished and the system becomes idle (almost no CPU load, almost no disk activity, no jobs running) the paging space remains at over 40% use and it takes a lot of time for at least a little bit of it to become free again. Although all the resources are free and the system should have more than enough opportunity to free paging space.

Only way to clean it up completely is to perform a stopdb, which than takes quite some time to complete because it has to write all the data in the paging space back to the disks.

Is there any way to speed up the "normal" process of cleaning up paging space under running (!) system as soon as there are enough free resources under AIX without having to do a stopdb ? You can understand, that we'd like to keep the system up and running

Thanks in advance !

 

[apb99]

when you say paging space is being used is this just the % Used %Free figures in topas or are you looking at PgspIn and PgspOut,

PgspIn and PgspOut indicate true paging the % used incorporates the file disk paging used, this is normal with disk reads, the PgspIn PgspOut figures are actual memory paging, if these remain at 0 then you don't have a paging issue

 

[TSch]

Hi,

it's the % Used value ...
Is there any way to decrease this value while SAP System as well as DB are up and running ?
Problem is that it takes a lot of time for stopsap to complete whenever the % used value is quite high (about 50%) ...

Regards
Thomas

 

[apb99]

Hi

not sure why the issue if you are not seeing any paging in PgspIn and PgspOut then it is not a memory problem the disk i/o is paged in aix, so is caused by high disk i/o as in when reading and writing to the database, ours currently runs at 80-85% used and is not a problem