[cdelgadop]

HI

Looks like hd6 paging space (that is the default) has been erased. You server has too much paging space defined. Some applications like SAP and Oracle requires such amount of PS, anyway, when %used is greather than 30% I/O performance problems starts to happen.

You need to apply some tuning to your PS devices.

First, how much RAM does your server has?. The most basic rule of thumb is PS=2xRAM. If this value is ok with your appl requirements then apply this value.

Second, it's not recommended to have multiple PS of different sizes. Then you need to make all those pagingXX devices roughly the same size.

Third, you need to apply some tuning to the Virtual Memory Manager of AIX (VMM), what AIX versiona re you running?, if AIX 5L you can use the vmo command in order to review and chage some parameters you can use to avoid double buffering that's is the case when running Orcale/DB2 on JFS2 FS. Please read man vmo and post the output of the folllwing command:

vmo -a | egrep "maxperm|minperm|maxclient"

these parameters below controls the behavior of the PS.

Hope this helps

[alexisl]

We have about 19 GB of RAM and only about 28 GB of paging, we were going by a rule of 1.5 times the RAM.

We are on 5.3 ML4

vmo -a | egrep "maxperm|minperm|maxclient"
maxclient% = 80
maxperm = 3887837
maxperm% = 80
minperm = 971956
minperm% = 20
strict_maxclient = 1
strict_maxperm = 0

[cdelgadop]

Hi

I would change the following values:

maxclient% = 8
maxperm% = 8
minperm% = 3

and test the behavior of the server.

With 19GB RAM i would use up to 20GB Paging Space splitted on two Volume groups (rootvg with 10 GB) and another VG, say Swapvg, with 10 GB, and only if the appl requierements told me to use such a big ammount of PS.

The idea is to use up to 25% of PS activity. If you use more than that you need to tune your SO, appls or even the DB.

AIX 5L Initial Tuning

Hope this helps

[alexisl]

There is no doubt in my mind that the DB needs tuning, we didn't have this problem until we moved from 9i to 10g. I am not a DBA so I really don't know how to do anything with Oracle.

As far as changing the percentages, what is the potenial of slowing down the system even more? Are the settings I already have the default settings?

I guess I already have enough paging space but how do I change it to even it out? My paging00 space is spread unevenly on two seperate drives so how can I fix this?

[AIX_Dude]

a thought with AIX and oracle, look at the log writers and db writer processes. I used to run a set of p650's that swallowed 12+gb of swap every week and 1/2 required an IPL to recover.

[AIX_Dude]

also with IBM's VMM the 1.5 or 2x paging to real, doesn't really apply. the VMM is very good at releasing memory. hence a process called LRUD