How to calculate PP size in aix?
If you dont specify the PP size during the creation of volume group, AIX will take default size. However we can identify the PP size within a second once we understand the concept.
In aix, the pp size is calculating based on the size of the disks. AIX can use the specific numbers as the PP size. and the pp size is the constant one.. which means it should be in any one of the below numbers.
1, 2, 4, 8, 16, 32, 64,128,512,1024, (MB).
If the disk size is exactly 2 then the PP size would be 2MB
If the disk size is exactly 4 then the PP size would be 4MB
If the disk size is exactly 8 then the PP size would be 8MB
.like wise we can get to know if the disk size is exactly 16,32,64,128,256,512,1024 GB then the pp size is 16MB, 32MB, 64MB, 128MB, 256MB, 512MB, 1024MB respectively.
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If the disk size is between 4GB < 8GB then the pp size is 8MB (Greater than 4 GB & less than 8GB)
If the disk size is between 8GB < 16GB then the pp size is 16MB.(Greater than 8 GB & less than 16GB)
Please see the below diagram for the rest of the disk size and its pp size.
if the disk size is 20 GB then what would be the pp size?
The disk size is 20GB which lies between 16GB - 32GB, so the pp size is 32MB.
(The pp size should not be 16MB as the disk size is more than 16GB, so the next PP size is 32, so the system would take 32MB)
Now i am going to ask you one questioin... If the disk size is 132 GB, tell me what is the pp size?
Yes, you are correct, the pp size is 256 MB.
Note: Always remember the pp size should be any one of the below numbers for normal & big vg.
1,2,4,8,16,32,64,128,256,1024.
| Original and Big Volume Groups | |
|---|---|
| hdisk size between: | Default PP Size |
| Scalable Volume Groups | |
|---|---|
| hdisk size between: | Default PP Size |
