How is the page size of rootdbs determined?

[Desmodromic]

I have an IDS instance running 11.50.FC4 on AIX. The OS pagesize is as follows:

$ pagesize
4096

The rootdbs page size is also 4096 bytes as shown below:

Dbspaces
address number flags fchunk nchunks pgsize flags owner name
700000071953028 1 0x40001 1 1 4096 N B informix root

On a server running Ubuntu 8.04.4 LTS I initialized an IDS instance also using 11.50.FC4.

The Ubuntu pagesize is also 4096 bytes:

$ getconf PAGESIZE
4096

However, the rootdbs has a page size of 2048 bytes:

Dbspaces
address number flags fchunk nchunks pgsize flags owner name
4e04d028 1 0x40001 1 1 2048 N B informix rootdbs

Can anyone tell me:-

1. How the default page size of the rootdbs is determined?
2. Whether it is possible to specify the page size for the rootdbs?

Many thanks.

[jrenaut]

1) The instance's default page size is determined at source code compile time and I believe it is 2Kb for all unix platform but AIX which uses 4Kb.

2) You can not change the page size of the root dbspace. Also from a quick look in the documentation, logical logs and the physical log need to be in default page sized dbspaces.

Jacques Renaut
IBM Informix Advanced Support
APD Team