This enhancement has not been implemented in the product to date (2020/11/01).
When the aiblocksize is not the same size as the before-image blocksize:
- This can yield unexpected consequences should after-imaging need to be disabled then re-enabled online at sometime in the future.
- This means that if the aiblocksize = 16 (initially changed offline truncate aiblocksize and the before-image blocksize is smaller eg biblocksize = 8), the aiblocksize will be re-set equal to the biblocksize (8 KB) for performance reasons when subsequently enabling AI online (probkup online enableai).
- Another use-case is when the aiblocksize is changed when initially enabling after-imaging. At sometime in the future, ai is disabled offline (aioff) followed by online enableai enableaiarchiver
- Having the AI blocksize <> BI Blocksize is a performant hit. In essence, if the AI block half the BI block
As soon as an AI block needs to be flushed off the aibufs queue, the database manager must first flush the BI Block with the associated notes and the DB blocks. Therefore, BI blocks can be flushed sooner that are not being filled.
To resolve the AI and BI Blocksizes:Before enabling AI online, ensure the biblocksize is the size required for the aiblocksize or it will be changed when you enable online (or disable and enable online as the case may be).
Changing the bi blocksize is an offline operation and changing the AI blocksize requires After-Imaging to be disabled:In order to change the
aiblocksize, after-imaging (and all it's dependent features viz: AIMGT and OER) must first be disabled.
$ rfutil <dbname> -C aimage end
Once disabled, (optionally the BI blocksize) the AI blocksize can be changed:
$ proutil <dbname> -C truncate bi -G 0 -biblocksize 16
$ rfutil <dbname> -C aimage truncate -aiblocksize 16
Re-enable After-Imaging (and site-specific dependencies):
$ rfutil <dbname> -C mark backedup
$ rfutil <dbname> -C aimage begin -G 0
$ rfutil <dbname> -C aiarchiver enable
$ proutil <dbname> -C enablesitereplication source
For further information refer to Article
How to change the after-image block size 
