Re: Exact steps to change DB_BLOCK_SIZE

In article <8l4ddu$mff$1_at_nnrp1.deja.com>,   vasarpota_at_my-deja.com wrote:
> Does anyone know the exact procedure (if there is a white paper) to
> resize the Oracle Block Size. And what considerations should be taken
> (e.g. larger data buffer, etc)
>
> Thanks for your help
>
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> Before you buy.
>

The only way to reset the DB_BLOCK_SIZE is to recreate the database. As the most common db_block_size values are powers of 2 (2K, 4K, 8K, 16K, 32K, etc.) dividing the db_block_buffers value by (new DB_BLOCK_SIZE / old DB_BLOCK_SIZE) is the usual adjustment. For example, if you are running with a 2K block size and a db_block_buffers value of 20000 and you increase the db_block_size to 8k the db_block_buffers value would be adjusted to 5000 -- 20000/(8/2) == 20000/4 == 5000. Also the db_file_multiblock_read_count value should be adjusted by the same factor. If this value is 16 for a 2K block size then the 8k block size would require this to be reduced to 4 (16/4 == 4). Should this be set you will also need to adjust the db_file_direct_io_count value.

I would have a reliable export of the current instance before beginning this task since all datafiles will need to be removed and recreated.

--
David Fitzjarrell
Oracle Certified DBA


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