Re: O_DIRECT in freebsd

My experience with DB2 showed that properly setup DMS tablespaces provided a
significant performance benefit. I have also seen that the average DBA does
not generally understand the data or access patterns in the database. Given
that, they don't correctly setup table spaces in general, filesystem or raw.
Likewise, where it is possible to tie a tablespace to a memory buffer pool,
the average DBA does not setup it up to a performance advantage either.
However, are we talking about well tuned setups by someone who does
understand the data and the general access patterns? For a DBA like that,
they should be able to take advantage of these features and get significantly
better results. I would not say it requires considerable tuning, but an
understanding of data, storage and access patterns. Additionally, these
features did not cause our group considerable administrative overhead.

Jordan Henderson

On Thursday 30 October 2003 12:55, Sailesh Krishnamurthy wrote:
> DB2 supports cooked and raw file systems - SMS (System Manged Space)
> and DMS (Database Managed Space) tablespaces.
>
> The DB2 experience is that DMS tends to outperform SMS but requires
> considerable tuning and administrative overhead to see these wins.