Re: 2 GB myth

"Howard J. Rogers" <hjr_at_dizwell.com> wrote in message news:<41a2a9e6$0$20863$afc38c87_at_news.optusnet.com.au>...
> Igor Laletin wrote:
>
> > Not really. A number of datafiles doesn't have much impact on your
> > workload. Also smaller datafiles usually don't mean much faster
> > datafile recovery. True, you may get it restored on a disk a bit
> > faster. The difference would be small though - current tape drives
> > restore at 1G+/min. After that you still need to go through all redo
> > logs and it's the same for any datafile size.
>
> Have you used RMAN to backup a database. The number of data files is a
> heavy determinant of how well it can parallelise the operation. It can
> make a big difference.

Well I was talking about recovery, not backup. Anyway, even with backups, most sites do them to the tapes. The tape drives are usually a bottleneck, not small number of datafiles. Say, you have four drives multiplexed by four (four processes feed data to one drive to keep it busy). You only need 16 datafiles to fully utilise tapes. Having 1K 2G datafiles instead of 100x20G won't make your backups faster.

> HJR
Igor Received on Tue Nov 23 2004 - 19:24:19 CST