Re: performace effects of large vs small number of datafiles

From: Ken Nichols <knichols_at_mcsilo.ilo.dec.com>
Date: 1997/09/23
Message-ID: <34277DCA.5B3C@mcsilo.ilo.dec.com>#1/1

Mike

As I recall, one problem with many small datafiles is that an extent can't span more than one datafile. So if you had a lot of 2GB datafiles, your largest possible extent would be 2GB. This may not be a problem if you have many small tables, but a large table (e.g., data warehouse) would have to be spread across many extents, thus incurring extra extent-management overhead.

On the other hand, many small disks give you more spindles working for you, so there's more I/O parallelism.

Ken

Mike Phillips wrote:
>
> Given that one has a reasonably large database, say 100GB, is it better to
> have 50 2GB raw devices, 2 50GB devices or something in between? This is
> on a 10CPU Sun E6000 w/ 600GB DASD managed by veritas and 6GB RAM. Pros?
> Cons?
Received on Tue Sep 23 1997 - 00:00:00 CDT