Re: Oracle block size - OS block size

From: Nuno Souto <nsouto_at_nsw.bigpond.net.au.nospam>
Date: Tue, 19 Jun 2001 09:34:15 GMT
Message-ID: <3b2f188b.1973054@news-server>

On 18 Jun 2001 12:41:43 -0700, bchorng_at_yahoo.com (Bass Chorng) wrote:

>
>I think most people choose 8K feeling it is safe. But this does not
>mean 2K is unrealistic.
>

Sure.

But given the vast majority of UNIX systems nowadays use a file system that has 4K or 8K blocks and most ORACLE databases now store their data in file systems, it's probably not too far off to suggest a baseline of 8K be used for UNIX. Special cases aside, of course.

Four years ago I was involved with a database that a bunch of drongos had set to 2K "because it was an OLTP system". Actually, it was a 3-tier client-server system, with a huge app server cache and heaps of very, very large overnight batch processing. All file systems had been set to 4K or 8K block size!

Once I finally cut through the "bureaucracy" of this bunch of idiots, the db_block_size was set to 4K as a first try. All batch runs immediately sliced the runtime into half with no visible or measurable impact on the on-line stuff. Makes me wonder where these "guidelines" came from...

Cheers
Nuno Souto
nsouto_at_bigpond.net.au.nospam
http://www.users.bigpond.net.au/the_Den/index.html Received on Tue Jun 19 2001 - 04:34:15 CDT