Re: Raw vs. Cooked

From: Austin Hackett <hacketta_57_at_yahoo.com>
Date: 17 Dec 2004 03:09:21 -0800
Message-ID: <1103281761.293955.128300@f14g2000cwb.googlegroups.com>

Hello All

I read the referenced article with interest as the database I am responsible for is hosted on an HP-UX 11i server and is raw-device based (the decision to use raw was before my time). However we are not using the async IO driver. This is where my question comes in. The paper concludes that:

"Where ease of management is not an issue and there is no application constraint, customers should always implement raw based database with async IO on HP-UX"

However, my reading of the evidence suggests to me that where ease of management is not an issue and there is no application constraint, customers should consider raw based database with async IO on HP-UX if the application is primarily write intensive. I notice that:

Filesystem with optimal mount options

DB_FILE_SEQUENTIAL_READ 14ms medium load and 19ms heavy load

Raw-device and no async IO driver

DB_FILE_SEQUENTIAL_READ 9ms medium load and 19ms heavy load

Raw-device and async IO driver

DB_FILE_SEQUENTIAL_READ 12ms medium load and 26ms heavy load

Read operations are the bottleneck in our database. I have never encountered a performance problem where write performance is the bottleneck. I have, on the other hand, encountered a number of performance problems where db_file_sequential_read was the primary response time component. This leads me to conclude that by not enabling the async IO driver I am on the write track. Am I missing something important here, or do others agree with my conclusions? Any advice appreciated

Thanks

Austin Received on Fri Dec 17 2004 - 05:09:21 CST