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From Oystein Grovlen - Sun Norway <Oystein.Grov...@Sun.COM>
Subject Re: [jira] Commented: (DERBY-801) Allow parallel access to data files.
Date Tue, 30 May 2006 07:28:23 GMT
Anders Morken (JIRA) wrote:
>     [ http://issues.apache.org/jira/browse/DERBY-801?page=comments#action_12413541 ]

> 
> Anders Morken commented on DERBY-801:
> -------------------------------------
> 
> I've found a benchmark to test this patch with, and quite frankly I'm not seeing any
difference in throughput between my patch and the original at all. 
> I've tested on a 4x400MHz Sun Enterprise 450 with a 10-disk ZFS raid0 of old disks for
data and logs and my own single-cpu 2,4GHz Athlon64 with a two disk raid0 for data and a single
disk for logs.

How large was your database?  Note that if the database is not 
substantially larger that the amount of physical memory, the file system 
may able to cache most of your data.  In that case, you will not gain 
much extra from concurrent I/O.

A metric I have found useful to is the average and maximum times for I/O 
requests.  That can give some indications on the queuing effects of I/O. 
  I have just measured the time by calls to System.currentTimeMillis() 
in readPage/writePage.

-- 
Øystein

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