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From Oystein Grovlen - Sun Norway <Oystein.Grov...@Sun.COM>
Subject Re: Derby I/O issues during checkpointing
Date Tue, 28 Mar 2006 12:12:48 GMT
Raymond Raymond wrote:

>> I ran a variant of the TPC-B benchmark with a large database (20 GB) 
>> and  a large page cache (1 GB).  I do not think you need TPC-B 
>> transactions to see this, but I think you need update-intensive 
>> transactions that frequently needs to load pages from disk.  For 
>> example, single record updates where an index is used to locate the 
>> record.  You will also need several connections in parallel (e.g., 20).
>> -- 
>> Øystein
> Thanks for your answer. Did you use some tools to know something like
> "single write operations that took almost 12 seconds" and "read requests
> that took more than 20 seconds". I downloaded TPC-B benchmark program,
> it didn't give me those kind of information. I want to know how did you
> know the time for reads and writes.^_^.

No special tools.  Our TPCB-client writes the number of committed 
transaction for each 10 second interval.  That way, I observed regular 
drops in throughput.  I/O response times was measured by instrumenting 
RAFContainer to measure the time it takes to do seek and read/write. 
This was written to derby.log and inspected manually.  (See attached 
diff from RAFContainer.readPage for an example)

Øystein Grøvlen, Senior Staff Engineer
Sun Microsystems, Database Technology Group
Trondheim, Norway

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