Jeffrey,

On 1/31/06 8:09 PM, "Jeffrey W. Baker" <[EMAIL PROTECTED]> wrote:
>> ... Prove it.
> I think I've proved my point.  Software RAID1 read balancing provides
> 0%, 300%, 100%, and 100% speedup on 1, 2, 4, and 8 threads,
> respectively.  In the presence of random I/O, the results are even
> better.
> Anyone who thinks they have a single-threaded workload has not yet
> encountered the autovacuum daemon.

Good data - interesting case.  I presume from your results that you had to
make the I/Os non-overlapping (the "skip" option to dd) in order to get the
concurrent access to work.  Why the particular choice of offset - 3.2GB in
this case?

So - the bandwidth doubles in specific circumstances under concurrent
workloads - not relevant to "Huge Data sets, simple queries", but possibly
helpful for certain kinds of OLTP applications.

- Luke 



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