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Re: (ITS#3851) Berkeley DB Scalability Patch

--On Thursday, July 28, 2005 2:56 PM -0400 Jong-Hyuk 
<jongchoi@watson.ibm.com> wrote:

>> Hi Jong,
>> I don't think you read my email very closely.
>> 1) I noted I don't have systems with large amounts of RAM to test
>> large databases on.
> Although I'm testing the BDB scalability patch on a machine having 12GB
> RAM, the BDB cache size is set to only 1.6GB. It's a 32-bit platform.
> What is  obvious between the lines of the performance results of the BDB
> scalability patch is that the patch makes it possible to add large
> databases in memory constrained systems which is typical in small to
> medium scale servers such as IBM BladeCenter and OpenPower. Hence, you
> should not consider not having a large amount of RAM as an inhibitor to
> large database experiments.

I have to say that you are very wrong here.  You must consider not having a 
sufficient amount of overhead RAM as an inhibitor to large database 
environments.  I've moved from doing my testing of the 2 million DB 
database with a 1.6GB DB Cache from a system with 2GB of memory to a system 
with 3GB of memory.  There is an extreme difference in performance.  So 
while your patch might make things work better in a limited memory 
environment (I still have yet to see any evidence of this, but I continue 
to experiment), there are still requirements for some amount of overhead 
memory availability that must be met.


Quanah Gibson-Mount
Product Engineer
Symas Corporation
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