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From Alex Karasulu <aok...@bellsouth.net>
Subject [ApacheDS] Speeding up writes (synchOnWrite)
Date Tue, 29 Aug 2006 04:44:42 GMT
Hi all,

I was playing around with write performance with and without the 
synchOnWrite feature enabled. As you know this feature is enabled out of 
the box.  It syncs caches to disk everytime there is a write based 
operation such as add, delete, modify, and modifyDN.

To turn it off just set it to false for each partition in your 
server.xml file.  It can be configured differently for each partition. 
Hence it's really a partition configuration property.

I'm using my lousy old dual Athlon MP server to demonstrate the big 
difference this parameter makes.

Setup
-----
Dual Athlon MP 1900
2 GB of Memory
OS Ubuntu 6.06 kernel 2.6.15
SUN JVM 1.5.0_08

Here's some results on the big difference this flag makes on bulk loads.

Results
-------
10k entries added *without* synchOnWrite [59.009 seconds]
10k entries added with synchOnWrite [46m27.340s]

(Just for the heck of it)
10k entries returned via search [11.361 seconds]


Yes that's correct 59 seconds verses 2787 seconds or 46m27.340s.  Yeah 
you can say wow now.  The difference is amazing at 47X faster adds.


Conclusion
----------

For bulk loads you really want to turn off synchOnWrite.  After the load 
is complete you can turn synchOnWrites on for data integrity.

It would be nice to be able to turn this flag on and off live without a 
server restart wouldn't it?

Alex

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