Hi all!
After doing some extensive testing with a directory container storagepool I 
noticed a significant change compared to the old traditional storage pools.
In a traditional storage pool TSM stores a file like an object. In most cases 
one file is one object as far as I could see. Deleting this data is very fast: 
a delete filespace runs rather fast because TSM only has to delete the objects. 
So deleting a large database client with multiple TBs takes a few seconds or 
maybe a few minutes.
When you are using a container storage pool everything changes. Files are still 
stored as objects, but objects are split into chunks. The average size of a 
chuck is approx. 100 KB and TSM performs dedup on this chuck level. So if you 
now delete a large file, TSM has to inspect every chunk to see if it is unique 
or not. When it is unique it will be deleted, otherwise not. If you delete a 
file which is for instance 40 GB in size, TSM has to inspect around 420,000 
chucks before the object can be deleted. I noticed that this takes several 
seconds to complete, so one has to take into consideration that the deletion of 
large clients requires significant more time to complete than one is used to.
Deleing a client with little more than 1 TB of Oracle data was running for more 
than 20 minutes. So a delete filespace for really large database clients can 
run for hours! Has anyone else noticed this behavior too?
Kind regards,
Eric van Loon
Air France/KLM Storage Engineering
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