I try to understand what the Very Large Dimension Manager is and how it
works.

Should handle VLD in an separate external Windows Process (msmdvldm.exe) ?
How to activate (Should handle dimensions where the dimtree file size is
bigger then the Regkey "VLDMThreshold" ) ?
How to validate a proper work and whats the difference to normal dimensions?

It seems this feature doesn´t work on my machines because I have set the
regkey to 45 instead of the default value of 64 MB - and I have several
dimensions with an bigger dimtree file - but there is no change in the AS2K
startup (no second process, ...)

Is my understanding not correct ?

Hannes

Analysis Services will spawn a separate process for each dimension that
exceeds the threshold value. Even though the file size might be bigger than
your threshold value, it doesn't necessarily mean that that is how much
memory Analysis Services will need to store that dimension in memory. It's
a fairly good approximation though.

We generally recommend that you only use the VLDM if there is a need. If
you have enough memory on the server to not use the VLDM process, you'll
probably get better performance without using it since it requires out of
process communication with the server.

Sean


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Sean

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Sean Boon
SQL Server BI Product Unit

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"Hannes Mayer" <hmayer (AT) mis (DOT) at> wrote

I have tried the VLDM again with an very low value in the threshold (12
MB) - with this value AS2K uses the msmdvldm.exe to load my 9 customer
dimensions in separate memory space.
Is there a way to calculate the value exactly?
Is this value dependend of the physical available memeory because me
testserver has only 1.5GB and the operativ one has 3.5GB?

My Problem are the 9 Customer Hierarchies (Dimensions) each with at least
200 000 base Elements where all the files for for one of this hierarchies
have (ca. 100 - 120 MB) - after the Server start and the incremental process
of the dimensions I cannot process a partition of one cube because I get an
Server Memory error - and the prcess has the High Limit of 2GB - the limit
of the Operation System of this machine (W2K Server). I want to try an
workarond with the VLDM - or can you recomand othere ways with no changes on
the dimensions ?

Is the performance impact with the vldm noticeable in userqueries compared
without the vldm? Is it possible to say response time will increase by an
specific factor or ?

Thanks for any information
Hannes

Sean Boon [MS] wrote:

This is one of those scenarios where it really "just depends". 9 Customer
hierarchies does sound like a lot, so my first recommendation would be to
examine if you really need that many.

Another option that you have is that you can enable Analysis Services to use
3 GB of virtual memory by modifying the boot.ini file. There is a KB
article posted on it, I just don't have the link handy at the moment, but
you should be able to search for it on msdn.com or
www.microsoft.com/support.

As far as the expected increase in user query response time, that is really
difficult to tell. It's out of process communication so it will more than
likely be slower, but I couldn't even venture to guess on the specific
amount. It would more than likely be entirely dependent on the specifics of
your implementation.

Another option to consider would be to use 64-bit Analysis Services. The
64-bit version of Analysis Services is not limited in it's memory usage
since processes are not limited to using 2 GB of virtual memory.

Sean
--
Sean

--
Sean Boon
SQL Server BI Product Unit

--
This posting is provided "AS IS" with no warranties, and confers no rights.
Use of included script samples are subject to the terms specified at
http://www.microsoft.com/info/cpyright.htm.










"Hannes Mayer" <hmayer (AT) mis (DOT) at> wrote