Re: 32bit vs 64bit ?

Paolo Bertiglia (pbertigl_at_io.com) wrote:
: Digital's brochure about their XAP servers and the 64 bit OpenVMS claim an
: houndredfold advantage for a database (Rdb & Oracle) that use a 64 bit Very
: Large Memory model over the same but only 32 bit software.
 

: I understand that you have a much larger address space in 64 bit but how this
: can be translated in a so big performance advantage?

The answer is simple:

As you mention 64 bit allows for a much larger address space.

As I understand the only difference between a traditional Oracle Server and Oracle Server VLM is the size of the SGA which can be very very large in the VLM version.

So: The performance advantage is primarely due to the fact that a big chunk of your data resides in physical memory and therefore access is fast. The machines that DEC uses for these databases are typically configured with 6-14 Gb of memory.

This performance advantage is for real but it would be interesting to see a comparison between two similar DEC machines, one running in 32 bit and the other in 64 bit, but both with the same size SGA.

Lars Bruun Hansen

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