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Can you please tell whether there are advantages in the transition from 32-bit to 64-bit architecture for the SQL Anywhere 12 server on a 64-bit Windows operating system? |
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From the comments on: http://iablog.sybase.com/paulley/2008/04/dynamic-memory-management/
The above description was assuming a 32-bit OS. The only changes from a move to a 64-bit OS and a 32-bit process vs a 64-bit process is that the base amount of memory increases to about ~3.6GB in a 32-bit process, then AWE is used. The same limitations about AWE still apply. In short, always use the 64-bit database server on a 64-bit operating system where possible if you wish for the database server to directly use all of the memory (rather than have the expense of memory swapping to simulate this with a 32-bit AWE). Also notably, AWE extensions (dbsrv12 -cw) are deprecated. Thank you very much for Your answer. However, I would like to clarify some details. So, Glenn Paulley wrote that: "There is little difference in the operation of the cache manager between 64- and 32-bit architectures with (or without) AWE. In all cases the cache manager must keep track of all pages in the buffer pool; the difference is that with AWE a page may not have a page frame in addressable memory. If a page is required by a thread and is not in addressable memory, the cache manager determines a victim and makes the AWE call to swap the victim page to extended storage; and then makes a second call to make the required page addressable. This is done through page table manipulations rather than memcpy, so it’s not that expensive (though nothing is free)." Does it follow that the cost usage of AWE-memory for 32-bit SQL Anywhere is only the support "page table manipulations"-mechanism? In my opinion, this board is still very small. Or the use of AWE-memory requires additional exchange (which is absent for 64-bit SQL Anywhere), for example, between RAM and disk?
(07 Feb '13, 01:39)
Ilia63
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I'll let Glenn answer this question again:
Again, we highly emphasize to always use the 64-bit database server, wherever possible. The technical details behind this rationale agree with this recommendation.
(07 Feb '13, 12:24)
Jeff Albion
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If you are using AWE currently, you may consider John's answer in this FAQ.
The case of the small amount of RAM can not be considered. Assume we have an lot of RAM (but, <= 64 GB for Windows Server 2008 Enterprise).
My hint was not focussed on that particular user's problem but on the general explanation John has given to the limitations of AWE (e.g. no dynamic cache sizing, not swappable, particular (and more expensive) addressing mode and the like).
As I understand his profound answer, he makes a general recommendation for "bigger" databases on 64-bit Windows to use a 64-bit database engine instead of a 32-bit engine with AWE.