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SQL Server Scalabilty - An Introduction Expand / Collapse
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Posted Wednesday, March 19, 2008 2:18 PM
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Once you move into the Windows Datacenter Edition world the hardware is highly available even with only one server.

http://www-03.ibm.com/systems/x/solutions/os/windows/datacenter.html

http://www.microsoft.com/windowsserver2003/datacenter/dcprogram.mspx

http://technet.microsoft.com/en-us/windowsserver/bb429508.aspx

and you have support levels from the vendors that are way beyond anything you get with a commodity server.


Joshua Perry
http://www.usesage.com
Post #471887
Posted Friday, March 21, 2008 7:28 AM
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I want such a server :D That'd be just awesome!!!

The article was correct but a tad short - it seems like the start of a series. I'd say that it's certainly easier from a developer's point of view to just throw more hardware at the problem for the database and have multiple identical web servers for the presentation layer.

Depending on your application you might be able to get away with some sort of merge replication or bidirectional transactional replication... Merge is probably safest but you'd want to have "sticky sessions" on your web servers so that a user who's working with database A will stick with database A for the duration of their session since their transactions may not have hit database B yet. For "admin" users who wish to see totals, etc they can either be aware of the latency of updates or use views to get bits of data from each database/server.



Post #472781
Posted Friday, May 30, 2008 4:34 PM
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@ Mr. Perry
32bit/x32 OS can not address more than 4GIG of RAM. Therefore, you can not assign 8gig of ram to a 32 bit guest VM. For additional detail re: how the USER MODE portion of the available RAM can be increased with caveats:
http://blogs.technet.com/askperf/archive/2007/03/23/memory-management-demystifying-3gb.aspx

I think the single node "massively VM" idea is a fun thought exercise, but that's all it is (with today's VM state of the art).

There is a third option I don't think was mentioned, forgive me if it was, and that would be using a distributed/n-Node read-only cache in front of the DB. A cache hit pulls the data/object from the distributed non-blocking cahce, a cache-miss is equivalent to a DB hit, of course all UPDATE/INSERT operatrions hit the DB. This is an accepted way to increasse read operations scalability in a linear fashion.

If you are interested in this concept, google/live search:
1. MEMCACHED
2. Oracle Coherence (Tangosol)
3. Scale Out Software

A fourth option is parallelization using multiple DB nodes fronted by a "parallel query and controller node" that sends the query to multiple back-end DB nodes (sort of like striping a drive, its like "striping a query" --> at a gross conceptual level).


Post #509409
Posted Saturday, May 31, 2008 8:37 AM
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adam cassel (5/30/2008)
@ Mr. Perry
32bit/x32 OS can not address more than 4GIG of RAM. Therefore, you can not assign 8gig of ram to a 32 bit guest VM. For additional detail re: how the USER MODE portion of the available RAM can be increased with caveats:
http://blogs.technet.com/askperf/archive/2007/03/23/memory-management-demystifying-3gb.aspx


I am aware of the /3GB and can't use it because that does not leave enough free PTEs for the backup software to run each night - my data volumes are all 300GB or more.

As for the statement about not being able to run 8GB in 32 bit, I have to disagree since I am currently doing that using AWE on all of my 32 bit SQL Servers. I have minmemory set to 2048 and maxmemory set to 6144 and my servers all take advantage of the 6GB available to them. As mentioned, this does require 32 bit enterprise edition of windows, which actually allows for 32GB of physical RAM.

http://technet.microsoft.com/en-us/library/ms179301.aspx
http://technet.microsoft.com/en-us/library/ms190731.aspx


Joshua Perry
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