Q & A: I am running on 64 bit and all of my tasks are waiting on SOS_RESERVEDMEMBLOCKLIST, What is going on?

This wait type represents waiting on multi page allocations inside of SQLOS’s memory manager. As you remember from my description of memory manager’s working internals, it has two major allocators single page allocator, SPA and multi page allocator, MPA. Majority of the time SQL Server internal code uses SPA, however in some cases it will…

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SQLOSDMV’s Continue

sys.dm_os_waiting_tasks One can run lots of interesting queries using this view.  You can even use this view to perform deadlock detection that is not resolvable by deadlock monitor, DM. For example if you have tasks waiting on external resources such as extended stored procedures and blocking others from running. This type of deadlock DM can’t…

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Q & A: Does SQL Server always respond to memory pressure?

Q: I thought I’ve seen reference recently to problems with SQL2005 not releasing memory when under pressure, and this was possibly due to the Lock Pages In Memory option. We have a server where this seems to be happening, i.e. SQL2005 uses all available memory and the server basically dies because there’s no memory left…

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SQLOS’s DMVs Continue

sys.dm_os_schedulers Q. Do I need to by more CPUs? In order to answer this question you have to find out if your load is really CPU bounded.  Your load is really CPU bounded if a number of runnable tasks per each scheduler always greater than 1 and all of your queries have correct plan.  The…

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SQLOS’s DMVs

SQL Server 2005 has a large number of DMVs that you can take advantage of especially when you try to understand behavioral characteristics of your SQL Server 2005 installation. DMVs expose enormous amount of information but how can you make use of it? What questions you can answer using DMVs?    So in order to…

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Talking points around SQL Server 2005 scalability

Couple of weeks ago I did a talk on SQL Server 2005 scalability. The actual talk was not about the enormous amount of features that you can leverage in SQL Serve 2005 to make your application scale but rather how SQL 2005 achieves its scalability. In this post I present a set of talking points…

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Q & A: I can’t make SQL Server 2005 32 bit version to use all memory on the machine

I’m currently using the RTM+SP1 x86-SQL2005 build on a server which has 32GB of physical memory.  I notice that during ramp-up the memory usage (as seen under task manager) increases to about 28GB (i.e. “Available memory” reduces to 4GB) and stays there.      Is there a way to get around this and make SQL…

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Set of new features in SQL Server 2005 enabled by SQLOS

Couple of weeks ago I had a chance to visit set of our customers and talk to them directly. It was an unforgettable experience. As a part of the visit I made set of presentations related to SQLOS and new features it enables in SQL Server 2005. I thought that some of you might be…

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Q and A: Enabling AWE settings for SQL Server 32 bit edition in WOW

Q.  A customer wants to run SQL 2000 SP4 in a Windows Server 2003 SP1 x64 edition. They did the installation without problems but SQL Server is not using more than 4GB of memory.  Is it possible to enable AWE in this configuration? A.  The answer is yes, you should follow exactly the same procedure…

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Q and A: Some questions about output from dbcc memorystatus

Recently I have recieved following question:  A customer of mine is getting this output on an Itanium with 16GB of memory: Memory Manager                      KB —————————— ——————– VM Reserved                           16979888 VM Committed                         217928 AWE Allocated                         14116272 Reserved Memory                     1024 Reserved Memory In Use            0   Q. How can VM Committed be so much less than AWE Allocated, or is this counter…

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