Q: What kind of ratio should you expect to see between AWE Allocated and VM Committed/Reserved? We are running 8GB with a cap of 7GB in the max server memory and yet the VM Committed is around 100MB. I was first shocked to see that the sqlservice in task...

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...

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...

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...

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...

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...

Q. Under SQL Server 2000 Is the memtoleave concept still valid under 64-bit? A. Yes. If SQL Server’s component requests memory larger than 8 KB block, the block will be allocated outside of Buffer Pool. Remember, inside of SQL Server, Buffer Pool is...

The answer is No. The source of possible confusion came from one of my previous posts: http://blogs.msdn.com/slavao/archive/2005/11/15/493019.aspx . I apologize for the confusion. In order to make 64 bit version of SQL Server leverage locked pages all...

By now you have heard a lot about the fact that under WOW a 32 bit process can get 4GB of VAS. I agree this is great, but I would like you to be aware of something that might hit you really hard. As it turns out enabling 4GB VAS can be problematic due...

Q1 I read in your blog about the new algorithm with two clock hands to control memory consumption, but I really would like to understand exactly what the hands are doing and if they relate to the lazywriter. A1. In SQL Server 2005 we have separated...

Seems like today is a question day :-). I will attempt to answer several questions about VAS I got today: Q1. There is one aspect of Virtual Memory that is just not clear yet. I think I understand about VAS, but maybe not as much as I could, but I...

Today I received following question: Hello, We will be running Windows Server 2003 x64 with SQL Server 2005 x64. I would think AWE would not come into the picture in this scenario. I'm trying to find out more about SQL Server 2005 memory management...

As you would expect in the last several months SQL 2005 went through rigorous testing. During the period we have identified and put several improvements that you might be interested to hear about. Memory Broker Analyzing SQL Server's behavior...

Yesterday I gave a talk around SQL Server 2005's memory manager. The talk was rather chalk talk. It included memory manager changes in SQL 2005 as well as changes post CTP15. For the talk I prepared several slides - basically talking points that I thought...

Sometimes I am surprised how issues come up the moment you mention them J . Recently, I have discussed Soft NUMA configurations in the article http://blogs.msdn.com/slavao/articles/441058.aspx . This week one of our customers had an interesting problem...

SQL Server 2005 has been designed to take advantage of NUMA features exposed by both hardware and the Windows operating system. There are several caveats that you need to be aware when attempting to run SQL Server on NUMA platforms. In this post...

I just finished an article on how SQLOS helps SQL Server to leverage hardware capabilities http://blogs.msdn.com/slavao/articles/441058.aspx . It will be interesting to hear your comments, thoughts. Thanks a lot in advance

Q: I have teaching a class on Yukon for the Ascend program, and the class had a question I wanted to double check before answering. On an Itanium with 1 TB of RAM, the class’ curiosity asked, “If plan cache is very large “Then how does Plan Cache lookups...

We have already talked about Windows AWE mechanism on 32 bit and how SQL Server utilizes it. Today I would like to go over AWE & related mechanism on 64 bit platforms. To some people it comes as a surprise that AWE mechanism is still present...

Stack subject in Windows OS is fascinating. There are so many interesting technical problems surrounding it. The moment you think you fully understand everything about stack you suddenly discover yet another mystery. And so it goes. In the last couple...

Yukon caching vs SQL2000 What makes Yukon memory management different from SQL2000 is elaborative caching framework. In SQL2000 there are two major caches: data page cache, called Buffer Pool and procedure cache, cache of query plans. Buffer Pool and...

Resource Monitor and Memory Pressure When configuring SQL Server it is very important to understand how it reacts to memory pressure. I have already spent significant amount of time describing types of memory pressure. In this post you will understand...

You probably have used dbcc memory status command in SQL2000. In Yukon we have changed output of dbcc memorystatus to reflect new memory manager design, covered in my previous post. The first part of the output represents overall amount of memory consumed...

SQLOS's memory manager consists of several components such as memory nodes, memory clerks, memory caches, and memory objects. Fig 1. depicts memory manager components and their relationship: ---------------- | Memory Object | ---------------- | | V -...

With SQL Server 2005 Beta 1 and Beta 2 you might have noticed that there is no ums.dll in the bin directory. The reason is simple it is no longer exists. In SQL2000 ums.dll provided SQL Server with user mode non-preemptive scheduling. So what happened...