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  • SQLOS and Cloud Infrastructure sessions at PASS Summit 2012

    - by SQLOS Team
    The SQL Pass Summit 2012, the largest yet, is in full swing. Here's a summary of the sessions this week on cloud infrastructure and SQLOS topics. Some of these were today, and you can catch the recordings. One more session takes place on Friday covering SQL Server solution patterns in Windows Azure VMs... Also, catch Thursday's keynote with Quentin Clark which will feature a cool IaaS demo!   SQL Server in Windows Azure VM Sessions CLD-309-A SQLCAT: Best Practices and Lessons Learned on SQL Server in an Azure VM Steve Howard, Arvind Ranasaria - Wednesday 11/6 10:15 This session looked at some best practices to optimize Networking, Memory, Disk IO and high availability based on lessons learned during SQLCat work with customer deployments. Well worth catching the recording.   SQL Server in Azure VM patterns: Hybrid Disaster Recovery, data movement and BI Guy Bowerman, Peter Saddow, Michael Washam, Ross LoForte - Friday 11/9 9:45 Rm 613 [Note: In the guides this has an outdated title.] This session has a focus on SQL Server Azure VM solutions. Starting with the basics and then going deeper into: - New features in the Microsoft Assessment and Planning Toolkit 8.0 to help plan and size SQL VM migrations.- A Look at a Windows Azure VM SQL Server app making use of load balancing and SQL Server high availability features.- A BI case study running SQL BI components in Azure VMs and making use of Windows 8 tiles.- A training class in a VM case study.   SQLOS Sessions DBA-500-HD Inside SQLOS 2012 (half-day session) Bob Ward - Wednesday 11/6 1:30pm Bob Ward from CSS applies his wealth of experience to look at the internals of SQLOS and what's changed in the various SQL 2012 components, including memory, resource governor, scheduler.   DBA-403-M: SQLCAT: Memory Manager Changes in SQL Server 2012 Gus Apostol, Jerome Halmans - 1:30pm Covers the redesigned SQLOS memory manager in SQL Server 2012 including the new page allocator for any size pages (and all that implies), DMVs, demo's. Not sure why this was placed at the same time as the SQLOS half-day session, but since it's recorded it's available for catch-up.   - Guy   Originally posted at http://blogs.msdn.com/b/sqlosteam/

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  • New SQLOS features in SQL Server 2012

    - by SQLOS Team
    Here's a quick summary of SQLOS feature enhancements going into SQL Server 2012. Most of these are already in the CTP3 pre-release, except for the Resource Governor enhancements which will be in the release candidate. We've blogged about a couple of these items before. I plan to add detail. Let me know which ones you'd like to see more on: - Memory Manager Redesign: Predictable sizing and governing SQL memory consumption: sp_configure ‘max server memory’ now limits all memory committed by SQL ServerResource Governor governs all SQL memory consumption (other than special cases like buffer pool) Improved scalability of complex queries and operations that make >8K allocations Improved CPU and NUMA locality for memory accesses Single memory manager that handles page allocations of all sizes Consistent Out-of-memory handling & management across different internal components - Optimized Memory Broker for Column Store indexes (Project Apollo) - Resource Governor Support larger scale multi-tenancy by increasing Max. number of resource pools20 -> 64 [for 64-bit] Enable predictable chargeback and isolation by adding a hard cap on CPU usage Enable vertical isolation of machine resources Resource pools can be affinitized to individual or groups of schedulers or to NUMA nodes New DMV for resource pool affinity  - CLR 4 support, adds .NET Framework 4 advantages - sp_server_dianostics Captures diagnostic data and health information about SQL Server to detect potential failures Analyze internal system state Reliable when nothing else is working   - New SQLOS DMVs (in 2008 R2SP1) SQL Server related configuration - New DMVsys.dm_server_services OS related resource configurationNew DMVssys.dm_os_volume_statssys.dm_os_windows_infosys.dm_server_registry XEvents for SQL and OS related Perfmon counters Extend sys.dm_os_sys_info See previous blog posts here and here. - Scale / Mission critical Increased scalability: Support Windows 8 max memory and logical processorsDynamic Memory support in Standard Edition - Hot-Add Memory enabled when virtualized - Various Tier1 Performance Improvements, including reduced instructions for superlatches. Originally posted at http://blogs.msdn.com/b/sqlosteam/

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  • SQL University: Parallelism Week - Introduction

    - by Adam Machanic
    Welcome to Parallelism Week at SQL University . My name is Adam Machanic, and I'm your professor. Imagine having 8 brains, or 16, or 32. Imagine being able to break up complex thoughts and distribute them across your many brains, so that you could solve problems faster. Now quit imagining that, because you're human and you're stuck with only one brain, and you only get access to the entire thing if you're lucky enough to have avoided abusing too many recreational drugs. For your database server,...(read more)

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  • SQL University: Parallelism Week - Introduction

    - by Adam Machanic
    Welcome to Parallelism Week at SQL University . My name is Adam Machanic, and I'm your professor. Imagine having 8 brains, or 16, or 32. Imagine being able to break up complex thoughts and distribute them across your many brains, so that you could solve problems faster. Now quit imagining that, because you're human and you're stuck with only one brain, and you only get access to the entire thing if you're lucky enough to have avoided abusing too many recreational drugs. For your database server,...(read more)

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  • When was sys.dm_os_wait_stats last cleared?

    - by SQLOS Team
    The sys.dm_os_wait_stats DMV provides essential metrics for diagnosing SQL Server performance problems. Returning incrementally accumulating information about all the completed waits encountered by executing threads it is a useful way to identify bottlenecks such as IO latency issues or waits on locks. The counters are reset each time SQL server is restarted, or when the following command is run: DBCC SQLPERF ('sys.dm_os_wait_stats', CLEAR); To make sense out of these wait values you need to know how they change over time. Suppose you are asked to troubleshoot a system and you don't know when the wait stats were last zeroed. Is there any way to find the elapsed time since this happened? If the wait stats were not cleared using the DBCC SQLPERF command then you can simply correlate the stats with the time SQL Server was started using the sqlserver_start_time column introduced in SQL Server 2008 R2: SELECT sqlserver_start_time from sys.dm_os_sys_info However how do you tell if someone has run DBCC SQLPERF ('sys.dm_os_wait_stats', CLEAR) since the server was started, and if they did, when? Without this information the initial, or historical, wait_stats have less value until you can measure deltas over time. There is a way to at least estimate when the stats were last cleared, by using the wait stats themselves and choosing a thread that spends most of its time sleeping. A good candidate is the SQL Trace incremental flush task, which mostly sleeps (in 4 second intervals) and in between it attempts to flush (if there are new events – which is rare when only default trace is running) – so it pretty much sleeps all the time. Hence the time it has spent waiting is very close to the elapsed time since the counter was reset. Credit goes to Ivan Penkov in the SQLOS dev team for suggesting this. Here's an example (excuse formatting): 144 seconds after the server was started: select top 10 wait_type, wait_time_ms from sys.dm_os_wait_stats order by wait_time_ms desc wait_type                                                               wait_time_ms--------------------------------------------------------------------------------------------------------------- XE_DISPATCHER_WAIT                                      242273LAZYWRITER_SLEEP                                          146010LOGMGR_QUEUE                                                145412DIRTY_PAGE_POLL                                             145411XE_TIMER_EVENT                                               145216REQUEST_FOR_DEADLOCK_SEARCH             145194SQLTRACE_INCREMENTAL_FLUSH_SLEEP    144325SLEEP_TASK                                                        73359BROKER_TO_FLUSH                                           73113PREEMPTIVE_OS_AUTHENTICATIONOPS       143 (10 rows affected) Reset: DBCC SQLPERF('sys.dm_os_wait_stats', CLEAR)" DBCC execution completed. If DBCC printed error messages, contact your system administrator. After 8 seconds: select top 10 wait_type, wait_time_ms from sys.dm_os_wait_stats order by wait_time_ms desc wait_type                                                                 wait_time_ms--------------------------------------------------------------------------------------------------------------------- REQUEST_FOR_DEADLOCK_SEARCH              10013LAZYWRITER_SLEEP                                           8124SQLTRACE_INCREMENTAL_FLUSH_SLEEP     8017LOGMGR_QUEUE                                                 7579DIRTY_PAGE_POLL                                              7532XE_TIMER_EVENT                                                5007BROKER_TO_FLUSH                                            4118SLEEP_TASK                                                         3089PREEMPTIVE_OS_AUTHENTICATIONOPS        28SOS_SCHEDULER_YIELD                                   27 (10 rows affected)   After 12 seconds: select top 10 wait_type, wait_time_ms from sys.dm_os_wait_stats order by wait_time_ms desc wait_type                                                                  wait_time_ms------------------------------------------------------------------------------------------------------ REQUEST_FOR_DEADLOCK_SEARCH               15020LAZYWRITER_SLEEP                                            14206LOGMGR_QUEUE                                                  14036DIRTY_PAGE_POLL                                               13973SQLTRACE_INCREMENTAL_FLUSH_SLEEP      12026XE_TIMER_EVENT                                                 10014SLEEP_TASK                                                          7207BROKER_TO_FLUSH                                             7207PREEMPTIVE_OS_AUTHENTICATIONOPS         57SOS_SCHEDULER_YIELD                                     28 (10 rows affected) It may not be accurate to the millisecond, but it can provide a useful data point, and give an indication whether the wait stats were manually cleared after startup, and if so approximately when. - Guy     Originally posted at http://blogs.msdn.com/b/sqlosteam/

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  • SQL Server and Hyper-V Dynamic Memory Part 2

    - by SQLOS Team
    Part 1 of this series was an introduction and overview of Hyper-V Dynamic Memory. This part looks at SQL Server memory management and how the SQL engine responds to changing OS memory conditions.   Part 2: SQL Server Memory Management As with any Windows process, sqlserver.exe has a virtual address space (VAS) of 4GB on 32-bit and 8TB in 64-bit editions. Pages in its VAS are mapped to pages in physical memory when the memory is committed and referenced for the first time. The collection of VAS pages that have been recently referenced is known as the Working Set. How and when SQL Server allocates virtual memory and grows its working set depends on the memory model it uses. SQL Server supports three basic memory models:   1. Conventional Memory Model   The Conventional model is the default SQL Server memory model and has the following properties: - Dynamic - can grow or shrink its working set in response to load and external (operating system) memory conditions. - OS uses 4K pages – (not to be confused with SQL Server “pages” which are 8K regions of committed memory).- Pageable - Can be paged out to disk by the operating system.   2. Locked Page Model The locked page memory model is set when SQL Server is started with "Lock Pages in Memory" privilege*. It has the following characteristics: - Dynamic - can grow or shrink its working set in the same way as the Conventional model.- OS uses 4K pages - Non-Pageable – When memory is committed it is locked in memory, meaning that it will remain backed by physical memory and will not be paged out by the operating system. A common misconception is to interpret "locked" as non-dynamic. A SQL Server instance using the locked page memory model will grow and shrink (allocate memory and release memory) in response to changing workload and OS memory conditions in the same way as it does with the conventional model.   This is an important consideration when we look at Hyper-V Dynamic Memory – “locked” memory works perfectly well with “dynamic” memory.   * Note in “Denali” (Standard Edition and above), and in SQL 2008 R2 64-bit (Enterprise and above editions) the Lock Pages in Memory privilege is all that is required to set this model. In 2008 R2 64-Bit standard edition it also requires trace flag 845 to be set, in 2008 R2 32-bit editions it requires sp_configure 'awe enabled' 1.   3. Large Page Model The Large page model is set using trace flag 834 and potentially offers a small performance boost for systems that are configured with large pages. It is characterized by: - Static - memory is allocated at startup and does not change. - OS uses large (>2MB) pages - Non-Pageable The large page model is supported with Hyper-V Dynamic Memory (and Hyper-V also supports large pages), but you get no benefit from using Dynamic Memory with this model since SQL Server memory does not grow or shrink. The rest of this article will focus on the locked and conventional SQL Server memory models.   When does SQL Server grow? For “dynamic” configurations (Conventional and Locked memory models), the sqlservr.exe process grows – allocates and commits memory from the OS – in response to a workload. As much memory is allocated as is required to optimally run the query and buffer data for future queries, subject to limitations imposed by:   - SQL Server max server memory setting. If this configuration option is set, the buffer pool is not allowed to grow to more than this value. In SQL Server 2008 this value represents single page allocations, and in “Denali” it represents any size page allocations and also managed CLR procedure allocations.   - Memory signals from OS. The operating system sets a signal on memory resource notification objects to indicate whether it has memory available or whether it is low on available memory. If there is only 32MB free for every 4GB of memory a low memory signal is set, which continues until 64MB/4GB is free. If there is 96MB/4GB free the operating system sets a high memory signal. SQL Server only allocates memory when the high memory signal is set.   To summarize, for SQL Server to grow you need three conditions: a workload, max server memory setting higher than the current allocation, high memory signals from the OS.    When does SQL Server shrink caches? SQL Server as a rule does not like to return memory to the OS, but it will shrink its caches in response to memory pressure. Memory pressure can be divided into “internal” and “external”.   - External memory pressure occurs when the operating system is running low on memory and low memory signals are set. The SQL Server Resource Monitor checks for low memory signals approximately every 5 seconds and it will attempt to free memory until the signals stop.   To free memory SQL Server does the following: ·         Frees unused memory. ·         Notifies Memory Manager Clients to release memory o   Caches – Free unreferenced cache objects. o   Buffer pool - Based on oldest access times.   The freed memory is released back to the operating system. This process continues until the low memory resource notifications stop.    - Internal memory pressure occurs when the size of different caches and allocations increase but the SQL Server process needs to keep its total memory within a target value. For example if max server memory is set and certain caches are growing large, it will cause SQL to free memory for re-use internally, but not to release memory back to the OS. If you lower the value of max server memory you will generate internal memory pressure that will cause SQL to release memory back to the OS.    Memory pressure handling has not changed much since SQL 2005 and it was described in detail in a blog post by Slava Oks.   Note that SQL Server Express is an exception to the above behavior. Unlike other editions it does not assume it is the most important process running on the system but tries to be more “desktop” friendly. It will empty its working set after a period of inactivity.   How does SQL Server respond to changing OS memory?    In SQL Server 2005 support for Hot-Add memory was introduced. This feature, available in Enterprise and above editions, allows the server to make use of any extra physical memory that was added after SQL Server started. Being able to add physical memory when the system is running is limited to specialized hardware, but with the Hyper-V Dynamic Memory feature, when new memory is allocated to a guest virtual machine, it looks like hot-add physical memory to the guest. What this means is that thanks to the hot-add memory feature, SQL Server 2005 and higher can dynamically grow if more “physical” memory is granted to a guest VM by Hyper-V dynamic memory.   SQL Server checks OS memory every second and dynamically adjusts its “target” (based on available OS memory and max server memory) accordingly.   In “Denali” Standard Edition will also have sqlserver.exe support for hot-add memory when running virtualized (i.e. detecting and acting on Hyper-V Dynamic Memory allocations).   How does a SQL Server workload in a guest VM impact Hyper-V dynamic memory scheduling?   When a SQL workload causes the sqlserver.exe process to grow its working set, the Hyper-V memory scheduler will detect memory pressure in the guest VM and add memory to it. SQL Server will then detect the extra memory and grow according to workload demand. In our tests we have seen this feedback process cause a guest VM to grow quickly in response to SQL workload - we are still working on characterizing this ramp-up.    How does SQL Server respond when Hyper-V removes memory from a guest VM through ballooning?   If pressure from other VM's cause Hyper-V Dynamic Memory to take memory away from a VM through ballooning (allocating memory with a virtual device driver and returning it to the host OS), Windows Memory Manager will page out unlocked portions of memory and signal low resource notification events. When SQL Server detects these events it will shrink memory until the low memory notifications stop (see cache shrinking description above).    This raises another question. Can we make SQL Server release memory more readily and hence behave more "dynamically" without compromising performance? In certain circumstances where the application workload is predictable it may be possible to have a job which varies "max server memory" according to need, lowering it when the engine is inactive and raising it before a period of activity. This would have limited applicaability but it is something we're looking into.   What Memory Management changes are there in SQL Server “Denali”?   In SQL Server “Denali” (aka SQL11) the Memory Manager has been re-written to be more efficient. The main changes are summarized in this post. An important change with respect to Hyper-V Dynamic Memory support is that now the max server memory setting includes any size page allocations and managed CLR procedure allocations it now represents a closer approximation to total sqlserver.exe memory usage. This makes it easier to calculate a value for max server memory, which becomes important when configuring virtual machines to work well with Hyper-V Dynamic Memory Startup and Maximum RAM settings.   Another important change is no more AWE or hot-add support for 32-bit edition. This means if you're running a 32-bit edition of Denali you're limited to a 4GB address space and will not be able to take advantage of dynamically added OS memory that wasn't present when SQL Server started (though Hyper-V Dynamic Memory is still a supported configuration).   In part 3 we’ll develop some best practices for configuring and using SQL Server with Dynamic Memory. Originally posted at http://blogs.msdn.com/b/sqlosteam/

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  • SQL Server and Hyper-V Dynamic Memory - Part 1

    - by SQLOS Team
    SQL and Dynamic Memory Blog Post Series   Hyper-V Dynamic Memory is a new feature in Windows Server 2008 R2 SP1 that allows the memory assigned to guest virtual machines to vary according to demand. Using this feature with SQL Server is supported, but how well does it work in an environment where available memory can vary dynamically, especially since SQL Server likes memory, and is not very eager to let go of it? The next three posts will look at this question in detail. In Part 1 Serdar Sutay, a program manager in the Windows Hyper-V team, introduces Dynamic Memory with an overview of the basic architecture, configuration and monitoring concepts. In subsequent parts we will look at SQL Server memory handling, and develop some guidelines on using SQL Server with Dynamic Memory.   Part 1: Dynamic Memory Introduction   In virtualized environments memory is often the bottleneck for reaching higher VM densities. In Windows Server 2008 R2 SP1 Hyper-V introduced a new feature “Dynamic Memory” to improve VM densities on Hyper-V hosts. Dynamic Memory increases the memory utilization in virtualized environments by enabling VM memory to be changed dynamically when the VM is running.   This brings up the question of how to utilize this feature with SQL Server VMs as SQL Server performance is very sensitive to the memory being used. In the next three posts we’ll discuss the internals of Dynamic Memory, SQL Server Memory Management and how to use Dynamic Memory with SQL Server VMs.   Memory Utilization Efficiency in Virtualized Environments   The primary reason memory is usually the bottleneck for higher VM densities is that users tend to be generous when assigning memory to their VMs. Here are some memory sizing practices we’ve heard from customers:   ·         I assign 4 GB of memory to my VMs. I don’t know if all of it is being used by the applications but no one complains. ·         I take the minimum system requirements and add 50% more. ·         I go with the recommendations provided by my software vendor.   In reality correctly sizing a virtual machine requires significant effort to monitor the memory usage of the applications. Since this is not done in most environments, VMs are usually over-provisioned in terms of memory. In other words, a SQL Server VM that is assigned 4 GB of memory may not need to use 4 GB.   How does Dynamic Memory help?   Dynamic Memory improves the memory utilization by removing the requirement to determine the memory need for an application. Hyper-V determines the memory needed by applications in the VM by evaluating the memory usage information in the guest with Dynamic Memory. VMs can start with a small amount of memory and they can be assigned more memory dynamically based on the workload of applications running inside.   Overview of Dynamic Memory Concepts   ·         Startup Memory: Startup Memory is the starting amount of memory when Dynamic Memory is enabled for a VM. Dynamic Memory will make sure that this amount of memory is always assigned to the VMs by default.   ·         Maximum Memory: Maximum Memory specifies the maximum amount of memory that a VM can grow to with Dynamic Memory. ·         Memory Demand: Memory Demand is the amount determined by Dynamic Memory as the memory needed by the applications in the VM. In Windows Server 2008 R2 SP1, this is equal to the total amount of committed memory of the VM. ·         Memory Buffer: Memory Buffer is the amount of memory assigned to the VMs in addition to their memory demand to satisfy immediate memory requirements and file cache needs.   Once Dynamic Memory is enabled for a VM, it will start with the “Startup Memory”. After the boot process Dynamic Memory will determine the “Memory Demand” of the VM. Based on this memory demand it will determine the amount of “Memory Buffer” that needs to be assigned to the VM. Dynamic Memory will assign the total of “Memory Demand” and “Memory Buffer” to the VM as long as this value is less than “Maximum Memory” and as long as physical memory is available on the host.   What happens when there is not enough physical memory available on the host?   Once there is not enough physical memory on the host to satisfy VM needs, Dynamic Memory will assign less than needed amount of memory to the VMs based on their importance. A concept known as “Memory Weight” is used to determine how much VMs should be penalized based on their needed amount of memory. “Memory Weight” is a configuration setting on the VM. It can be configured to be higher for the VMs with high performance requirements. Under high memory pressure on the host, the “Memory Weight” of the VMs are evaluated in a relative manner and the VMs with lower relative “Memory Weight” will be penalized more than the ones with higher “Memory Weight”.   Dynamic Memory Configuration   Based on these concepts “Startup Memory”, “Maximum Memory”, “Memory Buffer” and “Memory Weight” can be configured as shown below in Windows Server 2008 R2 SP1 Hyper-V Manager. Memory Demand is automatically calculated by Dynamic Memory once VMs start running.     Dynamic Memory Monitoring    In Windows Server 2008 R2 SP1, Hyper-V Manager displays the memory status of VMs in the following three columns:         ·         Assigned Memory represents the current physical memory assigned to the VM. In regular conditions this will be equal to the sum of “Memory Demand” and “Memory Buffer” assigned to the VM. When there is not enough memory on the host, this value can go below the Memory Demand determined for the VM. ·         Memory Demand displays the current “Memory Demand” determined for the VM. ·         Memory Status displays the current memory status of the VM. This column can represent three values for a VM: o   OK: In this condition the VM is assigned the total of Memory Demand and Memory Buffer it needs. o   Low: In this condition the VM is assigned all the Memory Demand and a certain percentage of the Memory Buffer it needs. o   Warning: In this condition the VM is assigned a lower memory than its Memory Demand. When VMs are running in this condition, it’s likely that they will exhibit performance problems due to internal paging happening in the VM.    So far so good! But how does it work with SQL Server?   SQL Server is aggressive in terms of memory usage for good reasons. This raises the question: How do SQL Server and Dynamic Memory work together? To understand the full story, we’ll first need to understand how SQL Server Memory Management works. This will be covered in our second post in “SQL and Dynamic Memory” series. Meanwhile if you want to dive deeper into Dynamic Memory you can check the below posts from the Windows Virtualization Team Blog:   http://blogs.technet.com/virtualization/archive/2010/03/18/dynamic-memory-coming-to-hyper-v.aspx   http://blogs.technet.com/virtualization/archive/2010/03/25/dynamic-memory-coming-to-hyper-v-part-2.aspx   http://blogs.technet.com/virtualization/archive/2010/04/07/dynamic-memory-coming-to-hyper-v-part-3.aspx   http://blogs.technet.com/b/virtualization/archive/2010/04/21/dynamic-memory-coming-to-hyper-v-part-4.aspx   http://blogs.technet.com/b/virtualization/archive/2010/05/20/dynamic-memory-coming-to-hyper-v-part-5.aspx   http://blogs.technet.com/b/virtualization/archive/2010/07/12/dynamic-memory-coming-to-hyper-v-part-6.aspx   - Serdar Sutay   Originally posted at http://blogs.msdn.com/b/sqlosteam/

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  • SQL Server and Hyper-V Dynamic Memory - Part 1

    - by SQLOS Team
    SQL and Dynamic Memory Blog Post Series   Hyper-V Dynamic Memory is a new feature in Windows Server 2008 R2 SP1 that allows the memory assigned to guest virtual machines to vary according to demand. Using this feature with SQL Server is supported, but how well does it work in an environment where available memory can vary dynamically, especially since SQL Server likes memory, and is not very eager to let go of it? The next three posts will look at this question in detail. In Part 1 Serdar Sutay, a program manager in the Windows Hyper-V team, introduces Dynamic Memory with an overview of the basic architecture, configuration and monitoring concepts. In subsequent parts we will look at SQL Server memory handling, and develop some guidelines on using SQL Server with Dynamic Memory.   Part 1: Dynamic Memory Introduction   In virtualized environments memory is often the bottleneck for reaching higher VM densities. In Windows Server 2008 R2 SP1 Hyper-V introduced a new feature “Dynamic Memory” to improve VM densities on Hyper-V hosts. Dynamic Memory increases the memory utilization in virtualized environments by enabling VM memory to be changed dynamically when the VM is running.   This brings up the question of how to utilize this feature with SQL Server VMs as SQL Server performance is very sensitive to the memory being used. In the next three posts we’ll discuss the internals of Dynamic Memory, SQL Server Memory Management and how to use Dynamic Memory with SQL Server VMs.   Memory Utilization Efficiency in Virtualized Environments   The primary reason memory is usually the bottleneck for higher VM densities is that users tend to be generous when assigning memory to their VMs. Here are some memory sizing practices we’ve heard from customers:   ·         I assign 4 GB of memory to my VMs. I don’t know if all of it is being used by the applications but no one complains. ·         I take the minimum system requirements and add 50% more. ·         I go with the recommendations provided by my software vendor.   In reality correctly sizing a virtual machine requires significant effort to monitor the memory usage of the applications. Since this is not done in most environments, VMs are usually over-provisioned in terms of memory. In other words, a SQL Server VM that is assigned 4 GB of memory may not need to use 4 GB.   How does Dynamic Memory help?   Dynamic Memory improves the memory utilization by removing the requirement to determine the memory need for an application. Hyper-V determines the memory needed by applications in the VM by evaluating the memory usage information in the guest with Dynamic Memory. VMs can start with a small amount of memory and they can be assigned more memory dynamically based on the workload of applications running inside.   Overview of Dynamic Memory Concepts   ·         Startup Memory: Startup Memory is the starting amount of memory when Dynamic Memory is enabled for a VM. Dynamic Memory will make sure that this amount of memory is always assigned to the VMs by default.   ·         Maximum Memory: Maximum Memory specifies the maximum amount of memory that a VM can grow to with Dynamic Memory. ·         Memory Demand: Memory Demand is the amount determined by Dynamic Memory as the memory needed by the applications in the VM. In Windows Server 2008 R2 SP1, this is equal to the total amount of committed memory of the VM. ·         Memory Buffer: Memory Buffer is the amount of memory assigned to the VMs in addition to their memory demand to satisfy immediate memory requirements and file cache needs.   Once Dynamic Memory is enabled for a VM, it will start with the “Startup Memory”. After the boot process Dynamic Memory will determine the “Memory Demand” of the VM. Based on this memory demand it will determine the amount of “Memory Buffer” that needs to be assigned to the VM. Dynamic Memory will assign the total of “Memory Demand” and “Memory Buffer” to the VM as long as this value is less than “Maximum Memory” and as long as physical memory is available on the host.   What happens when there is not enough physical memory available on the host?   Once there is not enough physical memory on the host to satisfy VM needs, Dynamic Memory will assign less than needed amount of memory to the VMs based on their importance. A concept known as “Memory Weight” is used to determine how much VMs should be penalized based on their needed amount of memory. “Memory Weight” is a configuration setting on the VM. It can be configured to be higher for the VMs with high performance requirements. Under high memory pressure on the host, the “Memory Weight” of the VMs are evaluated in a relative manner and the VMs with lower relative “Memory Weight” will be penalized more than the ones with higher “Memory Weight”.   Dynamic Memory Configuration   Based on these concepts “Startup Memory”, “Maximum Memory”, “Memory Buffer” and “Memory Weight” can be configured as shown below in Windows Server 2008 R2 SP1 Hyper-V Manager. Memory Demand is automatically calculated by Dynamic Memory once VMs start running.     Dynamic Memory Monitoring    In Windows Server 2008 R2 SP1, Hyper-V Manager displays the memory status of VMs in the following three columns:         ·         Assigned Memory represents the current physical memory assigned to the VM. In regular conditions this will be equal to the sum of “Memory Demand” and “Memory Buffer” assigned to the VM. When there is not enough memory on the host, this value can go below the Memory Demand determined for the VM. ·         Memory Demand displays the current “Memory Demand” determined for the VM. ·         Memory Status displays the current memory status of the VM. This column can represent three values for a VM: o   OK: In this condition the VM is assigned the total of Memory Demand and Memory Buffer it needs. o   Low: In this condition the VM is assigned all the Memory Demand and a certain percentage of the Memory Buffer it needs. o   Warning: In this condition the VM is assigned a lower memory than its Memory Demand. When VMs are running in this condition, it’s likely that they will exhibit performance problems due to internal paging happening in the VM.    So far so good! But how does it work with SQL Server?   SQL Server is aggressive in terms of memory usage for good reasons. This raises the question: How do SQL Server and Dynamic Memory work together? To understand the full story, we’ll first need to understand how SQL Server Memory Management works. This will be covered in our second post in “SQL and Dynamic Memory” series. Meanwhile if you want to dive deeper into Dynamic Memory you can check the below posts from the Windows Virtualization Team Blog:   http://blogs.technet.com/virtualization/archive/2010/03/18/dynamic-memory-coming-to-hyper-v.aspx   http://blogs.technet.com/virtualization/archive/2010/03/25/dynamic-memory-coming-to-hyper-v-part-2.aspx   http://blogs.technet.com/virtualization/archive/2010/04/07/dynamic-memory-coming-to-hyper-v-part-3.aspx   http://blogs.technet.com/b/virtualization/archive/2010/04/21/dynamic-memory-coming-to-hyper-v-part-4.aspx   http://blogs.technet.com/b/virtualization/archive/2010/05/20/dynamic-memory-coming-to-hyper-v-part-5.aspx   http://blogs.technet.com/b/virtualization/archive/2010/07/12/dynamic-memory-coming-to-hyper-v-part-6.aspx   - Serdar Sutay   Originally posted at http://blogs.msdn.com/b/sqlosteam/

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  • SQL Server and Hyper-V Dynamic Memory Part 3

    - by SQLOS Team
    In parts 1 and 2 of this series we looked at the basics of Hyper-V Dynamic Memory and SQL Server memory management. In this part Serdar looks at configuration guidelines for SQL Server memory management. Part 3: Configuration Guidelines for Hyper-V Dynamic Memory and SQL Server Now that we understand SQL Server Memory Management and Hyper-V Dynamic Memory basics, let’s take a look at general configuration guidelines in order to utilize benefits of Hyper-V Dynamic Memory in your SQL Server VMs. Requirements Host Operating System Requirements Hyper-V Dynamic Memory feature is introduced with Windows Server 2008 R2 SP1. Therefore in order to use Dynamic Memory for your virtual machines, you need to have Windows Server 2008 R2 SP1 or Microsoft Hyper-V Server 2008 R2 SP1 in your Hyper-V host. Guest Operating System Requirements In addition to this Dynamic Memory is only supported in Standard, Web, Enterprise and Datacenter editions of windows running inside VMs. Make sure that your VM is running one of these editions. For additional requirements on each operating system see “Dynamic Memory Configuration Guidelines” here. SQL Server Requirements All versions of SQL Server support Hyper-V Dynamic Memory. However, only certain editions of SQL Server are aware of dynamically changing system memory. To have a truly dynamic environment for your SQL Server VMs make sure that you are running one of the SQL Server editions listed below: ·         SQL Server 2005 Enterprise ·         SQL Server 2008 Enterprise / Datacenter Editions ·         SQL Server 2008 R2 Enterprise / Datacenter Editions Configuration guidelines for other versions of SQL Server are covered below in the FAQ section. Guidelines for configuring Dynamic Memory Parameters Here is how to configure Dynamic Memory for your SQL VMs in a nutshell: Hyper-V Dynamic Memory Parameter Recommendation Startup RAM 1 GB + SQL Min Server Memory Maximum RAM > SQL Max Server Memory Memory Buffer % 5 Memory Weight Based on performance needs   Startup RAM In order to ensure that your SQL Server VMs can start correctly, ensure that Startup RAM is higher than configured SQL Min Server Memory for your VMs. Otherwise SQL Server service will need to do paging in order to start since it will not be able to see enough memory during startup. Also note that Startup Memory will always be reserved for your VMs. This will guarantee a certain level of performance for your SQL Servers, however setting this too high will limit the consolidation benefits you’ll get out of your virtualization environment. Maximum RAM This one is obvious. If you’ve configured SQL Max Server Memory for your SQL Server, make sure that Dynamic Memory Maximum RAM configuration is higher than this value. Otherwise your SQL Server will not grow to memory values higher than the value configured for Dynamic Memory. Memory Buffer % Memory buffer configuration is used to provision file cache to virtual machines in order to improve performance. Due to the fact that SQL Server is managing its own buffer pool, Memory Buffer setting should be configured to the lowest value possible, 5%. Configuring a higher memory buffer will prevent low resource notifications from Windows Memory Manager and it will prevent reclaiming memory from SQL Server VMs. Memory Weight Memory weight configuration defines the importance of memory to a VM. Configure higher values for the VMs that have higher performance requirements. VMs with higher memory weight will have more memory under high memory pressure conditions on your host. Questions and Answers Q1 – Which SQL Server memory model is best for Dynamic Memory? The best SQL Server model for Dynamic Memory is “Locked Page Memory Model”. This memory model ensures that SQL Server memory is never paged out and it’s also adaptive to dynamically changing memory in the system. This will be extremely useful when Dynamic Memory is attempting to remove memory from SQL Server VMs ensuring no SQL Server memory is paged out. You can find instructions on configuring “Locked Page Memory Model” for your SQL Servers here. Q2 – What about other SQL Server Editions, how should I configure Dynamic Memory for them? Other editions of SQL Server do not adapt to dynamically changing environments. They will determine how much memory they should allocate during startup and don’t change this value afterwards. Therefore make sure that you configure a higher startup memory for your VM because that will be all the memory that SQL Server utilize Tune Maximum Memory and Memory Buffer based on the other workloads running on the system. If there are no other workloads consider using Static Memory for these editions. Q3 – What if I have multiple SQL Server instances in a VM? Having multiple SQL Server instances in a VM is not a general recommendation for predictable performance, manageability and isolation. In order to achieve a predictable behavior make sure that you configure SQL Min Server Memory and SQL Max Server Memory for each instance in the VM. And make sure that: ·         Dynamic Memory Startup Memory is greater than the sum of SQL Min Server Memory values for the instances in the VM ·         Dynamic Memory Maximum Memory is greater than the sum of SQL Max Server Memory values for the instances in the VM Q4 – I’m using Large Page Memory Model for my SQL Server. Can I still use Dynamic Memory? The short answer is no. SQL Server does not dynamically change its memory size when configured with Large Page Memory Model. In virtualized environments Hyper-V provides large page support by default. Most of the time, Large Page Memory Model doesn’t bring any benefits to a SQL Server if it’s running in virtualized environments. Q5 – How do I monitor SQL performance when I’m trying Dynamic Memory on my VMs? Use the performance counters below to monitor memory performance for SQL Server: Process - Working Set: This counter is available in the VM via process performance counters. It represents the actual amount of physical memory being used by SQL Server process in the VM. SQL Server – Buffer Cache Hit Ratio: This counter is available in the VM via SQL Server counters. This represents the paging being done by SQL Server. A rate of 90% or higher is desirable. Conclusion These blog posts are a quick start to a story that will be developing more in the near future. We’re still continuing our testing and investigations to provide more detailed configuration guidelines with example performance numbers with a white paper in the upcoming months. Now it’s time to give SQL Server and Hyper-V Dynamic Memory a try. Use this guidelines to kick-start your environment. See what you think about it and let us know of your experiences. - Serdar Sutay Originally posted at http://blogs.msdn.com/b/sqlosteam/

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  • SQL Server 2012 Memory Manager KB articles

    - by SQLOS Team
    Since the release of SQL Server 2012 with a redesigned memory manager, a steady stream of KB articles have been produced by CSS to provide guidance on the new or changed options, as well as fixes that have been published..   How has memory sizing changed in SQL 2012? 2663912 Memory configuration and sizing considerations in SQL Server 2012 - http://support.microsoft.com/default.aspx?scid=kb;EN-US;2663912     Setting "locked pages" to avoid SQL Server memory pages getting swapped has been simplified, particularly for Standard Edition, the details can be found here: 2659143 How to enable the "locked pages" feature in SQL Server 2012 - http://support.microsoft.com/default.aspx?scid=kb;EN-US;2659143   Note the following deprecation (particularly relevant for 32-bit installations): 2644592 The "AWE enabled" SQL Server feature is deprecated - http://support.microsoft.com/default.aspx?scid=kb;EN-US;2644592   Note the following fixes available: 2708594 FIX: Locked page allocations are enabled without any warning after you upgrade to SQL Server 2012 - http://support.microsoft.com/kb/2708594/EN-US 2688697 FIX: Out-of-memory error when you run an instance of SQL Server 2012 on a computer that uses NUMA - http://support.microsoft.com/kb/2688697/EN-US Originally posted at http://blogs.msdn.com/b/sqlosteam/

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  • SQL Server 2012 Memory Manager KB articles

    - by SQLOS Team
    Since the release of SQL Server 2012 with a redesigned memory manager, a steady stream of KB articles have been produced by CSS to provide guidance on the new or changed options, as well as fixes that have been published..   How has memory sizing changed in SQL 2012? 2663912 Memory configuration and sizing considerations in SQL Server 2012 - http://support.microsoft.com/default.aspx?scid=kb;EN-US;2663912     Setting "locked pages" to avoid SQL Server memory pages getting swapped has been simplified, particularly for Standard Edition, the details can be found here: 2659143 How to enable the "locked pages" feature in SQL Server 2012 - http://support.microsoft.com/default.aspx?scid=kb;EN-US;2659143   Note the following deprecation (particularly relevant for 32-bit installations): 2644592 The "AWE enabled" SQL Server feature is deprecated - http://support.microsoft.com/default.aspx?scid=kb;EN-US;2644592   Note the following fixes available: 2708594 FIX: Locked page allocations are enabled without any warning after you upgrade to SQL Server 2012 - http://support.microsoft.com/kb/2708594/EN-US 2688697 FIX: Out-of-memory error when you run an instance of SQL Server 2012 on a computer that uses NUMA - http://support.microsoft.com/kb/2688697/EN-US Originally posted at http://blogs.msdn.com/b/sqlosteam/

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  • Windows Azure Virtual Machine Readiness and Capacity Assessment for SQL Server

    - by SQLOS Team
    Windows Azure Virtual Machine Readiness and Capacity Assessment for Windows Server Machine Running SQL Server With the release of MAP Toolkit 8.0 Beta, we have added a new scenario to assess your Windows Azure Virtual Machine Readiness. The MAP 8.0 Beta performs a comprehensive assessment of Windows Servers running SQL Server to determine you level of readiness to migrate an on-premise physical or virtual machine to Windows Azure Virtual Machines. The MAP Toolkit then offers suggested changes to prepare the machines for migration, such as upgrading the operating system or SQL Server. MAP Toolkit 8.0 Beta is available for download here Your participation and feedback is very important to make the MAP Toolkit work better for you. We encourage you to participate in the beta program and provide your feedback at [email protected] or through one of our surveys. Now, let’s walk through the MAP Toolkit task for completing the Windows Azure Virtual Machine assessment and capacity planning. The tasks include the following: Perform an inventory View the Windows Azure VM Readiness results and report Collect performance data for determine VM sizing View the Windows Azure Capacity results and report Perform an inventory: 1. To perform an inventory against a single machine or across a complete environment, choose Perform an Inventory to launch the Inventory and Assessment Wizard as shown below: 2. After the Inventory and Assessment Wizard launches, select either the Windows computers or SQL Server scenario to inventory Windows machines. HINT: If you don’t care about completely inventorying a machine, just select the SQL Server scenario. Click Next to Continue. 3. On the Discovery Methods page, select how you want to discover computers and then click Next to continue. Description of Discovery Methods: Use Active Directory Domain Services -- This method allows you to query a domain controller via the Lightweight Directory Access Protocol (LDAP) and select computers in all or specific domains, containers, or OUs. Use this method if all computers and devices are in AD DS. Windows networking protocols --  This method uses the WIN32 LAN Manager application programming interfaces to query the Computer Browser service for computers in workgroups and Windows NT 4.0–based domains. If the computers on the network are not joined to an Active Directory domain, use only the Windows networking protocols option to find computers. System Center Configuration Manager (SCCM) -- This method enables you to inventory computers managed by System Center Configuration Manager (SCCM). You need to provide credentials to the System Center Configuration Manager server in order to inventory the managed computers. When you select this option, the MAP Toolkit will query SCCM for a list of computers and then MAP will connect to these computers. Scan an IP address range -- This method allows you to specify the starting address and ending address of an IP address range. The wizard will then scan all IP addresses in the range and inventory only those computers. Note: This option can perform poorly, if many IP addresses aren’t being used within the range. Manually enter computer names and credentials -- Use this method if you want to inventory a small number of specific computers. Import computer names from a files -- Using this method, you can create a text file with a list of computer names that will be inventoried. 4. On the All Computers Credentials page, enter the accounts that have administrator rights to connect to the discovered machines. This does not need to a domain account, but needs to be a local administrator. I have entered my domain account that is an administrator on my local machine. Click Next after one or more accounts have been added. NOTE: The MAP Toolkit primarily uses Windows Management Instrumentation (WMI) to collect hardware, device, and software information from the remote computers. In order for the MAP Toolkit to successfully connect and inventory computers in your environment, you have to configure your machines to inventory through WMI and also allow your firewall to enable remote access through WMI. The MAP Toolkit also requires remote registry access for certain assessments. In addition to enabling WMI, you need accounts with administrative privileges to access desktops and servers in your environment. 5. On the Credentials Order page, select the order in which want the MAP Toolkit to connect to the machine and SQL Server. Generally just accept the defaults and click Next. 6. On the Enter Computers Manually page, click Create to pull up at dialog to enter one or more computer names. 7. On the Summary page confirm your settings and then click Finish. After clicking Finish the inventory process will start, as shown below: Windows Azure Readiness results and report After the inventory progress has completed, you can review the results under the Database scenario. On the tile, you will see the number of Windows Server machine with SQL Server that were analyzed, the number of machines that are ready to move without changes and the number of machines that require further changes. If you click this Azure VM Readiness tile, you will see additional details and can generate the Windows Azure VM Readiness Report. After the report is generated, select View | Saved Reports and Proposals to view the location of the report. Open up WindowsAzureVMReadiness* report in Excel. On the Windows tab, you can see the results of the assessment. This report has a column for the Operating System and SQL Server assessment and provides a recommendation on how to resolve, if there a component is not supported. Collect Performance Data Launch the Performance Wizard to collect performance information for the Windows Server machines that you would like the MAP Toolkit to suggest a Windows Azure VM size for. Windows Azure Capacity results and report After the performance metrics are collected, the Azure VM Capacity title will display the number of Virtual Machine sizes that are suggested for the Windows Server and Linux machines that were analyzed. You can then click on the Azure VM Capacity tile to see the capacity details and generate the Windows Azure VM Capacity Report. Within this report, you can view the performance data that was collected and the Virtual Machine sizes.   MAP Toolkit 8.0 Beta is available for download here Your participation and feedback is very important to make the MAP Toolkit work better for you. We encourage you to participate in the beta program and provide your feedback at [email protected] or through one of our surveys. Useful References: Windows Azure Homepage How to guides for Windows Azure Virtual Machines Provisioning a SQL Server Virtual Machine on Windows Azure Windows Azure Pricing     Peter Saddow Senior Program Manager – MAP Toolkit Team

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  • Better documentation for tasks waiting on resources

    - by SQLOS Team
    The sys.dm_os_waiting_tasks DMV contains a wealth of useful information about tasks waiting on a resource, but until now detailed information about the resource being consumed - sys.dm_os_waiting_tasks.resource_description - hasn't been documented, apart from a rather self-evident "Description of the resource that is being consumed."   Thanks to a recent Connect suggestion this column will get more information added. Here is a summary of the possible values that can appear in this column - Note this information is current for SQL Server 2008 R2 and Denali:   Thread-pool resource owner:•       threadpool id=scheduler<hex-address> Parallel query resource owner:•       exchangeEvent id={Port|Pipe}<hex-address> WaitType=<exchange-wait-type> nodeId=<exchange-node-id> Exchange-wait-type can be one of the following.•       e_waitNone•       e_waitPipeNewRow•       e_waitPipeGetRow•       e_waitSynchronizeConsumerOpen•       e_waitPortOpen•       e_waitPortClose•       e_waitRange Lock resource owner:<type-specific-description> id=lock<lock-hex-address> mode=<mode> associatedObjectId=<associated-obj-id>               <type-specific-description> can be:• For DATABASE: databaselock subresource=<databaselock-subresource> dbid=<db-id>• For FILE: filelock fileid=<file-id> subresource=<filelock-subresource> dbid=<db-id>• For OBJECT: objectlock lockPartition=<lock-partition-id> objid=<obj-id> subresource=<objectlock-subresource> dbid=<db-id>• For PAGE: pagelock fileid=<file-id> pageid=<page-id> dbid=<db-id> subresource=<pagelock-subresource>• For Key: keylock  hobtid=<hobt-id> dbid=<db-id>• For EXTENT: extentlock fileid=<file-id> pageid=<page-id> dbid=<db-id>• For RID: ridlock fileid=<file-id> pageid=<page-id> dbid=<db-id>• For APPLICATION: applicationlock hash=<hash> databasePrincipalId=<role-id> dbid=<db-id>• For METADATA: metadatalock subresource=<metadata-subresource> classid=<metadatalock-description> dbid=<db-id>• For HOBT: hobtlock hobtid=<hobt-id> subresource=<hobt-subresource> dbid=<db-id>• For ALLOCATION_UNIT: allocunitlock hobtid=<hobt-id> subresource=<alloc-unit-subresource> dbid=<db-id> <mode> can be:• Sch-S• Sch-M• S• U• X• IS• IU• IX• SIU• SIX• UIX• BU• RangeS-S• RangeS-U• RangeI-N• RangeI-S• RangeI-U• RangeI-X• RangeX-S• RangeX-U• RangeX-X External resource owner:•       External ExternalResource=<wait-type> Generic resource owner:•       TransactionMutex TransactionInfo Workspace=<workspace-id>•       Mutex•       CLRTaskJoin•       CLRMonitorEvent•       CLRRWLockEvent•       resourceWait Latch resource owner:•       <db-id>:<file-id>:<page-in-file>•       <GUID>•       <latch-class> (<latch-address>)   Further Information Slava Oks's weblog: sys.dm_os_waiting_tasks.Informit.com: Identifying Blocking Using sys.dm_os_waiting_tasks - Ken Henderson   - Guy

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  • Manage SQL Server Connectivity through Windows Azure Virtual Machines Remote PowerShell

    - by SQLOS Team
    Manage SQL Server Connectivity through Windows Azure Virtual Machines Remote PowerShell Blog This blog post comes from Khalid Mouss, Senior Program Manager in Microsoft SQL Server. Overview The goal of this blog is to demonstrate how we can automate through PowerShell connecting multiple SQL Server deployments in Windows Azure Virtual Machines. We would configure TCP port that we would open (and close) though Windows firewall from a remote PowerShell session to the Virtual Machine (VM). This will demonstrate how to take the advantage of the remote PowerShell support in Windows Azure Virtual Machines to automate the steps required to connect SQL Server in the same cloud service and in different cloud services.  Scenario 1: VMs connected through the same Cloud Service 2 Virtual machines configured in the same cloud service. Both VMs running different SQL Server instances on them. Both VMs configured with remote PowerShell turned on to be able to run PS and other commands directly into them remotely in order to re-configure them to allow incoming SQL connections from a remote VM or on premise machine(s). Note: RDP (Remote Desktop Protocol) is kept configured in both VMs by default to be able to remote connect to them and check the connections to SQL instances for demo purposes only; but not actually required. Step 1 – Provision VMs and Configure Ports   Provision VM1; named DemoVM1 as follows (see examples screenshots below if using the portal):   Provision VM2 (DemoVM2) with PowerShell Remoting enabled and connected to DemoVM1 above (see examples screenshots below if using the portal): After provisioning of the 2 VMs above, here is the default port configurations for example: Step2 – Verify / Confirm the TCP port used by the database Engine By the default, the port will be configured to be 1433 – this can be changed to a different port number if desired.   1. RDP to each of the VMs created below – this will also ensure the VMs complete SysPrep(ing) and complete configuration 2. Go to SQL Server Configuration Manager -> SQL Server Network Configuration -> Protocols for <SQL instance> -> TCP/IP - > IP Addresses   3. Confirm the port number used by SQL Server Engine; in this case 1433 4. Update from Windows Authentication to Mixed mode   5.       Restart SQL Server service for the change to take effect 6.       Repeat steps 3., 4., and 5. For the second VM: DemoVM2 Step 3 – Remote Powershell to DemoVM1 Enter-PSSession -ComputerName condemo.cloudapp.net -Port 61503 -Credential <username> -UseSSL -SessionOption (New-PSSessionOption -SkipCACheck -SkipCNCheck) Your will then be prompted to enter the password. Step 4 – Open 1433 port in the Windows firewall netsh advfirewall firewall add rule name="DemoVM1Port" dir=in localport=1433 protocol=TCP action=allow Output: netsh advfirewall firewall show rule name=DemoVM1Port Rule Name:                            DemoVM1Port ---------------------------------------------------------------------- Enabled:                              Yes Direction:                            In Profiles:                             Domain,Private,Public Grouping:                             LocalIP:                              Any RemoteIP:                             Any Protocol:                             TCP LocalPort:                            1433 RemotePort:                           Any Edge traversal:                       No Action:                               Allow Ok. Step 5 – Now connect from DemoVM2 to DB instance in DemoVM1 Step 6 – Close port 1433 in the Windows firewall netsh advfirewall firewall delete rule name=DemoVM1Port Output: Deleted 1 rule(s). Ok. netsh advfirewall firewall show  rule name=DemoVM1Port No rules match the specified criteria.   Step 7 – Try to connect from DemoVM2 to DB Instance in DemoVM1  Because port 1433 has been closed (in step 6) in the Windows Firewall in VM1 machine, we can longer connect from VM3 remotely to VM1. Scenario 2: VMs provisioned in different Cloud Services 2 Virtual machines configured in different cloud services. Both VMs running different SQL Server instances on them. Both VMs configured with remote PowerShell turned on to be able to run PS and other commands directly into them remotely in order to re-configure them to allow incoming SQL connections from a remote VM or on on-premise machine(s). Note: RDP (Remote Desktop Protocol) is kept configured in both VMs by default to be able to remote connect to them and check the connections to SQL instances for demo purposes only; but not actually needed. Step 1 – Provision new VM3 Provision VM3; named DemoVM3 as follows (see examples screenshots below if using the portal): After provisioning is complete, here is the default port configurations: Step 2 – Add public port to VM1 connect to from VM3’s DB instance Since VM3 and VM1 are not connected in the same cloud service, we will need to specify the full DNS address while connecting between the machines which includes the public port. We shall add a public port 57000 in this case that is linked to private port 1433 which will be used later to connect to the DB instance. Step 3 – Remote Powershell to DemoVM1 Enter-PSSession -ComputerName condemo.cloudapp.net -Port 61503 -Credential <UserName> -UseSSL -SessionOption (New-PSSessionOption -SkipCACheck -SkipCNCheck) You will then be prompted to enter the password.   Step 4 – Open 1433 port in the Windows firewall netsh advfirewall firewall add rule name="DemoVM1Port" dir=in localport=1433 protocol=TCP action=allow Output: Ok. netsh advfirewall firewall show rule name=DemoVM1Port Rule Name:                            DemoVM1Port ---------------------------------------------------------------------- Enabled:                              Yes Direction:                            In Profiles:                             Domain,Private,Public Grouping:                             LocalIP:                              Any RemoteIP:                             Any Protocol:                             TCP LocalPort:                            1433 RemotePort:                           Any Edge traversal:                       No Action:                               Allow Ok.   Step 5 – Now connect from DemoVM3 to DB instance in DemoVM1 RDP into VM3, launch SSM and Connect to VM1’s DB instance as follows. You must specify the full server name using the DNS address and public port number configured above. Step 6 – Close port 1433 in the Windows firewall netsh advfirewall firewall delete rule name=DemoVM1Port   Output: Deleted 1 rule(s). Ok. netsh advfirewall firewall show  rule name=DemoVM1Port No rules match the specified criteria.  Step 7 – Try to connect from DemoVM2 to DB Instance in DemoVM1  Because port 1433 has been closed (in step 6) in the Windows Firewall in VM1 machine, we can no longer connect from VM3 remotely to VM1. Conclusion Through the new support for remote PowerShell in Windows Azure Virtual Machines, one can script and automate many Virtual Machine and SQL management tasks. In this blog, we have demonstrated, how to start a remote PowerShell session, re-configure Virtual Machine firewall to allow (or disallow) SQL Server connections. References SQL Server in Windows Azure Virtual Machines   Originally posted at http://blogs.msdn.com/b/sqlosteam/

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  • SQL Server 2014 CTP1 now available for download as well as in Windows Azure Image Gallery

    - by SQLOS Team
    Exciting news - At TechEd Europe 2013 keynote today, we announced that SQL Server 2014 CTP1 is now available for download as well as in Windows Azure Image Gallery. Try it out now and give us feedback. http://www.microsoft.com/en-us/sqlserver/sql-server-2014.aspx http://europe.msteched.com/#fbid=bdRdsIPwIgn - Watch the Keynote again   thanks, Madhan     Originally posted at http://blogs.msdn.com/b/sqlosteam/

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  • Windows Azure Virtual Machine Readiness and Capacity Assessment for SQL Server

    - by SQLOS Team
    Windows Azure Virtual Machine Readiness and Capacity Assessment for Windows Server Machine Running SQL Server With the release of MAP Toolkit 8.0 Beta, we have added a new scenario to assess your Windows Azure Virtual Machine Readiness. The MAP 8.0 Beta performs a comprehensive assessment of Windows Servers running SQL Server to determine you level of readiness to migrate an on-premise physical or virtual machine to Windows Azure Virtual Machines. The MAP Toolkit then offers suggested changes to prepare the machines for migration, such as upgrading the operating system or SQL Server. MAP Toolkit 8.0 Beta is available for download here Your participation and feedback is very important to make the MAP Toolkit work better for you. We encourage you to participate in the beta program and provide your feedback at [email protected] or through one of our surveys. Now, let’s walk through the MAP Toolkit task for completing the Windows Azure Virtual Machine assessment and capacity planning. The tasks include the following: Perform an inventory View the Windows Azure VM Readiness results and report Collect performance data for determine VM sizing View the Windows Azure Capacity results and report Perform an inventory: 1. To perform an inventory against a single machine or across a complete environment, choose Perform an Inventory to launch the Inventory and Assessment Wizard as shown below: 2. After the Inventory and Assessment Wizard launches, select either the Windows computers or SQL Server scenario to inventory Windows machines. HINT: If you don’t care about completely inventorying a machine, just select the SQL Server scenario. Click Next to Continue. 3. On the Discovery Methods page, select how you want to discover computers and then click Next to continue. Description of Discovery Methods: Use Active Directory Domain Services -- This method allows you to query a domain controller via the Lightweight Directory Access Protocol (LDAP) and select computers in all or specific domains, containers, or OUs. Use this method if all computers and devices are in AD DS. Windows networking protocols --  This method uses the WIN32 LAN Manager application programming interfaces to query the Computer Browser service for computers in workgroups and Windows NT 4.0–based domains. If the computers on the network are not joined to an Active Directory domain, use only the Windows networking protocols option to find computers. System Center Configuration Manager (SCCM) -- This method enables you to inventory computers managed by System Center Configuration Manager (SCCM). You need to provide credentials to the System Center Configuration Manager server in order to inventory the managed computers. When you select this option, the MAP Toolkit will query SCCM for a list of computers and then MAP will connect to these computers. Scan an IP address range -- This method allows you to specify the starting address and ending address of an IP address range. The wizard will then scan all IP addresses in the range and inventory only those computers. Note: This option can perform poorly, if many IP addresses aren’t being used within the range. Manually enter computer names and credentials -- Use this method if you want to inventory a small number of specific computers. Import computer names from a files -- Using this method, you can create a text file with a list of computer names that will be inventoried. 4. On the All Computers Credentials page, enter the accounts that have administrator rights to connect to the discovered machines. This does not need to a domain account, but needs to be a local administrator. I have entered my domain account that is an administrator on my local machine. Click Next after one or more accounts have been added. NOTE: The MAP Toolkit primarily uses Windows Management Instrumentation (WMI) to collect hardware, device, and software information from the remote computers. In order for the MAP Toolkit to successfully connect and inventory computers in your environment, you have to configure your machines to inventory through WMI and also allow your firewall to enable remote access through WMI. The MAP Toolkit also requires remote registry access for certain assessments. In addition to enabling WMI, you need accounts with administrative privileges to access desktops and servers in your environment. 5. On the Credentials Order page, select the order in which want the MAP Toolkit to connect to the machine and SQL Server. Generally just accept the defaults and click Next. 6. On the Enter Computers Manually page, click Create to pull up at dialog to enter one or more computer names. 7. On the Summary page confirm your settings and then click Finish. After clicking Finish the inventory process will start, as shown below: Windows Azure Readiness results and report After the inventory progress has completed, you can review the results under the Database scenario. On the tile, you will see the number of Windows Server machine with SQL Server that were analyzed, the number of machines that are ready to move without changes and the number of machines that require further changes. If you click this Azure VM Readiness tile, you will see additional details and can generate the Windows Azure VM Readiness Report. After the report is generated, select View | Saved Reports and Proposals to view the location of the report. Open up WindowsAzureVMReadiness* report in Excel. On the Windows tab, you can see the results of the assessment. This report has a column for the Operating System and SQL Server assessment and provides a recommendation on how to resolve, if there a component is not supported. Collect Performance Data Launch the Performance Wizard to collect performance information for the Windows Server machines that you would like the MAP Toolkit to suggest a Windows Azure VM size for. Windows Azure Capacity results and report After the performance metrics are collected, the Azure VM Capacity title will display the number of Virtual Machine sizes that are suggested for the Windows Server and Linux machines that were analyzed. You can then click on the Azure VM Capacity tile to see the capacity details and generate the Windows Azure VM Capacity Report. Within this report, you can view the performance data that was collected and the Virtual Machine sizes.   MAP Toolkit 8.0 Beta is available for download here Your participation and feedback is very important to make the MAP Toolkit work better for you. We encourage you to participate in the beta program and provide your feedback at [email protected] or through one of our surveys. Useful References: Windows Azure Homepage How to guides for Windows Azure Virtual Machines Provisioning a SQL Server Virtual Machine on Windows Azure Windows Azure Pricing     Peter Saddow Senior Program Manager – MAP Toolkit Team

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  • What causes Multi-Page allocations?

    - by SQLOS Team
    Writing about changes in the Denali Memory Manager In his last post Rusi mentioned: " In previous SQL versions only the 8k allocations were limited by the ‘max server memory’ configuration option.  Allocations larger than 8k weren’t constrained." In SQL Server versions before Denali single page allocations and multi-Page allocations are handled by different components, the Single Page Allocator (which is responsible for Buffer Pool allocations and governed by 'max server memory') and the Multi-Page allocator (MPA) which handles allocations of greater than an 8K page. If there are many multi-page allocations this can affect how much memory needs to be reserved outside 'max server memory' which may in turn involve setting the -g memory_to_reserve startup parameter. We'll follow up with more generic articles on the new Memory Manager structure, but in this post I want to clarify what might cause these larger allocations. So what kinds of query result in MPA activity? I was asked this question the other day after delivering an MCM webcast on Memory Manager changes in Denali. After asking around our Dev team I was connected to one of our test leads Sangeetha who had tested the plan cache, and kindly provided this example of an MPA intensive query: A workload that has stored procedures with a large # of parameters (say > 100, > 500), and then invoked via large ad hoc batches, where each SP has different parameters will result in a plan being cached for this “exec proc” batch. This plan will result in MPA.   Exec proc_name @p1, ….@p500 Exec proc_name @p1, ….@p500 . . . Exec proc_name @p1, ….@p500 Go   Another workload would be large adhoc batches of the form: Select * from t where col1 in (1, 2, 3, ….500) Select * from t where col1 in (1, 2, 3, ….500) Select * from t where col1 in (1, 2, 3, ….500) … Go  In Denali all page allocations are handled by an "Any size page allocator" and included in 'max server memory'. The buffer pool effectively becomes a client of the any size page allocator, which in turn relies on the memory manager. - Guy Originally posted at http://blogs.msdn.com/b/sqlosteam/

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  • Lock Pages in Memory - not deprecated in Denali

    - by SQLOS Team
    Please note an error in the SQL 2012 documentation for Lock Pages in Memory which indicates that it's deprecated. It's not. Locking pages in memory is a useful feature and there are no plans to deprecate it. It looks like it was accidently included on this page when we made changes to deprecate AWE. So.. keep using it :-) The documentation has been fixed and should appear in Books Online in the next refresh by mid-April. Thanks Guy Originally posted at http://blogs.msdn.com/b/sqlosteam/

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  • SQL Server Memory Manager Changes in Denali

    - by SQLOS Team
    The next version of SQL Server will contain significant changes to the memory manager component.  The memory manager component has been rewritten for Denali.  In the previous versions of SQL Server there were two distinct memory managers.  There was one memory manager which handled allocation sizes of 8k or less and another for greater than 8k.  For Denali there will be one memory manager for all allocation sizes.   The majority of the changes will be transparent to the end user.  However, some changes will be visible to the user.  These are listed below: ·         The ‘max server memory’ configuration option has new lower limits.  Specifically, 32-bit versions of SQL Server will have a lower limit of 64 MB.  The 64-bit versions will have a lower limit of 128 MB. ·         All memory allocations by SQL Server components will observe the ‘max server memory’ configuration option.  In previous SQL versions only the 8k allocations were limited the ‘max server memory’ configuration option.  Allocations larger than 8k weren’t constrained. ·         DMVs which refer to memory manager internals have been modified.  This includes adding or removing columns and changing column names. ·         The memory manager configuration messages in the error log have minor changes. ·         DBCC memorystatus output has been changed. ·         Address Windowing Extensions (AWE) has been deprecated.   In the next blog post I will discuss the changes to the memory manager DMVs in greater detail.  In future blog posts I will discuss the other changes in greater detail.  

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  • SQL Server Operating System

    - by NDeveloper
    Hi, I found an interesting article about Platform layer for SQL Server. It talks about SQLOS. As I understand it is an abstraction layer between the hardware and SQL Server. So does it mean that we can have SQL Server installed without installing windows? It sounds very strange to me... Please tell me where it is possible to find more info on this. And also whoever have used SQLOS and for what reason? What are the main advantages from developers view?

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  • SQLPASS Summit 2011 -- I'm going but not as a speaker

    - by NeilHambly
    This post is about my attempt and slight failure @ getting a presenting session @ this year’s SQLPASS Summit 2011 I had submitted for the 1st time 2 submissions (think we had max of 4 we could enter, but I was happy to go with just 2 this time, 1 I had already presented & 1 was nearly completed) My general session (75 minutes) the same session on “Waits” I had done @ SQLBits 8 back in Brighton last April, and a new 1/2 day 3.5 hours format which is a session I’m completing on SQLOS layer Well...(read more)

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  • SQL Server v.Next (Denali) : Changes to performance counters

    - by AaronBertrand
    In a previous post about changed system objects in Denali , I talked about the changes to memory-related DMVs due to underlying changes in the memory manager. The SQLOS team has posted a great introduction to these changes , and they plan to post more details in future posts. In the meantime, and due to a question yesterday from Tom LaRock ( blog | twitter ): ...I thought I would tell you about some performance counters that have changed between SQL Server 2008 R2 and Denali - most of which involve...(read more)

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  • Decoding an affinity mask

    - by GavinPayneUK
    Recently, in preparation for my SQLBits NUMA internals session I began looking at some of the SQLOS DMVs and trying to understand how their contents directly related to the physical server architecture that SQL Server was running on. While their contents used regular terms such as node and affinity mask the results were often in an “internals” format that can be distracting to the human reader.  An example of this is the DMV sys.dm_os_nodes (link to Technet here ), or more specifically the column...(read more)

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  • Sampling SQL server batch activity

    - by extended_events
    Recently I was troubleshooting a performance issue on an internal tracking workload and needed to collect some very low level events over a period of 3-4 hours.  During analysis of the data I found that a common pattern I was using was to find a batch with a duration that was longer than average and follow all the events it produced.  This pattern got me thinking that I was discarding a substantial amount of event data that had been collected, and that it would be great to be able to reduce the collection overhead on the server if I could still get all activity from some batches. In the past I’ve used a sampling technique based on the counter predicate to build a baseline of overall activity (see Mikes post here).  This isn’t exactly what I want though as there would certainly be events from a particular batch that wouldn’t pass the predicate.  What I need is a way to identify streams of work and select say one in ten of them to watch, and sql server provides just such a mechanism: session_id.  Session_id is a server assigned integer that is bound to a connection at login and lasts until logout.  So by combining the session_id predicate source and the divides_by_uint64 predicate comparator we can limit collection, and still get all the events in batches for investigation. CREATE EVENT SESSION session_10_percent ON SERVER ADD EVENT sqlserver.sql_statement_starting(     WHERE (package0.divides_by_uint64(sqlserver.session_id,10))), ADD EVENT sqlos.wait_info (        WHERE (package0.divides_by_uint64(sqlserver.session_id,10))), ADD EVENT sqlos.wait_info_external (        WHERE (package0.divides_by_uint64(sqlserver.session_id,10))), ADD EVENT sqlserver.sql_statement_completed(     WHERE (package0.divides_by_uint64(sqlserver.session_id,10))) ADD TARGET ring_buffer WITH (MAX_DISPATCH_LATENCY=30 SECONDS,TRACK_CAUSALITY=ON) GO   There we go; event collection is reduced while still providing enough information to find the root of the problem.  By the way the performance issue turned out to be an IO issue, and the session definition above was more than enough to show long waits on PAGEIOLATCH*.        

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  • Few events I&rsquo;m speaking at in early 2013

    - by Mladen Prajdic
    2013 has started great and the SQL community is already brimming with events. At some of these events you can come say hi. I’ll be glad you do! These are the events with dates and locations that I know I’ll be speaking at so far.   February 16th: SQL Saturday #198 - Vancouver, Canada The session I’ll present in Vancouver is SQL Impossible: Restoring/Undeleting a table Yes, you read the title right. No, it's not about the usual "one table per partition" and "restore full backup then copy the data over" methods. No, there are no 3rd party tools involved. Just you and your SQL Server. Yes, it's crazy. No, it's not for production purposes. And yes, that's why it's so much fun. Prepare to dive into the world of data pages, log records, deletes, truncates and backups and how it all works together to get your table back from the endless void. Want to know more? Come and see! This is an advanced level session where we’ll dive into the internals of data pages, transaction log records and page restores.   March 8th-9th: SQL Saturday #194 - Exeter, UK In Exeter I’ll be presenting twice. On the first day I’ll have a full day precon titled: From SQL Traces to Extended Events - The next big switch This pre-con will give you insight into both of the current tracing technologies in SQL Server. The old SQL Trace which has served us well over the past 10 or so years is on its way out because the overhead and details it produces are no longer enough to deal with today's loads. The new Extended Events are a new lightweight tracing mechanism built directly into the SQLOS thus giving us information SQL Trace just couldn't. They were designed and built with performance in mind and it shows. The new Extended Events are a new lightweight tracing mechanism built directly into the SQLOS thus giving us information SQL Trace just couldn't. They were designed and built with performance in mind and it shows. Mastering Extended Events requires learning at least one new skill: XML querying. The second session I’ll have on Saturday titled: SQL Injection from website to SQL Server SQL Injection is still one of the biggest reasons various websites and applications get hacked. The solution as everyone tells us is simple. Use SQL parameters. But is that enough? In this session we'll look at how would an attacker go about using SQL Injection to gain access to your database, see its schema and data, take over the server, upload files and do various other mischief on your domain. This is a fun session that always brings out a few laughs in the audience because they didn’t realize what can be done.   April 23rd-25th: NTK conference - Bled, Slovenia (Slovenian website only) This is a conference with history. This year marks its 18th year running. It’s a relatively large IT conference that focuses on various Microsoft technologies like .Net, Azure, SQL Server, Exchange, Security, etc… The main session’s language is Slovenian but this is slowly changing so it’s becoming more interesting for foreign attendees. This year it’s happening in the beautiful town of Bled in the Alps. The scenery alone is worth the visit, wouldn’t you agree? And this year there are quite a few well known speakers present! Session title isn’t known yet.       May 2nd-4th: SQL Bits XI – Nottingham, UK SQL Bits is the largest SQL Server conference in Europe. It’s a 3 day conference with top speakers and content all dedicated to SQL Server. The session I’ll present here is an hour long version of the precon I’ll give in Exeter. From SQL Traces to Extended Events - The next big switch The session description is the same as for the Exeter precon but we'll focus more on how the Extended Events work with only a brief overview of old SQL Trace architecture.

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