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  • Django 1.5 custom User model error. "Manager isn't available; User has been swapped"

    - by bpetit
    I extend the django user model as described in the dev doc. I wan't to keep most of the original User model features so I extend the AbstractUser class. I've defined in settings.py: AUTH_USER_MODEL = 'myapp.CustomUser' My user class: class CustomUser(AbstractUser): custom_field = models.ForeignKey('OtherModel') objects = UserManager() Everything seems to work fine but when I try to make it managed by the admin site: admin.site.register(CustomUser, UserAdmin) I get this error on the admin CustomUser creation page (after validation of the password confirmation form): AttributeError: Manager isn't available; User has been swapped for 'myapp.CustomUser' The point is that I need this model managed by the admin site in order to have the same creation process as with the original User model (two step process with password validation). Thanks for any reply

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  • SQLite3 or SQLite Manager make me crazy !!! Please help me !! I have a presentation next week

    - by ahmet732
    My friend added 90 rows into the database, I tied it up to my app. In my table view name of my variables are shown in proper fashion but when I tapped one of them, in detailsViewController their description is wrong. It shows very old description of variables not the new ones in database. Moreover, it displays the same description for different variables. What's the problem ? What am i missing? My database is correct. It displays same desscriptions for different values. It makes me worried about. Additionally, when I added a new row to my db, it accepts it but it does not perceive it when i run the app. It shows new row in my tableview if and only if I change the name of my db file. I do not want to use another SQL manager ..

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  • Hiring a project or development manager: what are good interview questions?

    - by Totophil
    What questions would you ask a candidate applying for a software project or development manager position? Please could you submit one question per answer (with multiple answer if necessary) or a sequence of related questions. This way eventually all questions will get ordered by how good we all think they are. Please also provide a short guidance for evaluating possible answers. UPDATE: It seems that a large proportion of the answers so far are aimed at generic management skills. What would you ask someone who is going to manage software development, let's say in your organisation? What knowledge, skills and attitude will you be looking for in the candidate replies?

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  • Need help optimizing a NHibernate criteria query that uses Restrictions.In(..)

    - by Chris F
    I'm trying to figure out if there's a way I can do the following strictly using Criteria and DetachedCriteria via a subquery or some other way that is more optimal. NameGuidDto is nothing more than a lightweight object that has string and Guid properties. public IList<NameGuidDto> GetByManager(Employee manager) { // First, grab all of the Customers where the employee is a backup manager. // Access customers that are primarily managed via manager.ManagedCustomers. // I need this list to pass to Restrictions.In(..) below, but can I do it better? Guid[] customerIds = new Guid[manager.BackedCustomers.Count]; int count = 0; foreach (Customer customer in manager.BackedCustomers) { customerIds[count++] = customer.Id; } ICriteria criteria = Session.CreateCriteria(typeof(Customer)) .Add(Restrictions.Disjunction() .Add(Restrictions.Eq("Manager", manager)) .Add(Restrictions.In("Id", customerIds))) .SetProjection(Projections.ProjectionList() .Add(Projections.Property("Name"), "Name") .Add(Projections.Property("Id"), "Guid")) // Transform results to NameGuidDto criteria.SetResultTransformer(Transformers.AliasToBean(typeof(NameGuidDto))); return criteria.List<NameGuidDto>(); }

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  • Overwrite queryset which builds filter sidebar

    - by cw
    Hi, I'm writing a hockey database/manager. So I have the following models: class Team(models.Model): name = models.CharField(max_length=60) class Game(models.Model): home_team = models.ForeignKey(Team,related_name='home_team') away_team = models.ForeignKey(Team,related_name='away_team') class SeasonStats(models.Model): team = models.ForeignKey(Team) Ok, so my problem is the following. There are a lot of teams, but Stats are just managed for my Club. So if I use "list_display" in the admin backend, I'd like to modify/overwrite the queryset which builds the sidebar for filtering, to just display our home teams as a filter option. Is this somehow possible in Django? I already made a custom form like this class SeasonPlayerStatsAdminForm(forms.ModelForm): team = forms.ModelChoiceField(Team.objects.filter(club__home=True)) So now just the filtering is missing. Any ideas?

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  • why don't more programming languages have builtin interfaces to the window manager?

    - by Naveen
    Programming is at the heart about automating tasks on a computer. Presumably those tasks would normally be done manually by a human. Humans use the computer through the keyboard, mouse, and interaction with the console or the window manager. But very few languages have built in functions that provide an interface to these basic computing objects. A notable exception is autohotkey, an open source language on windows, providing builtin functions that allow the following simple tasks: * Get Pixel Information * Get mouse position * Keyboard macros * Simulate key strokes * Simulate mouse click * Window management See examples on rosettacode. There have been various attempts on linux, many of which were stopped without explanation. One is the inactive tcl library: android. Search google code for android, lang:tcl

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  • What are the key steps a Developer needs to go through to become a good Project Manager?

    - by adpd
    I am a full-time Developer who aspires to be a great technical Project Manager. What are the key steps that you think I need to go through to achieve that aspiration? I am interested in professional qualifications (e.g. PRINCE2, etc.), training courses, personality traits, experiences, tips and techniques that would improve my chances of being the best I can be. I would be interested in hearing if anybody has done this, and whether they are happy with their change from development or if they wished they had stuck to a development (and the reasons behind this decision).

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  • (Windows) How to lock all applications (explorer, task manager etc.) and make only the browser activ

    - by Unni
    I'm trying to run only the browser in the system - locking access to everything else. Only the supervisor can resume the normal functioning of the system after giving a password. This kind of activity is usually done by virus. Disabling the registry for Task manager etc. Does anyone know of any source available that does this? I might be able to pull it off in Windows XP. But have anyone tried this in Windows 7 ? The aim is to to emulate the Chrome OS on Windows. Only the browser. Nothing else.

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  • Prioritizing Product Features

    - by Robert May
    A very common task in Agile Environments is prioritization.  Teams that are functioning well will prioritize new features, old features, the backlog, and any other source of stories for the team, and they’ll do it regularly. Not all teams are good at prioritizing according to the real return on investment that building stories will yield to the company.  This is unfortunate.  Too often, teams end up building features that are less valuable, and everyone seems to know it except perhaps the product owner!  Most features built into software are never even used.  Clearly, not much return for features that go unused. So how does a company avoid building features that add little value to the company?  This is a tough question to answer, but usually, this prioritization starts at the top with the executives of the company.  After all, they’re responsible for the overall vision of the company. Here’s what I recommend: Know your market. Know your customers and users. Know where you’re going and what you want to achieve. Implement the Vision Know Your Market We often see companies that don’t know their market.  Personally, I’m surprised by this.  These companies don’t know who their competitors are, don’t know what features make their product desirable in the market, and in many cases, get by with saying, “I’ve been doing this for XX years.  I know what the market wants!”  In many cases, they equate “marketing” with “advertising” and don’t understand the difference. This is almost never true.  Good companies will spend significant amounts of time and money finding out who they’re competing against and what makes their competitors successful in the marketplace.  Good companies understand that marketing involves more than just advertising.  Often, marketing is mostly research and analysis, not sales.  Until you understand your market, you cannot know what features will give you the best return on your investment dollar. Good companies have a marketing department and can answer the next important step which is to know your customers and your users. Know your Customers and Users First, note that I included both customers and users.  They’re often not the same thing.  Users use the product that you build.  Customers buy the product that you build.  It’s a subtle difference, but too often, I’ve seen companies that focus exclusively on one or the other and are not successful simply because they ignore an important part of the group. If your company is doing appropriate marketing, you know that these are two different aspects of your product and that both deserve attention to have a product that is successful in your target market.  Your marketing department should be spending a lot of time understanding these personas and then conveying that information to the company. I’m always surprised when development teams think that they can build a product that people want to use without understanding the users of that product.  Developers think differently than most people in the world.  They know what the computer is doing.  The computer isn’t magic to them.  So when they assume that they know how to build something, they bring with them quite a bit of baggage.  Never assume that you know your customer unless you’re regularly having interaction with them.  Also, don’t just leave this to Marketing or Product Management.  Take them time to get your developers out with the customers as well.  Developers are very smart people, and often, seeing how someone uses their software inspires them to make a much better product. Very often, because the users and customers aren’t know, teams will spend a significant amount of time building apps that are super flexible and configurable so that any possible combination of feature can be used.  This demonstrates a clear lack of understanding of the customer.  Most configuration questions can quickly be answered by talking to the customer.  In most cases, if your software requires significant setup and configuration before its usable, you probably don’t know your customers and users very well. Until you know your customers, you cannot know what features will be most valuable to your customers and you cannot build those features in a way that your customers can use. Know Where You’re Going and What You Want to Achieve Many companies suffer from not having a plan.  Executives will tell the team to make them a plan.  The team, not knowing their market and customers and users, will come up with a plan that doesn’t reflect reality and doesn’t consider ROI.  Management then wonders why the product is doing poorly in the market place. Instead of leaving this up to the teams, as executives, work with Marketing to understand what broad categories of features will sell the most product in the marketplace.  Then, once you’ve determined that, give this vision to the team and let them run with it.  Revise the vision as needed, but avoid changing streams frequently.  Sure, sometimes you need to, but often, executives will change priorities many times a month, leading to nothing more than confusion.  If the team has a vision, they’ll be able to execute that vision far better than they could otherwise. By knowing what products are most important, you can set budgetary goals and guidelines that will help you achieve the vision that was created. Implement the Vision Creating the vision is often where the general executives stop participating in the plan.  The team is responsible for implementing that vision.  Executives should attend showcases and and should remain aware of the progress that the team is making towards meeting the vision, however. Once a broad vision has been created, the team should break that vision down into minimal market features (MMF).  These MMFs should be sized using story points so that, using the team’s velocity, an estimated cost can be determined for each feature.  The product management team should then try to quantify the relative value of the MMFs based on customer feedback and interviews.  Once the value and cost of creating the feature is understood, a return on investment can be calculated.  The features should then be prioritized with the MMF’s that have the highest value and lowest cost rising to the top of features to implement.  Don’t let politics get in the way! Once the MMF’s have been prioritized, they should go through release planning to schedule them for implementation. Conclusion By having a good grasp on the strategy of the company, your Agile teams can be much more effective.  Each and every story the team is implementing will roll up into features that matter to the company and provide ROI to them.  The steps outlined in this post should be repeated on a regular basis.  I recommend reviewing them at least once per quarter to make sure that the vision hasn’t shifted and that the teams are still working on what matters most to the company. Technorati Tags: Agile,Product Owner,ROI

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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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  • Dell Management Packs in System Center Operations Manager 2007 R2?

    - by bwerks
    Hey all, I recently set up SCOM in a small business network environment. The root management server is a Dell Poweredge 2950, and I'd like to use SCOM to monitor it using Dell's management packs. I've imported the management packs into the SCOM deployment and followed Dell's installation instructions, but it doesn't seem to be fully working yet. Currently, the Diagram views in the Dell tree (Monitoring tab) seem to show me the server's place in the network topology, so it seems that at least part of it is working. However, none of the reports under "Performance and Power Monitoring Views" provide any information. When clicking on one of them (Power Consumption (Watts), for instance), the display area is blank and there is a tooltip visible that reads "No performance counter is selected. To select a counter, place a check mark in the Show column in legend below." However, in the legend, there's nothing there for me to check. I've installed OpenManage 6.2 on the server as per the Dell documentation, but I don't know what else I could have done that I missed. Does this sound like a familiar problem to anyone?

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  • Is there an effective tab manager for Google Chrome?

    - by Mahn
    I've tried a few extensions but I wasn't very satisfied, I'm basically looking for an extension that allows me to group sets of tabs in such a way that I'm able to quickly switch between the groups within the same window. That is to say, if I had 5 Wikipedia tabs and 5 Stack Exchange tabs, ideally I would create 2 groups, hide the tabs of one of them, and switch between the Wikipedia and Stack Exchange tabs back and forth as I need without leaving the same window (note that I'm not specifically looking for grouping by site, that was just a simplified example) Does an extension like this exist? PS: No, I don't actually have 5 Wikipedia tabs open while browsing Stack Exchange sites :-)

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  • What are the side-effects of disabling the old Lan Manager hash?

    - by Bigbio2002
    All of the computers in our domain are running Windows XP/Server 2003 and above (with one exception, a Win2Ksp4 server, which is not a domain controller). I intend to disable the LM hashes via group policy as indicated in KB299656, and want to ensure that there won't be any unforseen problems or side-effects. Does anyone have experience with performing this change? Are there any caveats that I should keep in mind?

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  • How should one manager external and internal DNS servers at the same time?

    - by erotsppa
    We run a mac network here in the office. We have an internal DNS server to manage the network. Everything is resolved to a local ip (for mail.mydomain.com etc). However, we also have an external DNS server for when our users are not in the office. However, isn't it a pain to have to manage two lists? Whenever you change something you have to change another? And you can't have one be a slave of another because the ip are sometimes different (for example mail.mydomain.com would point to a local ip in local dns server but an external ip in the external dns server). Any tricks?

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  • What exactly is the difference between update-manager -d and normal apt-get?

    - by jldugger
    The official recommendation of Ubuntu is to use sudo do-release-upgrade to do an online upgrade from one version to the next. Historically many of my Debianite friends and myself have simply altered apt's sources.list and run apt-get dist-upgrade. I follow Ubuntu's recommendations, but I've always wondered what the magic difference between these two processes is. What, exactly, does do-release-upgrade do, on say an upgrade from 9.04 to 9.10? (Examples from other releases welcome.)

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  • Ditto (clipboard manager): can't set shortcut of Win+<num>. Get “Error Registering Position 1”

    - by Jeff Kang
    Somone made a Youtube video on Ditto, and that person uses Win+Num to paste items from the list. He put a screenshot of his settings on Google Plus: When I try to do the same, which is to put “1” in the text field of Position 1, and check the “Win” box to add the Windows key as the sole modifier for the shortcut, which will be Win + 1, I get an error in that says “Error Registering Position 1” in a window titled CP_Main: Could it be because Win+Num conflicts with the natural Win+Num shortcut (starts the application pinned to the taskbar in that position, or switches to that program) of Windows 7? Thanks.

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  • Formatting not retained in paste from Ditto (clipboard manager). Plain text pasted instead [Solved] Add supported types

    - by Jeff Kang
    I'm trying to use Ditto on the Ditto documentation. If I were to copy the table of contents, then paste it (without Ditto) to the word processor, I get http://i.imgur.com/V1GU3.png, and the formatting is maintained. As as a result of the copy operation, the table of contents also goes into the Saved Items List (= History List = Lists the Clips saved from the Clipboard) in Ditto’s Main Window: I open a blank document to paste from Ditto instead of the default clipboard, and press either Ctrl-`, the default Ditto window activation Global Hot Key, or click the tray icon. From this point, I can do 3 things to close the Ditto window, and place the item on the clipboard (the default clipboard?). Select the item, and press Enter Put the cursor on the item, and double-click Select the item, and press Ctrl-c 1) and 2) send a right-click where the cursor is, after the Ditto window closes (presumably to have the paste option ready to access?): Ctrl-c just closes the Ditto window. Whichever method is used, the contents are pasted in what I believe is plain text: http://i.imgur.com/mQAZH.png How do I keep the formatting that the default clipboard keeps? Thanks.

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  • Is there an simple but good To Do Manager app for the Mac?

    - by Another Registered User
    Every morning I think about what I am going to do today. So I take a paper and start to write things like: [ ] Call Mr. XYZ [ ] Answer Support E-Mails [ ] Reduce website header height by 20 px [ ] Create new navigation bar icons And every time I'm done with something, I paint a checkmark in this square. On paper. It would be fun to have something like this as an application. But I don't want a heavy project management tool or integration with email. It should be like download, install, use without fat configuration and steep learning curve. usually I don't schedule my to do's, I just write down every day what I want to accomplish today. For my experience it doesn't make sense to plan what to do next week, because next week everything looks totally different. Would be cool if such a simple utility exists. At the moment I try just using textEdit and deleting rows which are done. With a nice interface, this would be much more fun.

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