Kevin Remde's IT Pro Weblog

  • Tracking Hyper-V Dynamic Memory (So Many Questions. So Little Time. Part 6.)

    Justin, in our Saint Louis TechNet Event asked us:

    “How can we track dynamic memory over time? Application vendor's physical requirements are always too high. Resource usage over time can better right-size an app.”

    Speaking of dynamic memory: Remember to download the evaluation softwareAs of SP1 for Windows Server 2008 R2, you have some new Hyper-V performance counters that you can monitor using Performance Monitor that will show you how memory is allocated in Dynamic Memory.

    Here is the section from this document (, Step 4b) in the Windows Server TechCenter on TechNet that explains how to do it:

    The new performance counters are included in two new Hyper-V performance counter groups: Hyper-V Dynamic Memory Balancer and Hyper-V Dynamic Memory VM. You can use the performance counters in these groups to create Data Collector Sets, which you can use to capture and analyze data collected by the performance counters.  For example, you can schedule repeated collection of a Data Collector Set to create logs, load it in Performance Monitor to see the data in real time, and save it as a template to use on other computers.

    To create a Data Collector Set to monitor memory allocation

    1. Start Performance Monitor and add one or more of the new performance counters.
      1. Click Start, right-click Computer, and click Manage. In the Microsoft Management Console navigation tree, click Reliability and Performance.
      2. In the navigation tree, expand Reliability and Performance, expand Monitoring Tools, and click Performance Monitor.
      3. In the menu bar above the Performance Monitor graph display, either click the Add button (+) or right-click anywhere in the graph and click Add counters from the menu. The Add Counters dialog box opens.
      4. In the Available Counters section, scroll through the list to find Hyper-V Dynamic Memory VM and then click the plus (+) sign to expand the group. Select one or more counters from this group, such as Current Pressure and Guest Visible Physical Memory, and then click Add. Click OK to close the dialog box.
    2. Right-click anywhere in the Performance Monitor display pane, point to New, and click Data Collector Set. The Create New Data Collector Set Wizard starts. The Data Collector Set created will contain all of the data collectors selected in the current Performance Monitor view.
    3. Type a name for your Data Collector Set and click Next.
    4. The Root Directory will contain data collected by the Data Collector Set.  Change this setting if you want to store your Data Collector Set data in a different location than the default.  Browse to and select the directory, or type the directory name.
    5. Note: If you enter the directory name manually, you must not enter a back slash at the end of the directory name.
    6. Click Next to define a user for the Data Collector Set to run as, or click Finish to save the current settings and exit.

    For more information about using Data Collector Sets, see “Scenario 3: Create a Data Collector Set from Performance Monitor” in the Performance and Reliability Monitoring Step-by-Step Guide for Windows Server ( ).

  • SCVMM in System Center 2012 and managing Citrix XenServer (So Many Questions. So Little Time. Part 5.)

    This question came from Randy at our TechNet Event in Saint Louis:

    “Are the VMM management capabilities for a Citrix XenServer based VM the same as for a Hyper-V based VM?  (example: can you still live migrate, change RAM, etc?)”

    imageThe simple answer is: The capabilities are pretty much the same.  Live Migration, for example, will simply drive VMs in a managed pool through XenMotion.  There are a couple of considerations in some areas (such as XenServer Templates and networking), but being able to build a Cloud of Citrix XenServer resources right alongside Hyper-V or VMware based clouds is pretty amazing.

    For a full overview on Managing Citrix XenServer using System Center Virtual Machine Manager, CLICK HERE.

    For system requirements, CLICK HERE.

    Note that managing Citrix XenServer in SCVMM requires Citrix’s “Microsoft System Center Integration Pack”, which can be ACQUIRED HERE.

  • Web Server Recommendations (So Many Questions. So Little Time. Part 3.)

    I was asked this question last week at our TechNet Event in Kansas City. 

    “What is Microsoft’s best practice recommendation for web server deployment to support a web site that has variable demands from day-to-day?  Network Load-Balancing?  Private Cloud?  Clustering?.. or something else?”  -Don G.

    Clouds lead to rain which causes the flowers to grow!That’s a very big question, Don. Smile  To answer it of course involves knowing a lot about your application, your customers, the amount of infrastructure that you want to support in-house or are willing to purchase as a hosted solution, etc.  And of course all have to be balanced with your budget and your staff (local expertise).

    If I were building this today and I wanted to host it in-house, I would consider using System Center Virtual Machine Manager 2012 to create the machine templates and the a Service template to represent the application and all of its components.  In this way I could manage the storage, the load balancer (yes, I’d buy a physical one, but I’d want to drive it through SCVMM 2012), and importantly the ability to scale up or scale down the number of instances of virtual machines among the various tiers of my web application. 

    See this blog post for a good description of SCVMM 2012 Service Templates.

    I would also take advantage of the abilities of System Center Operations Manager 2012 for monitoring my application – even to the level of reporting application errors and directing my developers to the offending lines of code.  Using OpsManager will also give me the ability to drive configuration changes when they become necessary, through native integration with SCVMM and through PRO (Performance and Resource Optimization)

    “But what about if you don’t want to host it in-house?”

    Well.. certainly there are a lot of hosters who will let me use their servers or their rack space (ahem).  But honestly, if I want control of my application but don’t want to even have to worry about the datacenter, power, cooling servers, load balancing, network configuration, DNS, security, and massive scalability concerns… and if I want to just pay for what you use and nothing more, then I would consider building my application using Windows Azure.

    * WARNING * - Shameless Blog Self-Promotion: See THIS BLOG POST of mine for a more detailed and most excellent description of Windows Azure.


    Thanks for your question, Don!  And if anyone else would like to comment, or has other answers for Don, please put them in the comments.

  • Breaking News: New System Center 2012 Licensing Model Announced

    Download the pre-release components

    Today during the “Private Cloud Day” live webcast event, Microsoft announced a pretty big change in how we think of and purchase the System Center suite.  Bottom-line.. it’s no longer a separate set of products, but it is just one product: System Center 2012.  (Well.. actually two.. but different only in terms of licensing.) 

    In a nutshell: System Center is now just one product, that comes in two editions, with many components.  And the full-set of components come in the two product editions: 

    System Center Editions and Components

    “So, when I buy System Center, I get the full suite?”

    That’s right.

    “So.. this chart doesn’t show that there is any difference.  What’s different between Standard and Datacenter?”

    Standard Edition is licensed per two physical processors, and each license gives you management rights of two virtualized servers.  Buy as many as you need for the number of virtualized servers you want to manage.

    Datacenter Edition is also licensed per two physical processors, but it provides use rights for management of an unlimited number of VMs per license.

    “What are the benefits to doing this change, Kevin?”

    There are several.  Obviously it’s simple, so that’s a big one.  Licensing by processor, plus giving you the same full set of System Center components for each license, is easy to swallow. 

    Another benefit is that, unlike our biggest competitor in the Virtualization space, we don’t charge you more for additional virtual machines, or charge by number of virtual CPUs or memory used.  One of the biggest reasons to virtualize and move to a Private Cloud  IT-as-a-Service model is in the economics of it.  You want to maximize hardware utilization, drive up density and reduce costs through Virtualization…. so your costs should decrease as your workload density increases, not the other way around.

    “What does this mean for me if I already have some of the System Center products?  Or an enterprise suite?”

    I won’t post all of the details here, but I do know that we’re making it very appealing.  There is a well-thought-out, very fair transition plan that will especially make customers with current Software Assurance (SA) plans very very happy.


    For complete details on the announcement and on System Center 2012, CLICK HERE.

    For the licensing implications and the transition for existing customers, CLICK HERE.

    And please try out the different component Release Candidates HERE.

  • NEW: Microsoft Server Virtualization “Jump Start” training

    Is this guy certified?CHEAP TRAINING!

    “What?  Huh?  Cheap?  Training?”

    Symon Perriman - If you’ve already watched the 8-hour virtualization JumpStart, you’re familiar with Symon Perriman’s easy-going teaching style. A Microsoft Technical Evangelist covering Virtualization, Windows Server, System Center and Private Cloud technologies, Symon is a recognized expert in high availability, failover clustering, network load balancing, storage solutions, mobile, domain and web services. Symon contributed to several technical books for clustering, virtualization and SQL, wrote technology articles for Business Today, and is the founder of Failover Clustering & Network Load Balancing BlogYes, I thought that would get your attention.  Due to the great response for past deliveries of this sort of all-day live virtual classroom training, Symon Perriman and Phil Helsel will be delivering two more full-day courses on Microsoft Virtualization.

    Here are the details (UPDATED - Additional event in February!):

    • What? “Exam 70-659: Windows Server 2008 R2, Server Virtualization Jump Start
    • When? Wednesday, January 11, 2012 from 12pm - 8pm PDT,  Wednesday, February 15, 2012 from 8am - 4pm PDT, or Thursday, February 23, 2012 from 12am-8am PDT (yes, early morning hours).
    • How? Live virtual classroom (online)
    • How much? $99 (includes an exam voucher valued at $150)

    Phil Helsel, MCT, MCITP - A Microsoft Certified Trainer and senior technical instructor with Microsoft FAST University, Philip has a broad range of experience from working at TechNow, Oracle, FAST Search & Transfer, and Sun Microsystems to now teaching IT professional about Windows Virtualization and Enterprise Search. Over the past twenty years, he’s earned a MCT, MCITP: Virtualization Administrator on Windows Server 2008 R2, CTT+, CISM, Security+, Network+, CCNA, and A+.“Wait.. it includes an exam voucher?  So I can pay $99, take this class, and then I have a voucher to take the certification exam?”

    That’s right.  We’ll give you a voucher to use, and you will want to take the TS: Windows Server 2008 R2, Server Virtualization certification exam to take full advantage of what you’ve learned and become a “Microsoft Certified Technology Specialist (MCTS): Windows Server 2008 R2, Server Virtualization”.

    See the Microsoft Certified Community Connection page for complete details.


    And don’t forget that if you want to get a leg-up on this stuff, you can freely download and evaluate Windows Server 2008 R2 w/SP1 and SCVMM 2008 R2 SP1, and build a pretty solid training environment on one or two PCs.

  • Breaking News: Free Private Cloud “Jump Start” Training

    Microsoft has just scheduled a FREE 2-day training course entitled “Creating and Managing a Private Cloud with System Center 2012 Jump Start”, happening on February 21st-22nd, 2012 from 9:00am to 5:00pm PST

    Jump Start Training

    Adopting this exciting new computing paradigm provides a whole new landscape of technology and career direction for IT professionals. Microsoft Learning and the Microsoft System Center 2012 team have partnered to bring you an exciting opportunity to learn what you need to know to deploy, manage and maintain Microsoft’s private cloud solution. Leveraging the popular Jump Start virtual classroom approach, the industry’s most gifted cloud experts will show attendees why this new private cloud solution, based on System Center 2012 and Windows Server, has garnered so much attention. Here are the details:

    • Course: “Creating and Managing a Private Cloud with System Center 2012 Jump Start”
    • Date/Time: February 21-22, 2012 from 9:00am – 5:00pm PST
    • Where: Live virtual classroom (online from wherever you are)
    • Cost: FREE!
    • Target audience: IT Professionals (IT Implementers, managers, decision makers)

    “What’s a ‘Jump Start’ course?”

    From the registration page:

    “Training specifically designed for experienced technologists whose jobs demand they know how to best leverage new, emerging Microsoft technologies. These advanced courses assume a certain level of expertise and domain knowledge, so they move quickly and cover topics in a fashion that enables teams to effectively map new skills to real-world situations.”

    “And.. did you say ‘FREE’?”

    Yes, I did. 

    “Is there anything I can do to get ready for this?

    Download and install the System Center 2012 evaluation software:

    Then go to this page for course details, schedule, speakers, registration link, and fabulous prizes.

    “Huh?  Prizes?”

    Not really.  I was just seeing if you were still paying attention.

  • Migrating from Microsoft Virtual Server to Hyper-V (So Many Questions. So Little Time. Part 7.)

    At our TechNet Event in Saint Louis, Matt J asked:

    “How do I migrate from Microsoft Virtual Server to Hyper-V?”

    Want to try out Hyper-V?  Get the free Windows Server 2008 R2 evaluation.I haven’t been asked that for quite awhile (about 3 years, actually).  But we did have a few people at our event in Saint Louis that are still using Microsoft’s previous virtualization solution, Virtual Server.  Thankfully, because Hyper-V uses the same .VHD format for virtual hard disk files as did Virtual Server, the process is actually pretty straightforward.  From this document:

    Migrating your virtual machines that are running on Virtual Server 2005 R2 SP1 to Hyper-V is a straightforward process. To migrate, you do the following general steps:

    1. Prepare the virtual hard disk in Virtual Server.
    2. Move the .vhd file (if necessary).
    3. Create a new virtual machine in Hyper-V using the .vhd file.

    THIS PAGE spells it all out for you.

  • Private Cloud Day–A Big Deal and a Big Event

    This Tuesday, January 17, 2012, Microsoft is holding a special Private Cloud webcast

    Transforming IT with Microsoft Private Cloud

    “Special?  What’s so special?”

    Transforming IT with Microsoft Private CloudI’ll tell you why.  Well, actually I can’t tell you all the details (because I don’t know them), but what I can tell you is that you’ll learn a lot.  The webcast features Satya Nadella – President, Server and Tools Business, Brad Anderson – Corporate Vice President, Management and Security Division, Jacky Wright - Vice President, IT Strategic Services, Microsoft IT, and Rand Morimoto, Chief Executive Officer, Convergent Computing. 

    “Wow.. those are some pretty important folks.”

    Exactly.  And they don’t just show up on a webcast unless there are some pretty important reasons.

    Here is the description of the event from the event registration page:

    The definition and the virtue of “the cloud” have been hotly debated in recent months. Many agree that both the public and private cloud can accelerate innovation, reduce costs, and increase business agility in the market. While there are lofty expectations over the next few years for this technology, many professionals in IT are already reaping the benefits of cloud computing to drive their organizational goals.

    Join us for an interactive virtual event featuring both Microsoft executives and fellow CIOs:

    • Be among the first to hear the latest private cloud news from Microsoft
    • Learn from other senior professionals in IT about how cloud computing is helping drive greater results
    • Evaluate Microsoft’s cloud offerings, including a deep dive into the private, public and hybrid cloud models
    • Learn how to leverage the cloud to gain maximum competitive advantage at minimal risk
    • Experience a scenario-based demonstration of Microsoft's private cloud computing solutions

    “C’mon, Kevin.. Is this webcast really that important?”

    For understanding the future of Microsoft’s Private Cloud platform solutions, yes, it is.  It is so important, in fact, that during our TechNet Event in Saint Louis that day we’re going to carve out some time to watch the broadcast together.  Pretty important.

    CLICK HERE for more information.  See you there.

  • What’s new in Windows Server “8” Virtualization? (So many questions. So little time. Part 2.)

    Here are another set of really good questions from our TechNet Event on Tuesday in Kansas City.  These came all on the same slip of paper, from the same person.


    “How will Windows 8 / Server 8 change Microsoft Virtualization?”

    a new foundation for the private cloudIn Windows Server “8” there are a great many improvements in Hyper-V; many more than can (or need to) be adequately restated in here in my blog.  So to answer you question I will point you to some good resources on virtualization improvements in Windows Server “8”.  HERE is a great blog post from the Microsoft Server and Cloud Platform Blog that introduces all of the most important Server “8” Hyper-V improvements.

    In Windows “8” client, the biggest news (in my opinion) is that we will be including Hyper-V as a built-in option.  I’ll say it again.. on Windows “8” CLIENT (the desktop/notebook/tablet operating system) we will be including Hyper-V as an installable option.  That’s HUGE.

    Read Stephen Sinofsky’s blog post about it, HERE.


    “Will the Hyper-V synthetic network adapter ever be capable of supporting PXE boot?”

    I haven’t been able to find a definitive answer on this question (and if you have it, please add it in the comments), but I rather suspect the answer is no; and here’s why…

    Currently the synthetic network adapter, optimized for efficient data throughput through the VMBus, is a benefit of the Integration Components that are running within the virtual machine.  And since it is a part of this “enlightenment” that is running within the VM, it is something that is NOT running prior to the operating system actually loading. 

    Perhaps we will improve or replace or give another option to using the slower “legacy adapter” – the one that does allow PXE boot.  But I don’t have that answer.  Yet.


    “What are the requirements and limitations of RemoteFX for VDI?”

    VDI with Cloud - From Don MacVittie - Persistently DifferentFirst of all, if you’re not familiar with what RemoteFX is, I encourage you to READ THIS article on the Microsoft Virtualization blog..

    Second, as a solid overview of what’s new and exciting in Windows Server “8” for VDI and RemoteFX, I must borrow some text from a very well-done article by Jason Perlow:

    “VDI… Did I mention the VDI improvements? Windows Server 8’s Remote Desktop Session Host, or RDSH (what used to be called Terminal Server) now fully supports RemoteFX and is enabled by default out of the box.

    What’s the upside to this? Well now you can put GPU cards in your VDI server so that your remote clients, be it terminals or tablets or Windows desktops that have the new RemoteFX-enabled RDP client software can run multi-media rich applications remotely with virtually no performance degradation.

    As in, completely smooth video playback on remote desktops, as well as the ability to experience full-blown hardware-accelerated Windows 7 Aero and Windows 8 Metro UIs with full DirectX10 and OpenGL 1.1 support on virtualized desktops.

    This will work with full remote desktop UIs as well as ‘Published’ applications, a la Citrix. And no, you won’t need Citrix XenApp in order to support load balanced remote desktop sessions anymore. It’s all built-in.

    RemoteFX and the new RDSH is killer, but you know what’s really significant? You can template virtual desktops from a single gold master image stored on disk and instantiated in memory as a single VM and then customize individual sessions to have roaming profiles with customized desktops and apps and personal storage using system policy. That conserves a heck of a lot of disk space and memory on the VDI server.

    And in Server 8, RDP is also now much more WAN optimized than in previous incarnations.”

    Please read Jason’s full article “Windows Server 8: The Ultimate Cloud OS?” for a very good introductory overview of what’s new in Windows Server “8”.

    And finally - Your question was much more specific than that.  What are the requirements and limitations? 

    Beyond some good news about relaxed requirements for graphics processor requirements on servers, virtualizing some of that processing, and even the great news for better support in remote desktops mentioned above, I don’t know of any technical specs yet available.  I expect more will be released on-or-around the beta release timeframe.


    For those of you interested in getting the current, full story on Windows Server “8”, please read this post, and watch the Windows Server 8 blog

    And if you have more questions or requests or better answers or off-the-wall-remarks, please give me a comment or two!

  • Impact on PRO when upgrading SCOM and SCVMM to System Center 2012 (So many Questions. So Little Time. Part 4.)

    This question was asked by Aubrey M at our Kansas City TechNet Event last week…

    Happily evaluating the newest software tools“If you have PRO enabled between SCOM 2007 R2 and SCVMM, how will that affect the upgrade process for these two systems?”

    (For those of you who haven’t heard of PRO, check out this resource.)

    The short answer is that upgrading SCVMM to the new 2012 version will remove the connection/integration between OpsManager and VMM.  Here are the bullet-points from the “Planning Considerations for Upgrading to VMM” page:

    • Performance and Resource Optimization (PRO) configurations are not maintained during an upgrade to System Center 2012 – Virtual Machine Manager.
    • If you have an existing connection to Operations Manager, the connection is removed during the upgrade process.
    • If you do not want the connection to be removed automatically, remove the connection manually before upgrading.
    • After the upgrade process completes, you can reconfigure your connection to Operations Manager.
    • For information about using Operations Manager with System Center 2012 – Virtual Machine Manager, see Configuring Operations Manager Integration with VMM.

    Yours is an excellent question, and one that is related to (and begs the answer to) the bigger question: Will I be able to do an in-place upgrade?  And the answer to that question is different depending upon which System Center product you are moving to 2012.  So here is a quick-and-dirty list of the new System Center 2012 products, whether or not they support an in-place upgrade, and where to go for more information.  (Note: this list only assumes that you have the most recent version of the current application, and are running them on Windows Server 2008 R2 with SP1.  See the “additional information” links for complete requirements, considerations, and guidance.)

    System Center Virtual Machine Manager 2012 
    In-place upgrade supported: Yes
    Additional Information HERE.

    System Center Configuration Manager 2012 
    In-place upgrade supported: No.  It’s a migration.
    Additional Information HERE

    System Center Operations Manager 2012 In-place upgrade supported: Yes
    Additional Information HERE

    System Center Service Manager 2012  
    In-place upgrade supported: Yes
    Additional Information HERE (beta)

    System Center Orchestrator 2012 (from Opalis)
    In-place upgrade supported: No.  It’s a migration.
    Additional Information HERE

    System Center Data Protection Manager 2012
    In-place upgrade supported: ?? – DPM 2012 is still in beta, and I haven’t been able to find any current information on upgrade support. (If you know the answer, please post it in the comments.)
  • BREAKING NEWS: TechNet Subscription Discount!

    Those of you who also get the TechNet Flash e-mails already know this… We’ve announced a 15% discount offer for new TechNet Professional Subscriptions.

    From now until February 29th, 2012 Microsoft TechNet Flash subscribers will receive a 15% discount on a new Microsoft® TechNet Subscriptions Professional”


    The discount code to use to get 15% off is TNFLA12

    The terms and conditions say it’s just for TechNet Flash subscribers.  So before you buy your new TechNet Professional Subscription with this discount code, and if you haven’t already, make sure you subscribe to the TechNet Flash newsletter

  • How much can virtualization really do? (So many questions. So little time. Part 8.)

    In our Saint Louis TechNet Event last week, Kurt asked several questions relating to virtualization and Hyper-V:

    Powered by Hyper-V“Any issues with running SBS, SQL, and application server on same machine?”

    “How do I set up multiple drives within a virtual server?”

    “What is the best base core for virtualization? (Enterprise, File Server, etc.)”

    To your first question, Kurt, there is really no one correct answer.  “It depends.”, is really qutie appropriate, here.  If you have a pretty decent server with lots of memory and processors / cores, and you’re not supporting a huge enterprise (your mention of SBS makes me believe that there are no more than 75 users, so you’re fine there), you can do this.  And in fact when you use Small Business Server, that is essentially what you are doing. 

    Your second question is more specific to Hyper-V.  To add additional drives to a virtualized server in Hyper-V, you simply edit the settings of the virtual machine.  You can create the new .VHD files before (using the New –> Hard disk.. utility in the Hyper-V management console), or during the addition of the disk to the machine.  Note that you can also add or remove disks to/from a live, running machine; provided that the disk is being added to a virtual iSCSI adapter and not one of the IDE adapters.

    Once a disk is added, you will have to go into the Storage Management (in Server Manager) within the virtual machine.  If the disk is brand new and previously un-partitioned or unformatted, you will do that from the Storage Management tool.

    For details on configuring virtual machines, CLICK HERE

    Finally, you are asking for “the best base core” for virtualization.  Forgive me if I didn’t interpret your handwriting correctly, but I believe what you’re asking is, “What is the best use of virtualization?”  And again, a lot of this answer is going to depend upon your environment and the applications and services (and servers) you are supporting.  Most companies try it out on a small-scale in production; perhaps virtualizing file servers or print servers, and move gradually to more complex or business-critical servers.  Eventually, when they are convinced that they can safely do it, and can support the infrastructure (including management and monitoring) to efficiently support it, they move the bulk of their operations to virtualized machines.  Go to for a good starting point on researching what Microsoft has to offer.  And visit to search for examples of companies who are making good use of the solutions you’re investigating.

    And as always, you can start out by evaluating Windows Server 2008 R2 w/SP1 for free, to start learning about and working with Hyper-V.

  • In case you missed it: The Private Cloud Webcast

    YTry it out!esterday the big news from Microsoft was the announcement of and new details around the new System Center 2012 product, delivered via live Webcast.  I was very happy to be able to watch the webcast with John Weston and 88 of our closest friends in Saint Louis during our TechNet Event.

    “I wasn’t able to see the webcast.  What did I miss?”

    You’re in luck!  I summarized the webcast here.  But even better, you can watch the recording in its entirety.

    CLICK HERE to view the recording.

    And don’t forget to GET THE CURRENT BITS HERE.

  • So Many Questions. So Little Time (part 1)

    Frozen NorthIt’s another snowy day up here in Minneapolis, but earlier this week I had the pleasure of traveling down to tropical Kansas City.  Overland Park, KS, to be more specific.  And on that particular day we decided to try something new.  We (John Weston and I) asked our attendees to write down questions, topic areas, off-hand remarks, and comments on slips of paper during the event.  What we wanted to do was help facilitate some more discussion during our IT Camp.

    “IT Camp?  What’s that?”

    An IT Camp is like a TechNet Event without (or with minimal) PowerPoint.  It’s more of a discussion than a presentation.  It’s interactive, loose, and fun.  We have some topics to discuss and certainly some information to disseminate, but we want the conversation to be driven mainly by the audience. 

    Anyway.. the reward for good questions was a T-Shirt.  And the result of this ask of our guests was phenomenal.  I have sitting here on my desk a pretty nice stack of questions; most of which we were able to answer during the event, but some we didn’t have time to get to. 

    So what I want to do is to put the questions up here on my blog (the ones I can read, anyway.. some of you folks should have been Doctors, because I can’t read your writing!), and then I’ll summarize the answer that we gave, or make up (?!) a new one for you here. 

    Disclaimer: I will provide links to additional information and the sources of my answers, but some of my answers will be opinions and speculation.  This is a blog – not a knowledgebase article.  You have been warned.


    Here we go with question #1…

    “Given that differencing disks enable multiple instances of a running OS from a single OS image, please discuss and outline an appropriate best practice patch management strategy.”   -David U.

    Parent-Child LinkFirst of all, for those of you who may not be familiar with the concept of a differencing disk… Differencing disks are virtual hard disk (.VHD) files that link from child, to parent, to grandparent.  The idea is that you can create an install of an OS as a virtual machine.. and then use that .VHD hard disk installed OS to be the basis for one or more child disks.  The children start from that point, and their parent disk is never ever modified.  (It can’t be, because doing so would break the children.)  You can do this process of linking down many levels if you choose.  Even though some content of the parent disks are being read as a part of the disks that are in use or running operating systems, all changes are happening in the children at the end of the hierarchy. 

    For a more complete description of differencing disks, CLICK HERE.

    To answer your question, I first need to go back to what I said: the parent disk is never ever modified.  This implies that all patching and updates can only happen on the last child in the chain, so updates will always be applied there.

    So.. a big benefit of differencing disks is in having a common, pre-installed operating system starting point for many running machines that can be created quickly.  And the amount of disk space saved initially is enormous, because many machines are sharing a common set of bits for their running installations, while the differencing disk starts out very small and only grows when there are changes.

    But the downside (besides a slight degradation of performance) is that, eventually, through the natural changes and updates that occur, the differencing (child) disks will be as big or bigger than the parent disk it’s linked to.

    So how does one approach patch management?  

    You need to (for now, at least) get beyond the desire to patch the parent disk.  It’s not possible.  It may be someday**, but not at this time.  So with that in mind, your best practices around patch management really can’t consider the fact that these machines are running off of a common parent disk; other than the fact that eventually you might want to create a new starting-point, fully patched OS disk to build new children from. 

    **I say this only because it seems like a good idea to add as a feature in the future. I have no knowledge whatsoever on whether this is being planned or created.

    My recommendations:

    In a lab environment, it’s a great tool for quickly rolling out new machines.  Eventually (maybe before every major re-build or re-think or new project) you may want to create a new machine off of the old parent, apply updates, shut ‘er down, and then consolidate the changes into one new parent disk.  (for instructions on how to merge a child differencing disk with its parent, CLICK HERE

    For production use, however, the limitations long-term out-weigh the benefits.  For the sake of performance and simplicity, and even for reducing storage requirements longer-term, I suggest that you don’t use differencing disks for production workloads.  Treat your production virtual machines as you would any other physical machine; which includes your patch management practices.