Posts Tagged ‘Virtualisation’

HP Sizing and Configuration Tool for Microsoft Hyper-V

Monday, November 23rd, 2009

The HP Sizing and Configuration Tool for Microsoft Hyper-V is a downloadable, automated tool that provides a quick and consistent methodology to determine a “best-fit” server configuration for your virtualized Hyper-V environment. This tool enables you to quickly compare different solution configurations and obtain a highly detailed, customizable server and storage solution complete with a detailed bill of materials.

This sizer allows users to create new Hyper-V solutions, open already saved solutions, and use data compiled from other tools like Microsoft’s Assessment and Planning (MAP) toolkit to build rich Hyper-V configurations built on HP ProLiant server and storage technologies.

The sizer allows rapid comparisons of various Hyper-V characterizations and server platform choices. You can select and customize configurations for your particular environment by adding or substituting server types, number of servers, and server components.

The sizer was developed from knowledge gained during performance characterization testing of Microsoft Hyper-V in the HP Solutions Engineering lab in Houston, Texas

HP Sizing and Configuration Tool for Microsoft Hyper-V

Should I virtualise my Domain Controllers ?

Thursday, November 12th, 2009

Now that’s a difficult question. If you asked me “Can I virtualise my Domain Controllers” then that’s a different question to which the answer is “Of course, its fully supported depending on your virtualisation platform and the version of Windows being used but if you’re on the latest Hyper-V and the latest Windows then its fine”. The question “Should I virtualise my Domain Controllers ?” recognises that you can but that you have a choice as to whether you do or not and, as with any IT decision, you should research, size and plan. What I’d like to talk about today is two items to consider when thinking of virtualising domain controllers.

The first is around synchronisation of system clocks. As mentioned in a previous article windows Servers use time synchronisation to ensure against replay attacks and thus increase the security of Kerberos authentication within an Active Directory environment. However, virtual platforms such as VMWare or Hyper-V also allow you to synchronise a virtual machines clock with the physical host. What this means though is that, if the server host is showing a different time from the root PDC Emulator then any virtualised domain member server or domain controller will set its clock against the domain and then set its clock against the physical host and then against the domain and then against the physical host and so on ad nauseum. This can cause five issues:

  1. If there is more than the amount of “difference” between the DC clock and other domain controller clocks then the server will not be able to synchronise
  2. Similarly, as the DC clock will different from those of clients, clients will fail authentication against this domain controller.
  3. This constant re-synchronisation will cause clock “flapping” so that any events or logs written will have events recorded in an incorrect order. This is an issue not only for domain controllers but also for other servers such as SQL or Exchange where they record the time of records being changed or messages arriving.
  4. If you run an environment where accurate times are important then this will into be possible with “flapping” clocks. For example, if you require staff to “clock in” and penalise them for late arrival then your solution will be at risk if your clock cannot keep accurate time.

So, by all means virtualise your domain controllers but don’t allow them to synchronise their clocks with the physical host. In Hyper-V this behaviour can be disabled by opening the Hyper-V Manager Console. selecting the virtual machine and clicking on Settings in the Actions pane for that virtual machine. Under the Management node select Integration Services and clear the Time Synchronization check box.

 

Click to enlarge

Click to enlarge

Click on Apply and that virtual machine will now synchronise its clock solely based on the settings within its operating system.

The second item to consider before virtualising your domain controllers concerns “snapshotting”. Snapshots allow you to take a point in time view of a server and then record differences to the virtual disk of that server over time. In this way you can “roll back” a virtual machine to the point the snap shot was taken by removing the changes made. However, this gives an issue when we consider domain controllers.

When a change is made on a Domain Controller it updates its own Update Sequence Number (USN) and, when a synchronisation is due with other domain controllers, issue the update to them. These USN’s are maintained per Domain Controller and a certain change may register on DC1 as 12345 and hold the USN of 7657622 on the far older DC2. You can see the USN on a particular Domain Controller by looking at the highestCommittedUSN value using ADSIEdit to connect to the RootDSE default naming context.

Click to enlarge

Click to enlarge

DC1 would look like above and DC2 would have the USN below, for example.
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Click to enlarge

Now, it’s a basic premise that the USN on a domain controller should only ever get bigger, and not smaller. After all, transactions can’t just disappear. Indeed, domain controllers use this USN to keep track of the updates they have received from each other. The last USN received from each replicating partner is stored in a High Watermark Vector Table on each DC. In this way, the receiving domain controller knows which was the last change it received form a replicating partner. When it next wants to replicate it sends its high watermark value to the DC it wants to replicate from (the source domain controller). The source DC then uses the information in the high watermark value to determine which objects to replicate back to the target Domain Controller. This can be represented by the following table:

Step DC USN High Watermark Value Action
1 DC1 100 200 Initial Value
DC2 200 100
2 DC1 108 200 Changes made on DC1 (New user created for example)
DC2 200 100
3 DC1 108 200 DC2 requests changes, synchronises and updates it high watermark value for DC1
DC2 200 108
4 DC1 127 200 Further changes are made on DC1
DC2 200 108
5 DC1 127 200 Only changes 109 to 127 are synchronised to DC2
DC2 200 127

 

So far so good. So, what’s the issue. The issue is that if we had taken a snapshot of DC1 at, say, step 3 and rolled back then the following would happen.

Step DC USN High Watermark Value Action
1 DC1 100 200 Initial Value
DC2 200 100
2 DC1 108 200 Changes made on DC1 (New user created for example)
DC2 200 100
3 DC1 108 200 DC2 requests changes, synchronises and updates it high watermark value for DC1
DC2 200 108
4 DC1 127 200 Further changes are made on DC1
DC2 200 108
5 DC1 127 200 Only changes 109 to 127 are synchronised to DC2
DC2 200 127
6 DC1 108 200 Active Directory database “restored” on DC1
DC2 200 127
7 DC1 119 200 Further updates made on DC1 raising its USN past the old value of 127
DC2 200 127
8 DC1 147 200 DC2 requests changes past 127 – DC1 send changes 128 to 147 – the “new” changes in the range 109 to 127 are lost and never synchronised
DC2 200 127

 

So, by restoring Active Directory from a snapshot we would run the risk of losing updates IF Active Directory allowed us to do this. Fortunately the clever guys at Microsoft have worked this out and from Windows 2003 SP1 this is not likely to happen because AD will recognise that the USN’s have become out of sequence and will refuse to allow DC1 to synchronise. You will know if this has happened to you not only because your domain will not synchronise properly but you will see an event similar to the below logged in the event viewer on the “restored” Domain Controller.

Click to enlarge

Click to enlarge

 As you can see, the only solution for this is to forcibly demote the domain controller and start again. Of course, the situation is even worse if ALL domain controllers are snapshotted and then restored. It’s perfectly possible that you can end up without an operating Active Directory environment ! So, the original question was “Should I virtualise my Domain Controllers ?” and I say that this is a decision that you have to make yourself and the risk you want to assume. However, I would suggest that a best practice is to:

  • Never synchronise Domain Controller clocks with the virtualisation host
  • Never snapshot domain controllers
  • Always have at least one (and preferably two) physical domain controllers in case you have to force demote all virtualised domain controllers

If you follow the above advice I believe the risks in virutalising DC’s are relatively low.

Virtualisation and Exchange 2010 DAG

Saturday, November 7th, 2009

Just a quick note – are you supported if you virtualise Exchange 2010 mailbox servers hosting Database Availability Groups ? The short answer is “yes”. The long answer is “Yes ….. unless you want to use Live Migration / XenMotion / VMotion … then you are NOT supported”.

To explain, DAG is a high availability strategy in and of itself. If you want to virtualise servers hosting DAG then you may but those servers should run on stand alone virtualisation hosts. Layering any sort of hardware higher availability on top of DAG high availability will invalidate your support. In truth, this shouldn’t be an issue as virtualisation only provides redundancy at the hardware level with Live Migration / XenMotion / VMotion whereas Exchange DAG provides hardware, O/S, binary and data redundancy (i.e. full redundancy) but you should take account of this in any plans you have for virtualising Exchange 2010.

Installing System Centre Virtual Machine Manager 2008 R2

Wednesday, November 4th, 2009

If you are like me then you may be a little nervous when it comes to installing a piece of software for the first time and so it’s comforting, I think, if you can see a walkthrough with an explanation or demonstration of the decision points when it comes to installing a piece of software for the first time. Below I’ve provided some screenshots and instructions for getting SCVMM up and running. My installation was performed in a lab environment with Widows 2008 Server R2 installed on my laptop providing the Hyper-V functionality so that the hypervisor can have access to the virtualisation extensions of the processor (i.e. hyper-v will work). I’ve then created two virtual machines, scvmmdc as a domain controller and scvmm to run SCVMM and control hyper-v on my laptop as a host. True, it’s now what you would expect to see in production but it does give you an idea of how to install the software.

The first thing you will note is that I’m not installing a full install to a clustered sql server and, equally, I have not clustered SCVMM to make it highly available … both of these things being best practice for a full multi host production environment. You can, of course, get away without doing either of these things in production as you can still control clustered hyper-v from the built in server administration tools, it’s just that you won’t have access to SCVMM if your single server is not up and running. So, the more physical hosts you have, the “better” practice it is to provide high availability for SCVMM.

The first thing to note after installing the setup disk is that the very first link gives you access to the SCVMM help file which gives excellent advice as to sizing the solution, supported SQL, required software etc (the Setup Overview link).

Straight from that guide, the software requirements are:

Software requirement Notes
A supported operating system For more information, (generally 2003 SP2 and later).
Windows Remote Management (WinRM) This software is included in Windows Server 2008 and the WinRM service is set to start automatically. If the WinRM service is stopped, the Setup Wizard starts the service.
Microsoft .NET Framework 3.0 This software is included in Windows Server 2008. If this software has been removed, the Setup Wizard automatically adds it (i.e. no need to download unless you want the latest version – always patch afterwards though).
Windows Automated Installation Kit (WAIK) 1.1 If this software has not been installed previously, the Setup Wizard automatically installs it (i.e. no need to download unless you want the latest version – always patch afterwards though).

If you use the same computer for your VMM server and your VMM database, you must install a supported version of Microsoft SQL Server.

Supported versions of SQL are

  • SQL Server 2008 Express Edition
  • SQL Server 2008 (32-bit and 64-bit) Standard Edition
  • SQL Server 2008 (32-bit and 64-bit) Enterprise Edition
  • SQL Server 2005 Express Edition SP2
  • SQL Server 2005 (32-bit and 64-bit) Standard Edition SP2
  • SQL Server 2005 (32-bit and 64-bit) Enterprise Edition SP2

If you do not specify a local or remote instance of SQL then the Setup Wizard will install SQL Server 2005 Express Edition SP2 on the local computer. The Setup Wizard also installs SQL Server 2005 Tools and creates a SQL Server instance named MICROSOFT$VMM$ on the local computer. To use SQL Server 2008 for the VMM database, SQL Server Management Tools must be installed on the VMM server. If you use Express Edition then SCVMM will not allow reporting and the database size is limited to 4GB.

After reading the pre-requisites we can prepare the server and domain to host SCVMM. The domain needs to be at Windows 2003 domain level as a minimum. Equally, if the SCVMM server is to host the self service portal then IIS needs to be installed and configured. For Windows 2003 this is a simple matter of installing the Application Server role. For Windows 2008 and above add the Web Server (IIS) role and ensure the following role services are selected:

  • Static Content
  • Default Document
  • Directory Browsing
  • HTTP Errors
  • ASP.NET
  • .Net Extensibility
  • ISAPI Extensions
  • ISAPI Filters
  • Request Filtering
  • IIS 6 Metabase Compatibility
  • IIS 6 WMI Compatibility

We can then check the server for suitability for hosting SCVMM. This can be done locally or form a remote machine but whichever machine is being used for this task, that machine needs to have the Microsoft Baseline Configuration Analyzer installed which can be downloaded from http://go.microsoft.com/fwlink/?LinkId=97952. Once the MBCA has been installed we can then click the link for the VMM Configuration Analyzer. This will allow you to download the analyzer tool to your local machine and pre-check the machine for suitability for hosting SCVMM.

When starting the Analyzer tool from the start menu we have the following choices (SCVMM is the name of my lab machine). The tool should really be run in the context of an account that is a domain administrator in order that the tool can accurately check the domain level.

After clicking Scan and waiting a short while you will be presented with a report for which you will need to correct any errors.

Once all errors are resolved we can move onto installing the SCVMM software. Simply click on “SCVMM Server” under the setup section of the welcome screen. Setup will extract some temporary files and then begin the installation routine. Read and accept the license terms if you agree with them and wish to proceed.

I recommend that you participate in the customer experience program if you wish to see Microsoft improve their software for you and all other users.


Complete the User registration details according to your corporate standards.

Complete the prerequisites check and, if passed, click on Next.

Select where to install the software binaries.

As I don’t have a separate SQL server in my lab I chose to install SQL Express locally on my server.

I created a new folder called “Library” and changed the path for the library share to used that new location. In the normal course of events I would usually put this on a drive other than C to allow for growth.

While it is a best practice to change the port numbers used (one for security and two, because you have to uninstall and reinstall SCVMM if you want to change the ports later) I have left them at their defaults for my lab. Similarly, it is a security best practice to leave the service account as the system account. A network account should be used if SCVMM is being installed in a clustered environment where SCVMM is itself clustered.

At the summary of settings page click on Install to proceed.

The software and pre-requisite software will then be installed.

Finally, once the installation has completed select Close to check for any SCVMM updates.

This will have installed SCVMM server. Next, we need to install the Administrators Console. After any required patching, reboot the server and start setup from the CD once more and select VMM Administrator Console in the setup section. Once again temporary files will be extracted and the installation process will begin. As before, we first read and accept the license agreement if we want to proceed.

There is no need to join the Customer Experience Improvement Program as this screen will pick up the choice made when installing SCVMM server (this choice is available if installing the administrative console onto an administrators workstation).

Complete the prerequisites check and, if passed, click on Next.

Select the installation location and click on Next.

Next, we assign the port that we want the console to use to communicate with the SCVMM Server. This is the port that you assigned when installing SCVMM Server above. The port setting that you assign for the VMM Administrator Console must identically match the port setting that you assigned for the VMM Administrator Console during the installation of the VMM server or communication will not occur.

On the Summary of Settings page, if all settings are fine then click on Install.

The installation will then proceed.

Once again, click on Close and check for any updates to the software.

Once any updates have been installed and the server has been rebooted we can proceed to install the optional VMM Self-Service Portal. The Self Service Portal allows identified users to create and manage virtual machines within a Hyper-V or VMWare environment where SCVMM is managing VMWare hosts. To begin the install simply click on the VMM Self-Service Portal link under the Setup section of the welcome page. Once again temporary files will be extracted and the installation process will begin. As before, we first read and accept the license agreement if we want to proceed.

Complete the prerequisites check and, if passed, click on Next (remember, IIS must have been installed to install this service).

We can then choose where to install the application binaries. Here, I have chosen the default location for my lab. In a production environment I would move these to a drive other than C.

Next we tell the installation what port we would like users to connect to the self-service portal over. Generally this is port 80 but if another web site is being hosted on the server then we can either select a different port or, more usually, set a different host / web address to be used by the solution by way of host headers. If port 80 is already in use (by the default web site for example) then we receive the error message below.

I’ve used the hostname selfservice and registered this in my DNS servers as a host (A) record to enable clients to find the site. Additionally, we once again have to connect to our SCVMM server and need to enter the port number chosen earlier for connections. We can then click on Next to move to the next screen.

On the Summary page we can now select Install if we are happy with all of our settings.

Once again we click on Close and check for any updates to the software.

Once the installation is complete we can once again check for any updates and reboot the server to ensure that all services start cleanly (checking the event log for any issues on startup).

Once restarted you can take time if necessary to harden your self-service portal environment by deploying SSL (to encrypt traffic), using integrated logon (to prevent users having to enter passwords) and disabling unwanted ISAPI filters. The full guide on recommended hardening measures can be found at http://go.microsoft.com/fwlink/?LinkId=123617.

If you have followed these steps you should now have a fully functional SCVMM server which can be connected to your Hyper-V or VMWare servers. Connecting to Hyper-V couldn’t be simpler. When you add a virtual machine host or library server that is in an Active Directory domain, SCVMM remotely installs an SCVMM agent on the Hyper-V host. The SCVMM agent deployment process uses both the Server Message Block (SMB) ports and the Remote Procedure Call (RPC) port (TCP 135) and the DCOM port range. You can use either SMB packet signing or IPSec to help secure the agent deployment process. You can also install SCVMM agents locally on hosts, discover them in the SCVMM Administrator Console, and then control the host using only the WinRM port (default port 80) and BITS port (default port 443). Even though we do not need to install the Local Agent manually as all of our servers reside in a domain I run through the procedure for installation below. First we insert the SCVMM disc into our hyper-v server (or map a drive to it) and start the setup routine and then click on Local Agent under setup. The installation of the Local Agent will then begin.

Accept the terms of the agreement to continue.

Select the installation path.

Change the ports the Hyper-V server will use to connect to the SCVMM server to those set earlier when SCVMM was installed.

Our server is not sitting in a DMZ – if it were we could encrypt traffic between the Hyper-V server and SCVMM.

You can then continue to Install the Agent

Click on Finish when completed.

Next we need to start the SCVMM Admin console on the SCVMM server by double clicking the link created on your desktop or by using the link in the Start menu.

From the Outlook like interface we can select the Hosts section and from there we can create a new host group if we have a number of physical Hyper-V or VMWare hosts we would like to control. For our purposes we’ll just use the All Hosts group. On the right hand side (Actions column) we can select Add Host.

In my lab the Hyper-V server is part of my domain as it would have to be if we were running a Hyper-V cluster and so we select the first choice and enter the domain administrator credentials to allow SCVMM access to the Hyper-V host.

Next, type in the name of the physical server running Hyper-V or browse for it in Active Directory. Note: Hyper-V does not need to be installed on the host at this point – if it is not then SCVMM will install and activate the role on the target server and reboot it.

Add the host machine to a host group.

Add a default path where Virtual Machines should be created on this host. When you add a stand-alone Windows Server-based virtual machine host as we are doing here to Virtual Machine Manager (SCVMM), you can add one or more virtual machine default paths, which are paths to folders where SCVMM can store the files for virtual machines that are deployed on the hosts. However, For a Hyper-V or VMWare cluster the default path is a shared volume on the cluster that SCVMM automatically creates when you add the host cluster. When you are adding the host cluster, you cannot specify additional default paths in the Add Host Wizard.

We then get asked to confirm the settings and can select to add our host.

Once added a job will auto-run to add the host followed by a further series of jobs to add in any already configured Virtual Machines running on that host into SCVMM.

You should now be able to control your Hyper-V host using SCVMM and configure the self-service portal for your users.

How should I license my virtualised environment ?

Tuesday, November 3rd, 2009

Many people know that if you purchase a copy of Windows Server 2008 R2 Enterprise Edition then you get to run 4 copies of Enterprise or down level versions in a virtualised environment on that physical host for which the Enterprise license was purchased. This is true even if you don’t install Enterprise on the physical host. That is, you can install XenServer or VMWare and still take advantage of this fantastic deal.

What you may not be aware of though is that you can also but Windows Server 2008 R2 Datacenter Edition and run an unlimited number of Windows Server guest VM’s on that physical host. Datacenter is licensed per processor socket (not core) and you have to license a minimum of 2 sockets (processors) in the physical server but, and here’s the thing, with hexa (6) and octo (8) core processors now on the market then, with 2 octo-core processors and one physical core assigned to each VM then you can run 16 VM’s on a single host for the price of 2 Datacenter Edition licences or 4 Enterprise Edition licences. If you go for even higher densities then the gap widens still further. With the difference in price between versions being only a couple of hundred bucks then there are savings to be made in even the smaller virtualised data centers.

But, how do you tell which is the right choice for you ? Microsoft have published an online tool to help you out. Simply type in the price you pay for Enterprise, Standard and Datacenter Editions, the number of processors per server and the average number of VM’s per server and the calculator will tell you which is the cheaper option to go for.

You can find this tool online at http://www.microsoft.com/windowsserver2008/en/us/hyperv-calculators.aspx.

How to tell if your PC supports XP Mode on Windows 7

Monday, November 2nd, 2009

Thinking of rolling out Windows 7 ? Then it could be that you will want to run XP Mode for backwards compatibility of older applications. XP mode allows you to run applications in a Windows XP SP3 virtual machine and present the application to the user as though it is running locally on the Windows 7 machine. Well, if you have a fleet of machines in your organisation then its likely you have purchased over time and don’t know which support hardware assisted virtualisation and which don’t. Microsoft have now bought out a simple tool that you can run on a logged on machine (admin privileges using run as required of course) that will tell you if the processor supports virtualisation and, more importantly, if its enabled for virtualisation.

There’s also a command line giving the opportunity to run a start up script and write a log file centrally so that you can see which machines can support this feature and which can’t.

You can download the free tool from http://go.microsoft.com/fwlink/?LinkId=163321.

Best Practices for Virtualising Exchange

Sunday, November 1st, 2009

Hold on to your hats. Microsoft are drawing a line in the sand and broadcasting what they believe are the best practices for virtualizing Exchange servers. Its an online broadcast and anyone can attend. Its due this Wednesday 4th November and you can sign up here.