Windows Server 2008 (R2) blog by Kurt Roggen [BE]

PowerShell 2.0 brings some great new management functionality such as:

• Remoting: lets you run commands on one or more remote computers from a single computer that is running Windows PowerShell. PowerShell remoting allows for multiple ways of connecting, including interactive (1:1), fan-out (1:many) and fan-in (many:1 by using the IIS hosting model).
• New cmdlets: over 100 built-in cmdlets, enabling you to do computer-related tasks, event log and performance counter management task.

PowerShell version 2.0 is bundled into the Windows Management Framework.

The Windows Management Framework makes some updated management functionality of Windows 7 and Windows Server 2008 R2 available to be installed on Windows XP, Windows Server 2003, Windows Vista, and Windows Server 2008.

Windows Management Framework contains 3 components:

• Windows Remote Management (WinRM) 2.0
• Windows PowerShell 2.0
• Background Intelligent Transfer Service (BITS) 4.0.

Using WSUS (part of Windows Server 2008 R2 as a server role), you can import the PowerShell 2.0 package and approve it for installation on your Windows Server 2008, Windows Server 2003, Windows Vista and Windows XP machines.

Import updates directly into WSUS

Add selected updates to download basket

Once the updates are imported into the WSUS infrastructure, you can approve the update on the required computer groups containing your targeted machines.

 
Approve the imported updates

NOTE: Be aware that the Windows Management Framework is about 30-35 MB in size.  If bandwidth is an issue or if you are dealing with a serious amount of clients, you may want to throttle the bandwidth used by the Background Intelligent Transfer Service (BITS) which is used as transport mechanism by the Windows Update engine.

More about that another time…

Related reading:

• Windows Management Framework (Windows PowerShell 2.0, WinRM 2.0, and BITS 4.0)

To be able to troubleshoot the Windows Deployment Services, it is crucial to first understand the overall WDS architecture, since you can activate logging at most levels in the architecture.  We did that in previous post.

The second step, is drilling down into these components and their logging/debugging facilities.

Looking at WDS Configuration

To get a quick overview of your current WDS configuration, type the following command:

C:\> wdsutil /get-server /show:config

For more information, read my previous blog post.

Looking at WDS Eventlogs

If the multicast transmission still start automatically too soon, I suggest enabling logging for WDS Events:

1. Open Server Manager
2. Select Diagnostics -> Event Viewer -> Applications and Services Logs
3. Navigate to Microsoft\Deployment-Services-Diagnostics
4. Right-click the Admin log and choose Enable log
5. Right-click the Operational log and choose Enable log

Reproduce the issue and check the event logs.

Looking at WDS Logging

• WDS Server-side - %windir%\Tracing\wdsserver.log – Set REG_DWORD EnableFileTracing = 1
• WDS Mgmt - %windir%\Tracing\wdsmgmt.log
• WDS MMC snapin - %windir%\Tracing\wdsmmc.log
• Client-side - X:\Windows\Panther, $Windows.~BT\Sources\Panther, %systemdrive%\Windows\Panther

Related reading:

• KB936625 - How to enable logging in Windows Deployment Services (WDS) in Windows Server 2003 and in Windows Server 2008 (R2)
• TechNet TechCenter - Troubleshooting WDS Performance Problems

The other day, I got asked about WDS (Windows Deployment Services) troubleshooting…
To be able to troubleshoot the Windows Deployment Services, it is crucial to first understand the overall WDS architecture, since you can activate logging at most levels in the architecture.

Understanding the WDS Architecture

WDS Server Service
The WDSServer service is the main server-side service for Windows Deployment Services. It provides basic service functions such as memory management, thread pooling, and network interface binding in an effort to support its hosted subcomponents, known as providers. The providers provide the true functionality associated with WDSServer. There are five providers included with the default (Deployment Server) installation:

• PXE provider
• PXE server
• Image server
• Multicast server
• TFTP server

WDS PXE Server
The Pre-Boot Execution Environment (PXE) server is used by Windows Deployment Services to provide network boot programs to client computers. PXE technology is a standard created by Intel that establishes a common and consistent set of pre-boot services within the boot firmware. The end goal is to enable a client to perform a network boot and receive a network boot program (NBP) from a network boot server.

WDS PXE Provider
The Pre-Boot Execution Environment (PXE) provider for Windows Deployment Services provides client boot services over the network. It registers itself with the WDSServer service (the main server-side service of the Windows Deployment Services solution) and requests a remote procedure call (RPC) endpoint.

PXE technology is a standard created by Intel that establishes a common and consistent set of pre-boot services within the boot firmware. The end goal is to enable a client to perform a network boot and receive a network boot program (NBP) from a network boot server.

WDS Image Server
The Windows Deployment Services image server stores and maintains the installation and boot images. The image server is the module used by the Windows Deployment Services client when it is communicating with the server. The server registers a remote procedure call (RPC) endpoint for communication between the client and the server.

WDS Multicast Server
The multicast server deploys an image to a large number of client computers concurrently without overburdening the network. When you create a multicast transmission for an image, the data is sent over the network only once, which can drastically reduce the network bandwidth that is used.

WDS Multicast Content Provider
The multicast server uses a content provider to transmit the data from the server to the client. The Windows Deployment Services content provider can transfer any file over a multicast transmission. This content provider connects the multicast transmission or namespace to the data that has been requested by clients.

WDS TFTP Server
You use the Windows Deployment Services Trivial File Transfer Protocol (TFTP) server to download the files that are needed to do a network boot using the Pre-Boot Execution Environment (PXE). PXE technology is a standard created by Intel that establishes a common and consistent set of pre-boot services within the boot firmware. The end goal is to enable a client to do a network boot and receive a network boot program (NBP) from a network boot server.

The TFTP server downloads boot files such as Pxeboot.com, Wdsnbp.com, Bootmgr.exe, and Default.bcd, as well as the boot image that contains Windows Preinstallation Environment (Windows PE).

Related reading:

• Technet - Windows Deployment Services Server Components

I’m proud to announce and pleased to see that Microsoft has recognized all my contributions made in the past, by awarding me with the MVP title in “Management Infrastructure” for the 3rd year in a row.

In the end, nothing really changes… I will keep doing what I have been doing so far: sharing knowledge and information. 

Hope you enjoy it, too!!
Kurt

I've been using PowerShell for a while now but it still hasn't replaced the command prompt for me yet, even though it is extremely powerful!!  I have been using the Command Prompt From Here a lot to make it easier to open up a command prompt at a specific folder location from the Explorer.  So now I added some settings to the registry that will do the same but with PowerShell instead.

Here is the registry file for making the entry in Explorer:

Windows Registry Editor Version 5.00

[HKEY_CLASSES_ROOT\Directory\shell\PowerShell]
@="Open PowerShell window here"

[HKEY_CLASSES_ROOT\Directory\shell\PowerShell\Command]
@="\"C:\\Windows\\System32\\WindowsPowerShell\\v1.0\\powershell.exe\" -NoExit -Command [Environment]::CurrentDirectory=(Set-Location -LiteralPath:'%L' -PassThru).ProviderPath\""

Related reading:

• Tips & Tricks #2 – CMD: Command Prompt From Here

• Tips & Tricks #1 – UAC: Shortcut Key Using mouse and/or keyboard

When doing a P2V (Physical To Virtual) by moving a workload from the physical world into the virtual world, you actually don’t want those specific IHV’s network, storage and other drivers/services starting up at next boot time, because it will cause a long delay to fail all these drivers/services.  They no longer make sense in your virtual environment, where synthetic or legacy drivers take over…

There are tools out there, that assist you in removing these drivers and services (once you are on the other side) such as the HP Proliant Support Pack Cleaner tool.

But know that when doing a P2V with SCVMM, there is this undocumented manifest (BlockList.xml) that disables Services and/or Drivers during the P2V process.

On the SCVMM server, in the following location C:\Program Files\Microsoft System Center Virtual Machine Manager 2008 R2\VMMData, you can find BlockList.xml.
In this file, you can list all services and drivers to disable in a virtual machine during the P2V process.
The syntax of this file is simple and uses the short name for services and drivers.

However editing this file is not supported by Microsoft…

<?xml version="1.0" encoding="utf-8" ?>
<BlockList> 
   <!-- services to disable –>
   <Service>
      <Name> </Name>
   </Service>
   <!-- drivers to disable –>
   <Driver>
      <Name> </Name>
   </Driver> 
   <!-- programs to disable –>
   <Program>
      <Name> </Name>
   </Program>
</BlockList>

When dealing with HP hardware, you may want to exclude following drivers, services and programs:

For use with HP hardware/software

For use with Dell hardware/software

Still in progress…

For use with IBM hardware/software

Still in progress…

As you seen I’m still in the process of completing the lists for both Dell and IBM hardware, so fee free to sent me your feedback on drivers and services to disable.

Anyhow, it would definitely avoid messing around with the CLI using sc.exe

sc [\\server] query type= driver
sc [\\server] query type= service

sc [\\server] config start= disabled

Related reading:

• Frequently Asked Questions: P2V and V2V Conversions in SCVMM
• WMI- P2V conversion may fail with error ID 3101 and "Unknown error 0x80041001"
• BITS - P2V together with System Center Virtual Machine Manager 2008 may fail with error 3154 (0x8099319E) or error 13252 (0x809933C4)

To get a quick overview of your current WDS configuration, use the WDS CLI and type the following command:

C:\> wdsutil /get-server /show:config [/server:yourRemoteServer]

To get a more detailed overview of your current WDS configuration, type the following command:

C:\> wdsutil /get-server /show:all /detailed

Here’s a quick output of such a configuration listing:

C:/> WDSUTIL /get-Server /server:SEA-WDS /show:Config

Windows Deployment Services Management Utility [Version 6.0.6001.18000]
Copyright (C) Microsoft Corporation. All rights reserved.

SETUP INFORMATION FOR SERVER BXL-WDS
[-----------------------------------------------------------------------------]

Server State:
     OS version: 6.0
     WDS operational mode: Native

Installation State:
     REMINST location: W:\Images
     REMINST share up-to-date: Yes
     Boot files installed:
         x86  - Yes
         x64  - No
         ia64 - No

[-----------------------------------------------------------------------------]

CONFIGURATION INFORMATION FOR SERVER BXL-WDS
[-----------------------------------------------------------------------------]

Server Authorization:
     Authorization state: Not Authorized

Answer Policy:
     Answer clients: Yes
     Answer only known clients: No
     Response delay: 0 seconds

Directory Services Use Policy:
     Preferred DC: 
     Preferred GC: 
     Prestage devices using MAC: No
     New machine naming policy: %61Username%#
     Domain search order: Global Catalog Only
     New machines join domain: Yes

New Machine OU:
     OU type: Server Domain
     OU: CN=Computers,DC=contoso,DC=com

DHCP Configuration:
     DHCP service status: Not Installed
     DHCP option 60 configured: <Not Applicable>

Pxe Bind Policy:
     Use DHCP ports: Yes
     Rogue detection: Disabled
     RPC port: 5040

Interface Bind Policy:
     Policy: Exclude Registered
     Registered interfaces:

Boot Program Policy:
     Allow N12 for new clients: No
     Architecture discovery: Enabled
     Reset boot program: No
     Default boot programs:
         x86  - boot\x86\pxeboot.com
         x64  - boot\x64\pxeboot.com
         ia64 - boot\ia64\bootmgfw.efi
     Default N12 boot programs:
         x86  - boot\x86\pxeboot.n12
         x64  - boot\x64\pxeboot.n12
         ia64 - boot\ia64\bootmgfw.efi

Banned GUIDs List:

Boot Image Policy:
     Default image type for x64 clients: Both
     Default boot images:
         x86  - 
         x64  - 
         ia64 -

WDS Client Policy:
     Logging policy:
         Enabled: No
         Logging level: Info

     Unattend policy:
         Enabled: No
         Command-line precedence: No
         WDS unattend files:
             x86  - 
             x64  - 
             ia64 -

OSChooser Policy:
     Menu name:

Server Auto-Refresh Policy:
     Refresh period: 900 seconds

BCD Refresh Policy:
     Enabled: No
     Refresh period: 60 minutes

Auto-Add Policy:
     Policy: Disabled
     Poll interval: 10 seconds
     Max retry count: 2160 times
     Message: 
     Retention period:
         Approved devices: 30 days
         Other devices: 1 days
     Defaults for x86:
         Referral server: 
         Boot program path: 
         WDS client unattend file path: 
         Boot image path: 
         User: Domain Admins
         Join rights: Full
         Join domain: Yes
     Defaults for x64:
         Referral server: 
         Boot program path: 
         WDS client unattend file path: 
         Boot image path: 
         User: Domain Admins
         Join rights: Full
         Join domain: Yes
     Defaults for ia64:
         Referral server: 
         Boot program path: 
         WDS client unattend file path: 
         Boot image path: 
         User: Domain Admins
         Join rights: Full
         Join domain: Yes

WDS PXE Providers:
     Name: BINLSVC
     Path: C:\Windows\system32\binlsvc.dll
     Order: 1
     Critical: Yes

WDS Transport Server Policy:
     IPv4 Source: Range
         Start IP: 239.0.0.1
         End IP: 239.0.0.254
     Start Port: 64001
     End Port: 65000
     Network Profile: 100Mbps

[-----------------------------------------------------------------------------]

The command completed successfully.

How to enable it?  Simply go to HKLM\SYSTEM\CurrentControlSet\Services\WDSServer\Providers\WDSPXE\Providers\BINLSVC and set AllowServerSelection to 1.

After restarting the Windows Deployment Service, you get the server selection option by pressing F11 and the PXE client will now discover all PXE Servers which have this registry key set and allow you to select which one you want to use.

Initial PXE Boot Screen

PXE/WDS discovery process

I came across a WDS problem which seemed familiar at first, but in the end turned out to be something “unexpected”:
“ProxyDHCP: No reply to request on port 4011”

Typically, you would end up looking at articles like KB259670 (PXE clients computers do not start when you configure the Dynamic Host Configuration Protocol server to use options 60, 66, 67)… but this was different some clients/servers worked and some didn’t…

Symptom

When initiating a PXE Boot to the WDS server, the client receives a IP address from the DHCP server, but eventually times out with error “ProxyDHCP: No reply to request on port 4011”
However, other clients/servers have no problem PXE booting to the WDS server and getting boot/installation images.

Cause

There is a database named “Auto-Add Devices database”, used when you are performing the “Pending Devices” actions.  It stores the records for machines with a “pending devices” status and/or devices with an “approved” status.

Solution

The computer GUID is marked as rejected in the Auto-Add database. After a computer has been marked as rejected, the computer will not be able to PXE boot.
You can clear the entry in the Auto-Add database by deleting all pending computer records (by running wdsutil /Delete-AutoAddDevices /DeviceType:RejectedDevices) or enabling the record to be purged automatically (as mentioned above).

To delete computers that are pending, rejected or approved from the Auto-Add database, use wdsutil /Delete-AutoAddDevices using the syntex below:

WDSUTIL /Delete-AutoAddDevices [/Server:<Server name>] /DeviceType:{PendingDevices | RejectedDevices |ApprovedDevices} 

More Information

The records in the Auto-Add Devices database are purged every 24 hours and the cleanup of any devices with an approved status occurs every 30 days.
You can look at these intervals using the WDS CLI under “Configuration Information - Auto-Add Policy”

C:\> wdsutil /get-server /show:config [/server:yourRemoteServer]

These values can be changed using the WDS CLI

C:\> wdsutil /set-server /AutoAddPolicy /RetentionPeriod /Approved:<Time in days> /Others:<Time in days>

The Auto-Add Devices database (named Binlsvcdb.mdb) can be found in the RemoteInstall\MGMT folder. The database is created by BINLSVC the first time the pending devices policy is enabled. 

Related reading:

• KB259670 - PXE clients computers do not start when you configure the Dynamic Host Configuration Protocol server to use options 60, 66, 67
• KB244036 - Description of PXE Interaction Among PXE Client, DHCP, and RIS Server
• How to Manage Client Computers - Auto-Add Database section

Using Windows Deployment Services, we talked about approving pending computers.  You might also have noticed on the “pending” screen an empty message from the administrator.

How can you set a message from the administrator?

On the WDS server from a command prompt type:

WDSUtil /set-server /AutoAddPolicy /Message:"To contact your network administrator, please dial 123-4567“

Not so long ago, I wrote about the new Best Practice Analyzer for Hyper-V being available.  But what does it check?

It checks 3 areas:

• Prerequisites: identify gaps in Hyper-V configuration that should be addressed before administrators run a Best Practices Analyzer scan on Hyper-V for the first time.
• Configuration: identify settings that might require modification for Hyper-V to perform optimally. Configuration rules can help prevent setting conflicts that can result in error messages or prevent Hyper-V from carrying out its prescribed duties in an enterprise.
• Operations : identify best-practice–related, possible causes of a server role’s failure to carry out its prescribed tasks in an enterprise. An example of a violation of operation rules is the use of snapshots on a virtual machine that runs a server workload in a production environment.

For more information: Microsoft TechNet: Best Practices Analyzer for Hyper-V

Related reading:

• Ben Pearce’s Blog - Hyper-V Best Practice Analyzer - What does it check?

• Hyper-V Best Practices Analyzer is now available for Windows Server 2008 R2

• New Best Practice Analyzers (7) are available for Windows Server 2008 R2

Using Windows Deployment Services, you can boot a new (read: unknown) client and "name and approve" it from the WDS console.  A (named) computer object with the right GUID gets created in Active Directory and the machine starts building.

Symptom

When you select “Name and Approve” on a pending device, you might get an “Access Denied”.

Cause

The actual account of an approved pending computer is created by using the server’s authentication token, not using the token of the administrator who is performing the approval.

Solution

Therefore, in ADDS, you must grant rights to the Windows Deployment Services server’s account (WDSSERVER$) to create computer account objects for the containers and OUs where the approved pending computers will be created.

To grant permissions to approve a pending computer

1. Open Active Directory Users and Computers.
2. Right-click the OU where you are creating prestaged computer accounts, and then select Delegate Control.
3. On the first screen of the wizard, click Next.
4. Change the object type to include computers.
5. Add the computer object of the Windows Deployment Services server, and then click Next.
6. Select Create a Custom task to delegate.
7. Select Only the following objects in the folder. Then select the Computer Objects check box, select Create selected objects in this folder, and click Next.
8. In the Permissions box, select the Write all Properties check box, and click Finish.

More information

There is also another database named “Auto-Add Devices database”, used when you are performing the “Pending Devices” actions.  It stores the records for machines with a “pending devices” status and/or devices with an “approved” status.  The records in the Auto-Add Devices database are purged every 24 hours and the cleanup of any devices with an approved status occurs every 30 days.

The Auto-Add Devices database (named Binlsvcdb.mdb) can be found in the RemoteInstall\MGMT folder. The database is created by BINLSVC the first time the pending devices policy is enabled. 
Read and write permissions to the C:\RemoteInstall\MGMT folder (containing the Binlsvcdb.mdb) are also required.

Related reading:

• Technet: WDS – Required permissions

Q: What is the option “Enable spoofing of MAC addresses” on a virtual network adapter?
A: A virtual network adapter can send/receive packets containing any MAC address.  Equivalent of putting adapter in promiscuous mode.
More information: http://blogs.technet.com/jhoward/archive/2009/05/21/new-in-hyper-v-windows-server-2008-r2-part-2-mac-spoofing.aspx

Q: What is the “Processor Compatibility” feature?
A: Allows more hardware flexibility/mobility between Hyper-V hosts when moving VMs by reducing the CPU instruction set to a common level set. Works only within same CPU family (Intel-to-Intel, AMD-to-AMD). Is a key feature for flexible Live Migration.
More information: http://blogs.msdn.com/b/virtual_pc_guy/archive/2009/06/09/processor-compatibility-in-hyper-v-r2.aspx

Q: What is the “Network Optimizations” feature?
A: With VMM 2008 R2, you can take advantage of network optimization capabilities that are available on hosts that are running Windows Server 2008 R2 Hyper-V. VMM 2008 R2 supports both the Virtual Machine Queue (VMQ) and TCP Chimney features, which improve network performance for virtual machines. Network Optimizations is configurable at the VM level and is visible for capable virtualisation hosts during the virtual machine Intelligent Placement wizard.
More information: http://technet.microsoft.com/en-us/library/ee236499.aspx

Q: What is VMQ (Virtual Machine Queue)?
A: Network adapters that support the VMQ (Virtual Machine Queue) feature can create a unique network queue for each virtual network adapter and then connect that queue directly to the virtual machine’s memory. This connection routes packets directly from the hypervisor to the virtual machine, bypassing much of the processing in the virtualization stack.

Q: Can I use SCVMM to insert my Hyper-V host into a the Hyper-V cluster?
A: No, you still need to complete most cluster related tasks using the Failover Cluster Manager console.

Q: What is Storage Quick Migration (SQM)?
A: Allows the migration of the storage of VM from one location to another with under 1 minute downtime in most cases. The virtual machine can remain running for the almost the entire duration of the transfer of its (read-only) virtual disks from once storage location to another.  The virtual machine is put into saved-state for a short period to migrate its memory state and associated differencing disks.
More information: http://blogs.technet.com/b/virtualization/archive/2009/06/25/system-center-virtual-machine-manager-2008-r2-quick-storage-migration.aspx

Q: What are CSV (Clustered Shared Volumes)?
A: Allows for storing multiple Hyper-V VMs, their configuration, snapshots, etc… per LUN by providing coordinated distributed access to a cluster shared volume through a single consistent namespace (C:\ClusterStorage) which is shared among all nodes in the cluster. CSV avoids the “LUN management nightmare”.
More information: http://blogs.msdn.com/b/clustering/archive/2009/03/02/9453288.aspx

Q: Does SCVMM 2008 R2 support CSV?
A: Yes, SCVMM even recognizes the difference between an owner (coordinator) node and non-owner node when deploying VMs to the Hyper-V cluster nodes. When deploying a VM, the VHD is deployed to the Hyper-V CSV owner (coordinator) node first, while the VM is created on the host selected during the VM creation wizard (Intelligent Placement) within SCVMM.

Q: I’m using diskshadow.exe to backup my virtual machines using the Hyper-V VSS Writer.  Can I also use it with CSV disks?
A: No, unfortunately DiskShadow is not compatible with CSV in Win2008 R2. You can only do CSV backups from coordinator node safely which is the only node that has access to the (Hyper-V) VSS writer. Windows Server Backup does also not support backing up virtual machines on Cluster Shared Volumes (CSV volumes).

Related reading:

• System Center Virtual Machine Manager (VMM) Q&A – Part 1

Here’s an overview of some of the most raised SCVMM questions and their answers:

Q: What is CPU Type in SCVMM 2008 R2 VM Processor Hardware Profile?
A: Just used for Intelligent Placement of virtual machines – not the actual vCPU 
More information: http://blogs.technet.com/mghazai/archive/2009/12/02/what-is-cpu-type-in-scvmm-2008-r2-vm-processor-hardware-profile.aspx

Q: What is the purpose of SCVMM Network Location and Tag?
A: Matching virtual networks during virtual machine deployment/migration 
More information: http://blogs.technet.com/apb/archive/2009/03/20/the-purpose-of-scvmm-network-location-and-tag.aspx

Q: How can I quickly/easily configure my Hyper-V running in a workgroup to allow remote administration using Hyper-V Manager?
A: Download HVremote
More information: http://blogs.technet.com/jhoward/archive/2008/11/14/configure-hyper-v-remote-management-in-seconds.aspx

Q: What’s the difference between “Host Reserve” and “Cluster Reserve”
A: Host Reserves define how much of a host’s resources are to reserved for the host operating system in terms of CPU, RAM, disk space, IOPS, network. 
Cluster Reserve specifies the number of node failures a cluster must be able to sustain while still supporting all virtual machines deployed on the host cluster. 
More information: http://fawzi.wordpress.com/2009/04/13/scvmm-host-reservers-and-cluster-reserve/

Q: Can I use DFS on my VMM Library?
A: Yes, but VMM 2008 is not DFS-aware; neither is it location-aware. There is no special logic in VMM for DFS-R and/or DFS-N. Both are unsupported and can lead to some known issues.
More information: http://blogs.technet.com/chengw/archive/2008/08/26/dfs-on-vmm-library.aspx

Q: What does 'over-committed' cluster status mean?
A: The “cluster reserve” specifies the number of node failures a cluster must be able to sustain while still supporting all virtual machines that are currently deployed on the clustered hosts.  If this cluster reserve cannot be met, the cluster is “over-commited”.
More information: http://blogs.technet.com/mbriggs/archive/2009/12/02/what-does-over-committed-status-really-mean.aspx

Q: Can VMM be installed inside a VM?
A: Installing VMM in a virtual machine is a fully supported scenario.  Consider the flexibility of the VM (snapshots, live migration) but also consider moving the VMM Library share(s) out of the VM (for growth and performance reasons). Also exclude the VM from receiving and acting on PRO-tips.
More information: http://blogs.technet.com/mbriggs/archive/2009/05/22/should-vmm-live-inside-a-vm-or-on-a-physical-server.aspx

Q: Can I reduce the number of VMM PS task/jobs that are kept in the VMM database?
A: Yes, just configure the TaskGC (DWORD) in “HKLM\Software\Microsoft\Microsoft System Center Virtual Machine Manager Server\settings\SQL” to the number of days you want to keep.
More information: http://blogs.msdn.com/robertvi/archive/2009/05/25/scvmm-service-may-take-up-lots-of-memory.aspx

Q: Can I share (remote) ISO files in VMM with Hyper-V?
A: Yes, use constrained delegation to enable the CIFS protocol to be accessed on your library server by the Hyper-V host(s) and use a domain account as VMM service account.
More information: http://blogs.technet.com/m2/archive/2009/08/15/how-to-properly-share-iso-files-in-vmm-with-hyper-v.aspx

Q: Can I backup the VMM database?
A: Yes, using both GUI and/or CLI. Using the VMM Administrator console or using the VMM PowerShell cmdlet called “Backup-VMMserver”
More information: http://technet.microsoft.com/en-us/library/bb963730.aspx

Q: What’s the difference between “Maintenance Mode” and “Host is unavailable for Placement” option at the VMHost?
A: When you start the “Maintenance Mode” on a VMHost, all VMs are (live) migrated away from that VMHost (where possible – otherwise State is Saved ). Making a VMHost “unavailable for placement” would also exclude the VMHost (eg: Offline Servicing Host) from the star rating used by the “intelligent placement”, but would leave the VMs running on it unharmed.
More information: http://blogs.technet.com/chengw/archive/2009/03/18/what-you-need-to-know-about-maintenance-mode.aspx

Some more VMM Frequently Asked Questions from TechNet

Find it here 

With courtesy of ServerTalk and Ben Armstrong for bringing it to our attention…