This document discusses best practices for configuring Hyper-V hosts and virtual machines. It recommends: - Using Server Core installation and dedicating hosts to the Hyper-V role for improved security and reliability. - Properly sizing host CPUs, memory, and storage and separating networks for management, storage, and VMs. - Configuring virtual machines with fixed VHDs, proper RAM and network settings, and latest integration components. - Implementing security practices like regular patching of VMs and limiting processor usage to prevent overcommitment. - Using VSS-aware backups and excluding unnecessary files/folders from antivirus scans to optimize performance.

1. Hyper-V Best Practices,
Tips and Tricks
Leon Shapritsky
Microsoft Regional Specialist
Malam-Team Ltd.

2. Host Configuration
Networking
Host Storage
Guest Storage
Guest Configuration
Security
Anti Virus / Backup

3. Host Configuration
Host CPUs (more are better)
Processor power is a major limiting factor
of how many VMs can be run on the host
Hyper-V R2 can use up to 64 logical
processors
You can scale up to 512 virtual processors
and/or 384 VMs

4. Host Configuration
If CPU doesn’t have SLAT, don’t buy it
Second Level Address Translation enabled
processors provide up to 25% improvement in
density
Intel calls it Extended Page Tables (EPT), AMD
calls it Nested Page Tables (NPT) or Rapid
Virtualization Indexing (RVI)
SLAT allows for pages of memory to be managed
at a hardware level
Significant improvement in memory management
and allows a significant scale increase over
previous processor architectures, especially for
memory-intensive workloads

5. Host Configuration
When you have servers with different CPU
architecture, use CPU compatibility mode
Enables migration of VMs between hosts
Use when performing
rolling hardware
upgrades of a cluster

6. Host Configuration
Host physical memory (more is better)
Host RAM is another major limiting factor of how
many VMs can be run on the host
At least 512 MB for the host itself
300 MB for the Hyper-V role
Sum of all the vRAM assigned for all VMs + 32
MB for the 1st GB of vRAM + 8 MB for each
additional GB of vRAM
Plan for expansion and for failover

7. Host Configuration
Choose the right OS SKU for virtualization
Windows Server 2008 R2 Datacenter Edition
– Flexible Virtualization Licensing
– Supports 2 TB RAM (Core or Full)
Hyper-V Server 2008 R2
– Lowest cost hypervisor (free)
– Supports 1TB RAM
– Supports Live Migration and
Failover Clustering

8. Host Configuration

9. Host Configuration
Use Server Core!
Windows Server frequently deployed for a single role,
especially true for Hyper-V servers
– Must deploy and service the entire OS in earlier Windows Server
releases
Server Core is minimal
installation option
– Provides essential server
functionality
– Command Line Interface
only, PowerShell, no GUI
Benefits
– Fundamentally improves
availability
– Less code results in fewer patches and reduced servicing burden
– Low surface area server for targeted roles
– More secure and reliable with less management, less human errors

10. Host Configuration
Networking
Host Storage
Guest Storage
Guest Configuration
Security
Anti Virus / Backup

11. Networking
Use separate logical networks
For storage, host management, virtual
machines, Live Migration

12. Networking
Chimney and RSS Settings Network Adapter level:
Chimney and RSS are configured in both
operating system and network adapter:
Operating System level:
Netsh int tcp show global
Netsh int tcp set global rss=enabled
chimney=enabled
http://technet.microsoft.com/en-us/library/gg162681(v=ws.10).aspx

13. Networking
Working with/without IPv6
– Do not unbind IPv6 from a single interface!
– The loopback interface keeps IPv6 even if you unselect it
from all NICs
– Be consistent in the entire enterprise (go either with, or
without)
– Disabling IPv6 may have an effect on various applications
such as HomeGroup, Remote Assistance, Direct Access
and others
– Windows 2008/7 was designed specifically with IPv6
present, Microsoft does not perform any testing to
determine the effects of disabling IPv6
How to disable certain Internet Protocol version 6 (IPv6)
components
http://support.microsoft.com/kb/929852

14. Networking
Use VMQ if the NIC supports it
– VMQ allows the physical NIC to
create unique virtual network
queues for each virtual machine
on the host, allowing network
packets to be passed directly
from the hypervisor to the VM.
– This reduces a lot of overhead
normally associated with network
traffic.
– If both Chimney and VMQ are
available on the same NIC at the
same time, Windows Server 2008
R2 will use VMQ.

15. Networking
Use Jumbo Frames
– Offers significant performance for TCP
connections including iSCSI
– Max frame size = 9K
– Reduces TCP/IP overhead by up to
84%
– Must be enabled at all end points
(switches, NICs, and target devices)
– Virtual switch is defined as an end
point
– Virtual NIC is defined as an end point
– Integration components required
– Benefits seen at 8K and above, the
higher the IO size the higher the
benefit of jumbo frames with 512K
request size seeing the best benefit

16. Networking
Use the same Virtual Switch names and Network
Interface names on all Hyper-V hosts
– Critical when migrating VMs between hosts
– Critical for Failover Clustering

17. Host Configuration
Networking
Host Storage
Guest Storage
Guest Configuration
Security
Anti Virus / Backup

18. Host Storage
When provisioning storage, request IOPS
More spindles = better performance
100 GB 100 GB 100 GB
200 GB
RAID 5
(200 GB)

19. Host Storage
Carefully monitor disk performance
Counters to watch in Performance Monitor snap-in:
– Avg. Disk Sec/Read
– Avg. Disk Sec/Write
Avg Disk second Read/Write (we want
to see .001 -.010 ideally for peak load)
Thresholds for the Operating System:
Under .010 (10 milliseconds) is Good
Over .015 (15 milliseconds), but under
025ms average is Acceptable to Poor
Over .025 (25 milliseconds) average is
Serious to Critical

20. Host Storage
Use CSV for better storage utilization

21. Host Configuration
Networking
Host Storage
Guest Storage
Guest Configuration
Security
Anti Virus / Backup

22. Guest Storage
Use Fixed size VHDs for better
performance
– Reduces VM Disk fragmentation (mainly for non-
SAN)
– Can’t be used in differencing disk scenarios
Although Hyper-V in R2 improved Dynamic
VHDs’ performance as much as 8 times when
compared to RTM, if possible, only use Dynamic
VHDs for lab, demo or testing purposes where
performance is not an issue.

23. Guest Storage
When creating a VM from SCVMM, it does
not add a SCSI adapter, you will need to
manually add it if you need it
SCSI vs. IDE in a VM doesn’t matter for
performance (when guest is enlightened/IC
installed)
SCSI adapters will let you connect up to 256 hard
disks to the VM
SCSI adapters allow to hot-add and hot-remove
virtual disks
System VHD must be attached to IDE virtual
controller

24. Guest Storage
Configure proper disk alignment
Needed when VHD was created in pre-Windows Server
2008, or when VM is running pre-Windows Server 2008
Diskpart > Select Disk <x> > List Partition
wmic partition get BlockSize, StartingOffset,
Name, Index
Msinfo32 Components > Storage > Disks

25. Guest Storage
http://gparted.sourceforge.net/
http://lifehacker.com/5837769/make-sure-
your-partitions-are-correctly-aligned-for-
optimal-solid-state-drive-performance
http://support.microsoft.com/kb/929491

26. Guest Storage
Format volumes with the right block size
Volume block size might vary (for example – SQL,
Exchange etc.)
wmic volume get blocksize, caption, label
fsutil fsinfo ntfsinfo
<drive letter>:

27. Guest Storage
Use native mount on host to perform AV
scans or backups of specific files
– Use Disk Management (UI) or Diskpart.exe
(CLI)

28. Guest Storage
Be familiar with snapshot
– Snapshots (also known as checkpoints in SCVMM)
are basically differencing disks (not related to VSS
snapshots)
– Merging/Deleting can take a considerable amount of
time

29. Host Configuration
Networking
Host Storage
Guest Storage
Guest Configuration
Security
Anti Virus / Backup

30. Guest Configuration
Use VM names that match the FQDNs of the
VM
– This is a must for VDI configuration and is also
considered a best practice for SCVMM and possibly
3rd-party tools

31. Guest Configuration
Make sure there is sufficient RAM
allocated to the VM
– Increased Disk I/O pagefile growth from disk
fragmentation (insufficient memory)
– Increased fragmentation requires memory
management
– Lack of memory grows the pagefile…
The amount of memory to assign will depend on
the workload of the VM, how much physical
memory is available on the host machine, and
how much memory other VMs running on the
same host machine are using.

32. Guest Configuration
Dynamic Memory
– Allows to set a startup and maximum RAM range for a
VM that supports it
– When VM starts, it uses the startup RAM amount, and
can be assigned more RAM based upon need (i.e.
Hot-Add memory)
– Additional memory allocation to the VM is subject to
priority assigned to the VM
http://technet.microsoft.com/en-us/library/ff817651(v=ws.10).aspx
Note that Dynamic Memory is NOT
overcommitting memory…

33. Guest Configuration
Dynamic Memory - Adding/Removing
Adding Memory
– Enlightened fashion
• Synthetic Memory Driver (VSP/VSC Pair)
– No hardware emulation
– Light weight
Removing Memory
– Memory Ballooning
• Confuses task manager in the guest OS

34. Guest Configuration
Dynamic Memory Requirements
Parent Requirements:
– Windows Server 2008 R2 SP1
– Microsoft Hyper-V Server 2008 R2 SP1
Guest Requirements:
– Windows Server 2003, 2008 & 2008 R2
• 32-bit & 64-bit versions You must install
– Windows Vista and Windows 7 the latest
Integration
• Enterprise and Ultimate Editions only Components!
• 32-bit & 64-bit versions

35. Demo

36. Guest Configuration
Use Integration
Components for best
performance on VM
IC are built-in into
Windows Server
2008/R2/Vista/7
When migrating a VM
from Hyper-V RTM to R2,
make sure you update the
IC on the guest.
IC are required for VSS
backups.
Also available for Linux
versions (supporting SMP)

37. Guest Configuration
Enable support for time synchronization
If any VM on a host belongs to a domain but the
host itself does not, ensure that the host
synchronizes with the
same time source used
by the domain to
eliminate synchronization
conflicts between the host
and domain.
Client < DC < PDC Emulator < External time source

38. Guest Configuration
When creating a VM with SCVMM, make sure you
use an Syntetic NIC
Otherwise, you will have network performance issues

39. Guest Configuration
Configure automatic Start Action
Enables VM to automatically start when host was
rebooted
Stagger automatic booting
in order to properly load
dependency services or
applications

40. Host Configuration
Networking
Host Storage
Guest Storage
Guest Configuration
Security
Anti Virus / Backup

41. Security
Treat VMs just like physical servers
Harden each virtual machine according to the server
roles it performs.
Perform routine Windows Updates, just like on
regular hosts
– Many VMs are often kept offline for long periods of time.
– If deployed and started, the out-of-date virtual machine
might be vulnerable to attack or could be capable of
attacking other network resources. (Conficer)
Consider using the Offline Virtual Machine Servicing Tool
http://www.microsoft.com/downloads/details.aspx?FamilyId=8408ECF5-
7AFE-47EC-A697-EB433027DF73&displaylang=en

42. Security
Impose limits on processor usage
By default, each VM is allowed to use 100% of the
processing power of a single processor core.
A compromised VM that can use all of the processing
power on the host machine could cause the host
machine and other VMs
running on it to become
unresponsive.

43. Host Configuration
Networking
Host Storage
Guest Storage
Guest Configuration
Security
Anti Virus / Backup

44. Anti-Virus / Backup
– Exclude directories, files and processes from
AV scan http://support.microsoft.com/kb/961804
– Default virtual machine configuration directory
(C:ProgramDataMicrosoftWindowsHyper-V)
– Custom virtual machine configuration directories
– Default virtual hard disk drive directory
(C:UsersPublicDocumentsHyper-VVirtual Hard Disks)
– Custom virtual hard disk drive directories
– Snapshot directories
– Vmms.exe and Vmwp.exe
– Additionally, when you use Live Migration together with
Cluster Shared Volumes on Windows Server 2008 R2,
exclude the CSV path "C:Clusterstorage" and all its
subdirectories.
– http://support.microsoft.com/kb/822158

45. Anti-Virus / Backup
Stagger AV scans schedule
– If all of the VMs are scanned at 2 AM, then
the entire system may come to a crawl until
the scan is complete.

46. Anti-Virus / Backup
Use VSS aware backup to backup entire VMs
When using Pass-Through disks for VMs, be aware that
VSS-based backups will not back these drives
Make sure IC are installed and enabled for backups
If VSS backup cannot be performed, the VM will be
paused temporarily

47. Types of VM Backups
Three types of Backups:
– Backing up the host system
• May be necessary to maintain host configuration
• But often, not completely necessary
• The fastest fix for a broken host is often a complete rebuild
– Backing up Virtual Disk Files
• Fast and can be done from a single host-based backup client
• Challenging to do file-level restore
– Backing up VM’s from inside the VM
• Slower and requires backup clients in every VM.
• Resource intensive on host
• Capable of doing file-level restores

48. Useful Commands
Wmic nic get netconnectionid,speed
Wmic volume get caption,blocksize,label
wmic service where "State='Running'" get caption
wmic volume where "Caption='C:'" get Label
wmic volume where "Caption='C:'" set Label=System
wmic pagefileset where name="c:pagefile.sys" delete
wmic.exe pagefileset create name="C:pagefile.sys"
sc config msiscsi start= auto
Features/Roles:
– Import-Module Servermanager
– Get-WindowsFeature
– Add-WindowsFeature <name> -restart
– Add-WindowsFeature <name1>, <name2>, <name3>
Teaming:
– BROADCOM: C:Program FilesBroadcomBACS>BACS.exe
– INTEL: C:Program FilesIntelDMIXCL>PROSetCL.exe prosetcl.exe
Team_Create 1,2 VMs VMLB

49. Virtualization is constantly evolving
New technologies = New best practices
Use common sense
Questions?