Windows Server 2008 Hyper-V, hypervisor-based server virtualization technology, allows you to make the best use of your server hardware investments by consolidating multiple server worklaods as separate virtual machines (VMs) running on a single physical machine. With Hyper-V, you can also efficiently run multiple different operating systems concurrently, on a single server, and fully leverage the power of x64 computing.
When you’re planning a virtualization infrastructure with Hyper-V, please be sure to stay within the supported limits below. In addition, the limits discussed in this document are highly dependent on the underlying hardware server configuration.
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Operating System Requirements
Windows Server 2008 includes Hyper-V as an available role. Hyper-V is included with:
- Windows Server 2008 Standard Edition (x64)
- Windows Server 2008 Enterprise Edition (x64)
- Windows Server 2008 Datacenter Edition (x64)
Note: That Hyper-V is an x64 Edition only technology and is not available for 32-bit (x86) or Itanium (IA64) editions.
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Hardware Requirements
- Hyper-V requires an x64 processor with Hardware-assisted virtualization. This is available in processors that include a virtualization option; specifically, Intel VT or AMD Virtualization.
- Hardware Data Execution Protection (DEP) is also required and must be enabled. Specifically, you must enable Intel XD bit (execute disable bit) or AMD NX bit (no execute bit).
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Virtual Machine Architecture Support
- Hyper-V offers support for:
- 32-bit (x86) operating systems
- 64-bit (x64) operating systems
Both 32-bit and 64-bit virtual machines can run concurrently.
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Memory:
- Windows Server 2008 Enterprise/Datacenter Editions
- System/Host Physical memory support: Up to 1 TB of physical memory
- Virtual Machine memory support: Up to 64 GB of memory per virtual machine
- Windows Server 2008 Standard Edition
- System/Host Physical memory: Up to 32 GB of physical memory
- Virtual machine memory support: Approximately ~31.5 GB total used for all running virtual machines
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Processors:
- Physical Processor support: Hyper-V is supported on systems with up to 16 logical processors; A logical processor can be a core or a hyper-thread. Examples include:
- Single processor/Dual core system = 2 logical processors
- Single processor/Quad core system = 4 logical processors
- Dual processor/Dual core system= 4 logical processors
- Dual processor/Quad core system=8 logical processors
- Quad processor/Dual core system= 8 logical processors
- Quad processor/Dual core, hyper-threaded systems=16 logical processors
- Quad processor/Quad core systems=16 logical processors
- Virtual Processor support: Up to 4 virtual processors per virtual machine
Note: Hyper-V may run on systems with greater than 16 logical processors; however these configurations are not supported.
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Networking:
- Up to 12 virtual network adapters per virtual machine
- 8 synthetic network adapters
- 4 emulated network adapters
- Each virtual network adapter can use either a static or dynamic MAC address
- Each virtual network adapter offers integrated VLAN support and can be assigned a unique VLAN channel
- Unlimited number of virtual switches with an unlimited number of virtual machines per switch
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Physical Storage:
- Hyper-V offers flexible storage support such as:
- Direct Attach Storage (DAS): SATA, eSATA, PATA, SAS, SCSI, USB, FIrewire
- Storage Area Networks (SANs): iSCSI, Fiber Channel, SAS
- Network Attached Storage (NAS)
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Virtual Hard Disks:
- Dynamically Expanding Virtual Hard Disks:
- Default type maximum size up to 2040 GB each
- Fixed Size Virtual Hard Disks:
- Maximum size up to 2040 GB each
- Pass-through disks
- No size limitation other than what is supported by the guest operating system
Virtual Storage Controllers:
- Virtual IDE
- Each virtual machine supports up to 4 IDE devices
- One IDE device must be a virtual disk (VHD or pass-through) for boot
- Virtual SCSI
- Each virtual machine supports up to 4 virtual SCSI controllers
- Each controller supports up to 64 disks for a total of 256 virtual SCSI disks PER virtual machine.
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Virtual Storage:
- Total storage per virtual machine:
- Using virtual hard disks, each virtual machine supports 512 TB of storage per VM
- Using pass-through disks, this number is even greater depending on what is supported by the guest operating system;
- Virtual Machine Snapshots:
- Hyper-V supports up to 50 snapshots per virtual machine
- Virtual Machine Boot
- Virtual machines must boot from a virtual IDE device; however, that device can be backed by a wide array of storage options including:
- Direct Attach Storage (DAS): SATA, eSATA, PATA, SAS, SCSI, USB, FIrewire
- Storage Area Networks (SANs): iSCSI, Fiber Channel, SAS
- Network Attached Storage (NAS)
IMPORTANT: Although the I/O performance of physical SCSI and IDE can differ significantly, this is not true for the virtualized SCSI and IDE devices in Hyper-V. Hyper-V IDE and SCSI storage devices both offer equally fast high I/O performance when integration services are installed in the guest operating system.
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Virtual CD/DVD:
- Maximum number of virtual CD/DVDs: By default, each virtual machine is provided one virtual CD/DVD. However, each virtual machine can support up to 3 virtual DVD drives per virtual machine (on the virtual IDE bus only) as one IDE device must be used as a virtual boot device.
- Pass-through CD-DVD:
- For security purposes, only one virtual machine can access a physical CD/DVD at a time.
- Virtual CD/DVD:
- Hyper-V supports reading virtual CD/DVD .ISO files
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Virtual Serial (COM) Ports
Each virtual machine supports up to 2 virtualized COM ports that can be used to communicate with a physical server (local or remote) via a serial named pipe.
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Virtual Floppy Drive
- Each virtual machine supports up to 1 virtual floppy drive
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Number of Virtual Machines:
- Supports up to 128 concurrent running virtual machines
- Supports up to 512 configured virtual machines
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