It's a norm now; over the last couple of years, whenever there has been a discussion over the features of Hyper-V, experts and admins have pitted it against the other two leading competitors, though the focus used to be primarily on VMware. From being mocked at to becoming a serious competitor and now almost at par, the Hyper-V development team has pulled the reins strongly to catch up with VMware's ESXi. The community, which was once split in their opinion, is now adopting and becoming aware of both hypervisors, with experts from the other side honing their skills on Hyper-V. The rise of Hyper-V, in a way, can be attributed to VMware for their vision of server virtualization. The next notable contender in the list of hypervisors is Citrix's XenServer, which went fully open source last year, with its XS 6.2 release. There are similarities, yet there are differences between the products, both from the architecture and feature standpoints. Let's look at some of those striking features stacked together.
The following table depicts the hypervisor's host attributes and configuration limits. These are considered as guidelines for setting up a virtual data center:
|
Microsoft Windows Server 2012 R2 / System Center 2012 R2 Datacenter Edition |
VMware vSphere 5.5 Enterprise Plus with operations management / vCenter Server 5.5 |
Citrix XenServer 6.2 Single Product Edition / XenCenter 6.2 management console | |
|---|---|---|---|
|
Hypervisor type and footprint |
|
|
|
|
Maximum memory (per host) |
4 TB |
4 TB |
1 TB |
|
Maximum number of processors (per host) |
320 (logical) |
320 (logical) |
160 (logical) |
|
Maximum number of active VMs / consolidation (per host) |
1,024 VMs |
512 VMs |
450 VMs (Windows) 650 VMs (paravirtualized and Linux-based) |
|
Maximum number of virtual CPUs (per VM) |
64 |
64 |
16 |
|
Hot-adding virtual CPU to VM |
Partial support by allowing alterations to virtual machine limits |
Supported (limitations from VOSE and VMware FT) |
Not supported |
|
Maximum virtual RAM (per VM) |
1 TB |
1 TB |
128 GB |
|
Hot-adding virtual RAM to VM |
Supported (via dynamic memory) |
Supported |
Not supported |
|
Dynamic memory management |
Supported (via dynamic memory ) |
Supported (via memory ballooning and transparent page sharing) |
Supported (via dynamic memory control, or DMC) |
|
Virtual NUMA support for VMs |
Supported |
Supported |
Not supported |
|
Maximum number of physical hosts per cluster |
64 nodes |
32 nodes |
16 nodes |
|
Maximum number of VMs per cluster |
8,000 VMs |
4,000 VMs |
800 VMs |
|
VM snapshots |
Supported—support for 50 snapshots per VM |
Supported—support for 32 snapshots per VM, (VMware, as best practice, recommends two to three snapshots.) If VMs are using an iSCSI initiator |
Supported—support for one snapshot per VM |
|
Bare-metal/automated host deployment |
Supported (System Center 2012 R2 Virtual Machine Manager) |
Supported (VMware's auto-deploy and host profiles make it possible to perform bare-metal deployment of new hosts on a pre-existing cluster. However, it will not perform bare-metal deployment of new clusters.) |
Supported (no integrated deployment application however possible via unattended installation over from a network repository) |
|
GPU advancements |
Supported via RemoteFX and VDI features in the RDS role |
Supported via vDGA and vSGA features |
Supported via HDX and vGPU (Kepler Architecture K1/K2) features |
|
Boot from SAN |
Supported via the iSCSI target server or third-party iSCSI / FC storage arrays |
Supported via third-party iSCSI/FC storage arrays |
Supported via third-party iSCSI / FC storage arrays |
|
Boot from USB/Flash |
Supported |
Supported |
Not supported |
The following table shows comprehensively how each hypervisor supports various operating system platforms as virtualized workloads:
Note
For the most recent and complete list of supported operating systems, please refer to these links:
Microsoft: Supported server and client guest operating systems on Hyper-V; http://technet.microsoft.com/library/hh831531.aspx
VMware: A compatibility guide for guest operating systems supported on VMware vSphere; http://www.vmware.com/resources/compatibility
Citrix: XenServer 6.2.0 Virtual Machine User's Guide; http://support.citrix.com/article/CTX137830
|
Microsoft Windows Server 2012 R2 / System Center 2012 R2 Datacenter Edition |
VMware vSphere 5.5 Enterprise Plus / vCenter Server 5.5 Standard Edition |
Citrix XenServer 6.2 Single Product Edition / XenCenter 6.2 | |
|---|---|---|---|
|
CentOS 5.5-5.6, 5.7-5.8, 5.9, 6.0-6.3, and 6.4 - 6.5 |
Supported |
Supported |
Supported |
|
CentOS Desktop 5.5-5.6, 5.7-5.8, 5.9, 6.0-6.3, and 6.4 - 6.5 |
Supported |
Supported |
Supported |
|
Oracle Linux 6.4 and 6.5 with UEK |
Supported (Oracle certified) |
Supported (Oracle has not certified any of its products to run on VMware) |
Supported |
|
Mac OS X 10.7.x and 10.8.x |
Not supported |
Supported |
Not supported |
|
Red Hat Enterprise Linux 5.5-5.6, 5.7-5.8, 5.9, 6.0-6.3, and 6.4 - 6.5 |
Supported |
Supported |
Supported |
|
Red Hat Enterprise Linux Desktop 5.5-5.6, 5.7-5.8, 5.9, 6.0-6.3, and 6.4 - 6.5 |
Supported |
Supported |
Supported |
|
SUSE Linux Enterprise Server 11 SP2 and SP3 |
Supported |
Supported |
Supported |
|
SUSE Linux Enterprise Desktop 11 SP2 and SP3 |
Supported |
Supported |
Supported |
|
OpenSUSE 12.3 |
Supported |
Supported |
Supported |
|
Sun Solaris 10 and 11 |
Not supported |
Supported (Oracle has not certified any of its products to run on VMware) |
Not supported |
|
Ubuntu 12.04, 12.10, 13.04, and 13.10 |
Supported |
Supported |
Supported |
|
Ubuntu Desktop 12.04, 12.10, 13.04, and 13.10 |
Supported |
Supported |
Supported |
|
Windows Server 2012 R2 |
Supported |
Supported |
Supported (with SP1) |
|
Windows 8.1 |
Supported |
Supported |
Supported (with SP1) |
|
Windows Server 2012 |
Supported |
Supported |
Supported |
|
Windows 8 |
Supported |
Supported |
Supported |
|
Windows Server 2008 R2 SP1 |
Supported |
Supported |
Supported |
|
Windows Server 2008 R2 |
Supported |
Supported |
Supported |
|
Windows 7 with SP1 |
Supported |
Supported |
Supported |
|
Windows 7 |
Supported |
Supported |
Supported |
|
Windows Server 2008 SP2 |
Supported |
Supported |
Supported |
|
Windows Home Server 2011 |
Supported |
Not supported |
Supported |
|
Windows Small Business Server 2011 |
Supported |
Not supported |
Supported |
|
Windows Vista with SP2 |
Supported |
Supported |
Supported |
|
Windows Server 2003 R2 SP2 |
Supported |
Supported |
Supported |
|
Windows Server 2003 SP2 |
Supported |
Supported |
Supported |
|
Windows XP with SP3 |
Supported |
Supported |
Supported |
|
Windows XP x64 with SP2 |
Supported |
Supported |
Supported |
The following table depicts various storage-related features, from both the host and the VM perspective, promoted by each hypervisor platform:
|
Microsoft Windows Server 2012 R2/System Center 2012 R2 Datacenter Edition |
VMware vSphere 5.5 Enterprise Plus / vCenter Server 5.5 Standard Edition |
Citrix XenServer 6.2 Single Product Edition / XenCenter 6.2 Management Console | |
|---|---|---|---|
|
Maximum number of SCSI virtual disks per VM |
256 |
60 (PVSCSI disks) and 120 (Virtual SATA disks) |
16 (VDI via VBD) |
|
Maximum size per virtual disk |
64 TB (VHDX) and 2 TB (VHD) |
62 TB |
2 TB |
|
4K Native (4K logical sector size) disk support |
Supported |
Not supported |
Not supported |
|
Boot VM from SCSI virtual disks |
Supported (generation 2 VMs onwards ) |
Supported |
Supported |
|
Hot-adding virtual SCSI (running VMs) |
Supported |
Supported |
Supported |
|
Hot-extending virtual SCSI (running VMs) |
Supported |
Supported (except 62 TB VMDKs) |
Supported (via XenConvert) |
|
Hot-shrink virtual SCSI (running VMs) |
Supported |
Not supported |
Supported (via XenConvert) |
|
Storage migration (running VMs) |
Supported, with unlimited number of simultaneous live storage migrations. Provides flexibility to cap at a maximum limit that is appropriate as per for your datacenter limitations. |
Supported, with two simultaneous storage vMotion operations per ESXi host. Alternatively, there can be eight simultaneous storage vMotion operations per data store. Also, the feature cannot be extended to VM Guest Clusters with MSCS |
Supported, with three simultaneous storage Xenmotion with a cap of one snapshot per VM undergoing migration |
|
Virtual FC to VMs |
Supported (four Virtual FC NPIV ports per VM) |
Supported (four virtual FC NPIV ports per VM). However, the feature cannot be extended to VM guest clusters with MSCS. |
Not supported |
|
Storage quality of service |
Supported (storage QoS) |
Supported (storage IO control) |
Supported (I/O priority on virtual disks) |
|
Flash-based read cache |
Supported |
Supported |
Not supported |
|
Flash-based write-back cache |
Supported—Storage Spaces |
Supported—Virtual SAN |
Not supported |
|
Storage virtualization abilities |
Supported—Storage Spaces |
Supported—Virtual SAN |
Not supported |
|
Deduplication of shared storage hosting VMs |
Supported (VDI workloads) |
Not supported |
Not supported |
This table mentions the networking features provided by each hypervisor model, which can help architects design their environments:
|
Microsoft Windows Server 2012 R2 / System Center 2012 R2 Datacenter Edition |
VMware vSphere 5.5 Enterprise Plus / vCenter Server 5.5 Standard Edition |
Citrix XenServer 6.2 Single Product Edition / XenCenter 6.2 Management console | |
|---|---|---|---|
|
Distributed switch |
Logical switch in System Center VMM 2012 R2 |
vDS (vNetwork distributed switch) |
Open vSwitch (the distributed vSwitch is deprecated) |
|
Extensible virtual switch |
Supported. Extensions are offered by Cisco, Inmon, and 5nine |
Replaceable, and not truly extensible |
Supported via Open vSwitch |
|
NIC teaming |
Supported. Thirty-two NICs per team utilize dynamic load balancing |
Supported. Thirty-two NICs per team utilize the Link Aggregation Group |
Supported. Four NICs per bond utilize the Link Aggregation Group |
|
PVLANs (private VLANs) |
Supported |
Supported |
Supported |
|
ARP spoofing security |
Supported |
Supported, via an additional paid add-on vCloud Network and security (vCNS) or vCloud suite |
Supported |
|
DHCP snooping security |
Supported |
Supported, via an additional paid add-on vCloud Network and security (vCNS) or vCloud suite |
Not supported |
|
Router Advertisement (RA) guard protection |
Supported |
Supported, via an additional paid add-on vCloud network and security (vCNS) or vCloud suite |
Not supported |
|
Virtual port ACLs |
Built-in support for extended ACLs |
Supported, via traffic filtering and marking policies in vSphere 5.5 vDS |
Supported |
|
Software-defined Networking (SDN) / network virtualization |
Supported (the NVGRE protocol) |
Supported, via an additional paid add-on VMware NSX |
Supported, via paid add-on Cloud Platform SDN Controller and SDN plugins |
The final table depicts the high availability and mobility offerings by each hypervisor platform:
|
Microsoft Windows Server 2012 R2/System Center 2012 R2 Datacenter Editions |
VMware vSphere 5.5 Enterprise Plus/ vCenter Server 5.5 Standard Editions |
Citrix XenServer 6.2 Single Product Edition/XenCenter 6.2 Management console | |
|---|---|---|---|
|
Live migration (running VMs) |
Supported. There can be unlimited simultaneous live VM migrations, depending on the data center's capacity |
Supported, but limited to four simultaneous vMotions for 1GbE and eight simultaneous vMotions for 10 GbE network adapters |
Supported, but one at a time, and in a sequence |
|
Live migration (running VMs without shared storage) |
Supported |
Supported |
Supported |
|
Live migration enabling compression of VM state |
Supported |
Not supported |
Not supported |
|
Live migration over RDMA network adapters |
Supported |
Not supported |
Not supported |
|
VM guest cluster (Windows Failover Clustering) live migration |
Supported |
Not Supported, as per the vSphere MSCS setup documentation |
Not supported |
|
Highly available (HA) VMs |
Supported |
Supported |
Supported |
|
Affinity rules for HA VMs |
Supported |
Supported |
Not supported (workload balancing is a retired feature) |
|
Orchestrated updating of hypervisor hosts. |
The Cluster-aware Updating (CAU) role service |
vSphere 5.5 Update Manager, with additional costs |
XenCenter Management with additional license costs |
|
Application monitoring and management for HA VMs |
System Center 2012 R2 Operations Manager |
VM Monitoring Service and vSphere App HA |
Not supported |
|
VM guest clustering (shared virtual hard disk) |
Shared VHDX |
Shared VMDK |
Not supported (Shared VDI) |
|
Maximum number of nodes in a VM guest cluster |
64 VM nodes |
5 VM nodes |
Not supported |
|
Fault-tolerant (Lockstep) VMs |
Not supported. As per Microsoft, application availability can be well managed via highly available VMs and VM guest clustering, which is more economical and easier to manage. In the case of stringent requirements, fault-tolerant hardware solutions can be opted for |
VMware FT |
Not supported |
This table lists a subset of feature considerations to bring to your attention how well the aforementioned products placed against are each other, with Hyper-V edging out VMware and Citrix in the race with its recent release. In later chapters, we will look at some of the these features closely.