Xen, Hyper-V or ESX – how do they compare?
 For some, the question doesn't need to be asked. They're the people for whom VMware® ESX is the virtualisation benchmark, and will remain so for the foreseeable future. For them Microsoft Hyper-V is a non-choice, “ideal only if you don't really need virtualisation”, and deploying Xen or open source solutions is seen as taking unnecessary risks in a market where the sheer size of the two leaders means users can expect a certain degree of stability in their product offerings. And the somewhat confusing situation between Citirix and Microsoft® also needs to be taken into account.
And yet... as we discussed in a previous edition of ITRecovery News, there are good reasons – particularly the price – for enterprise customers who are starting to look closely at Hyper-V. And Citrix, with its Xen-based suite, offers an end-to-end solution which is exceptionally price competitive.
The news today – in December 2008 – is that all three solutions are functional; this wasn't the case six months ago. The two challengers have almost caught up with the leader where basic virtualisation features are concerned. A quick overview:
VMware Infrastructure 3.5. VMware, the market leader, has innovated continuously, year after year. Put simply, VMware delivers everything you need: performance, a wide range of features covering high availability, hot switching, support for all the leading storage solutions and interoperability with network infrastructure vendors, in particular Cisco. It would take too much space here to go into VMware's extensive partnership ecosystem. For large-scale, business-critical deployments, VMWare is the reference – but pricing remains an issue.
Microsoft Hyper-V: Released only three months ago, Hyper-V hasn't taken long to catch up with VMware, at least in so far as the key basic features are concerned. Performance has improved, apart from some minor I/O differences. As it's included in Windows Server® 2008 there's clearly a price advantage, though this remains open to debate for some. Hyper-V includes DPM and Multipath I/O for storage management, high availability, and the SCVMM management console, which supports VI3 and Hyper-V virtual machines. Hot switchover, however, is still missing, and there can be a delay when migrating virtual servers. Microsoft's solution can be summarised as less costly, with functionality integrated in a single product (Windows Server 2008), ideal for deployments that do not require the highest in high availability. Hyper-V may well beat out VMware in the typically more Windows-oriented SMB market.
Citrix XenServer™ Citrix acquired Xen Source®, a commercial release of the open source Xen solution, two years ago. With XenServer 5.0, Citrix has a full-featured competitive offering: hot switching (XenMotion™), high availability, improved support for storage infrastructures, easier disaster recovery planning, performance, and an improved management console (though certain features are still lacking). The next release of Workflow Studio is expected to fill the gaps in resource management. Citrix is best known for its application delivery technology, and in a certain sense, Citrix is tackling virtualisation back to front: customers will deploy Xen-based virtual servers once they've virtualised their applications.
The facts are that while server virtualisation can already be considered a mature technology, the next battleground is the desktop (or laptop) PC. VMware is once again taking the lead with its newly introduced VMware View, a next generation Virtual Desktop Infrastructure (or VDI). VMware View is a universal client incorporating VDI, ThinApp (application virtualisation) and View Composer (desktop system image management). But Microsoft and Citrix are not going to be left behind; App-V from Microsoft, and XenApp from Citrix, will be there to challenge VMware. The battle for the desktop has barely started. The key problem, yet to be solved, is the backup and restoration of virtual system images on the user's PC.
|
|
Should you chose a Hypervisor “lite”?
VMware and Microsoft both offer slimmed-down versions of their hypervisors taking up much less disk space – 32MB instead of 2GB for the VMware ESXi hypervisor). VMware achieves this by getting rid of the console. ESXi is a virtual machine based on a Linux micro-kernel, with privileged access to the VMFS file system and the hypervisor. Hyper-V takes much the same approach, removing Windows Server 2008. What are the benefits? Faster installation, faster booting, and improved security: the console service, the weakest link in hypervisor security is eliminated, dramatically reducing the vulnerability profile. And with it's reduced storage requirements, the hypervisor lite can be installed on a USB key or SSD storage. Certain vendors such as Dell, HP or IBM already include ESXi on their servers. But a hypervisor lite isn't the answer to every situation. The pure virtualisation features aren't an issue, but in large scale deployments the missing management tools will have an impact. VMware has developed a script-based management layer called CIM, accessible through WMI, but there are questions about the extent of interoperability with other vendors
|
|
