June 26, 2009 Leave a comment
I’ve been using virtualisation since the early days and can firmly remember running the MS Virtual Server 2005 Alpha builds on my production development hosts back in 2004. My company was only about 15 people at the time and every piece of hardware was a precious resource (naturally this is still the case!), so the ability to run lots of development environments on each was just too much to resist.
As the company expanded so did our virtualisation needs and a couple of years ago we purchased a shiny fibre channel Dell CX3 SAN along with 6 VMWare ESX 3.0 hosts. One of the major selling points of this was Live Migration, the ability to migrate a virtual machine from one physical host to another with no perceived downtime to the end user. Live Migration is a wonderful thing but it does have rather demanding hardware requirements in the form of shared storage, which can often put it out of reach of the majority of IT departments before they even start looking at the substantial cost of ESX licences.
Fast forward to today and things have changed somewhat, there are multiple vendors offering live migration and the pricing has shifted away from the hypervisor itself to the management solutions. As a result each vendor offers a free edition of their hypervisor with a cut down feature set:
VMWare has ESXi, basically just a bare metal hypervisor, it comes with VMWare’s over-commit memory management which is nice, but that’s about it. It is capable of centralised management and live migration – but to activate those features you need to apply a full licence to it… which removes the “Free” aspect of the product.
Microsoft’s latest free offering “HyperV Server2008 R2”, brings some interesting features to the table which I don’t think have been adequately publicised. In addition to the standard hypervisor features from the previous version, the R2 edition comes with failover clustering, including Live Migration! Suddenly Enterprise level virtualisation features are within the grasp of every IT department without needing to blow the budget. It is also possible to have centralised management via SCVMM 2008 R2 (like VMWare this requires a licence), but this is not a requirement for any of the features. For the purposes of this environment I have just been using the standard Server 2008 remote administration tools.
Of course the software is only half the battle as if you don’t have shared storage you’re still out of luck. A quick chat to my Dell account manager and a quote dropped into my mailbox for a entry level iSCSI SAN with about 8TB storage (RAID5), redundant power supplies,data paths, etc. Its a nice cheap solution and a bit of negotiation soon got it down to the <5k mark, but assuming you can live without redundancy and are not looking for performance then there is a cheaper option. Grab a desktop PC or old server, install a software iSCSI target, throw some high capacity cheap disks in it and you’ve got yourself a cheap SAN that is capable of serving Live Migration hosts. Its not pretty and won’t impress anyone with its performance, but it does the job.
Over the past few days I have built a test setup out of some spare hardware. It is essentially 4 HyperV Server2008 R2 hosts and a software SAN providing the shared storage. So far its working very well.
I’ll post back with how it was setup, what software/configurations are being used and any problems shortly…