Virtualisation strategies may cost more than many realise

More that 30% of both VMware and Microsoft virtualisation users have identified backing up VM data as problematic, while storage management, I/O bottlenecks and server availability monitoring can also be difficult with virtualisation. "With virtualisation you can automatically move virtual machines from one host to another and even from one data centre to another, so they'll stay up and running, with little or no downtime, in case of a failure," comments Mandeep Birdi, senior presales consultant at Diskeeper Says Corporation Europe. "[However], shared resources are of critical importance in a virtual environment, and are severely impacted by three key barriers: I/O bandwidth bottlenecks, due to accelerated fragmentation on virtual platforms; virtual machines competing for shared I/O resources and not effectively prioritised across the platform; and bloating – when virtual disks set to dynamically grow do not resize when data is deleted." Birdi points out that these problems can result in costing companies unnecessarily, in terms of additional hardware, as well as time in dealing with the issues. He also points to a recent survey by Diskeeper, which suggests that 25% of ITprofessionals are not dealing with the problems of I/O bottlenecks – with 5% indicating that they just purchase more disks/spindles. But Birdi finds that companies migrating to a virtualised environment, typically using a SAN (storage area network), are being told they don't need to defragment the SAN, and that there isn't an I/O bottleneck issue. "This is false, the I/O bottleneck issue can have a huge affect on performance, and if the customer is not aware that this is what's occurring in the SAN environment, it can again end up costing the company a lot of money with thinking they have to purchase more hardware, when in fact this might not be the case at all," he warns.