Body: If you’ve virtualised and consolidated your servers, you may well be looking at a spreadsheet, counting your return on investment and deciding you can put your feet up for a deserved reward.
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Not so fast. Your newly notional collection of computing power brings with it some interesting issues, not the least of which is security.
Security is an issue because virtual machines do something their physical cousins seldom contemplate: they go offline for protracted periods of time. This can create security issues because a server that operates 24x7 will automatically download any operating system or application patches. If you don’t allow automated downloads, it’s probably because you have a patch management system in place to apply fixes in a more orderly fashion.
Whatever your patching regime, it’s important to ensure it applies to dormant virtual machines, lest they wake in an un-patched state and fall victim to attacks that seek out unprotected machines.
It’s therefore critical to deploy tools that apply patches to virtual machines before they are awakened.
Another virtual security angle to consider is the security of a host or cloud provider you use to house virtual machines. It’s important to do so because virtual machines you rent from such providers could be on the same physical server as several others.
The security community is increasingly fond of pointing out that a data centre full of virtual machines is a very tempting target for a criminal thanks to the sheer volume of targets on offer. Advisors also point out that they may be an easy target, as one compromised virtual machine could become a gateway to breaching the defences of others in the same facility.
It is therefore critical to have a long, hard, talk about a hosting or cloud provider’s security provisions, especially with regard to the precautions it has in place to protect multi-tenancy environments.
It’s easy enough to backup a virtual machine and the data it creates, but doing so well requires attention to some fine details that enable faster restores.
Those details principally concern the many files an operating system spawns when it installs. Of course it is not hard to re-install an operating system, but when you are recovering from a severe incident the last thing you want to do is recreate a server. Dedicated virtual machine backup tools therefore capture all the finicky little bits of an OS in a form that means you can restore a virtual machine without the need for a rebuild.
Virtual machine creation rights
One of the lovely things about virtualisation is that you can create a new server in just a few minutes, instead of waiting for a server to be built, delivered and configured.
Business people rave about this flexibility, but the flipside of their enthusiasm and the speed afforded by virtualisation is risk that your team will create too many virtual machines.
The rest is known as “VM sprawl” and creates a challenge as organisations find themselves with servers galore. Large fleets of virtual servers need as much management attention as physical servers, and each new virtual machine will consume storage resources and need to be backed up. Letting anyone in your organisation create a virtual machine is not a great idea.
Restricting the right to create virtual machines is therefore an idea many virtualisation users have implemented.
It’s also worth thinking about end-users’ ability to hire virtual machines from external providers. Many organisations now offer the chance to rent a virtual machine that ‘lives’ in the cloud, and TechTarget ANZ has reported on one organisation where business people now compare the speed and cost of such servers from external providers and it’s own IT department’s price for the same service. Others have speculated that business units could rent virtual machines from clod providers without IT departments ever knowing of their existence, a compliance concern as this scenario results in corporate data leaving the firewall and departing for an unknown environment.
As it is possible to rent a virtual machine with a credit card it’s not easy to prevent staff from choosing this route, leaving policy as the most likely way to prevent the proliferation of virtual machines outside an organisation.
Software licensing for virtual machines
Software vendors have not always been enthusiastic about virtualisation, because it challenges some of their favourite pay-per-processor business models. Some have devised ever-more complex licenses that permit more virtualisation, but tie CIOs’ heads in knots figuring out just what they mean.
Virtualisation vendors aren’t much better.
When building virtualised infrastructure it therefore pays to develop a very, very, clear understanding of the licenses on offer, lest you find yourself on the wrong end of a nasty letter or license audit from a vendor or intervention by the Business Software Association of Australia.
One of the popular emerging uses for virtualisation is replacing conventional PCs with desktops that load operating systems stored as virtual machines on a storage area network. Known as virtual desktop infrastructure (VDI), this approach is an attempt to address the high cost of ownership that comes with desktop computers.
Some users of VDI have, however, encountered some problems because most users of desktop computers work nine to five and most log on during an hour or so in the morning. When those workers’ computers switch on, they all access the storage area network (SAN) to download their operating system. They also quickly seek out the Internet in order to check if any new antivirus signatures or operating system patches need to be downloaded.
In larger organisations, the result of so many computers performing the same tasks in a short time can create what has been termed an “input/ouput storm” that stresses SANs, local area networks and internet connections to their limits.
Newer VDI tools are now engineered to ameliorate input/ouput storms, but it still behoves virtualisation users to ensure that their VDI deployments – and fleets of virtual servers that may also create storms – are configured in ways that reduce the severity of storms.