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Virtualisation may spell doom for the 1U "pizza box" server, as the ability to pack multiple virtual machines onto physical hosts has customers choosing larger standard servers and blades.

The iconic pizza box servers can't provide the VM density of blades, nor does it offer the levels of memory and CPU power found in larger 2U and 4U form factor servers, Nemertes Research analyst John Burke said during CIO UK sister title Network World's IT Roadmap conference.

That doesn't mean pizza box servers are being thrown by the wayside when it comes to workloads running on non-virtualised servers. But in IT shops that make extensive use of hypervisors, "the 1Us are losing," Burke said. "We expect that will continue."

Nemertes surveys show most customers will not repurpose old servers for virtualisation, instead buying new boxes that are more ideal for the partitioning technology. Blades, 2U and 4U servers "will almost completely replace the 1Us over the next few years" as hosts of VMs, he said.

Burke shared several other findings from Nemertes Research benchmark surveys of IT pros from a mix of small, medium and large enterprises. Ninety-three per cent of surveyed IT pros are already using virtualisation, though not necessarily in production.

Nearly four out of five have virtual servers hosting customer-facing applications, while on the whole 38 per cent of workloads are virtualised. About half the IT shops have seen quantifiable benefits from virtualisation.

Disaster recovery is one of the main benefits. After virtualising, 70 per cent of respondents can fail systems over in less than an hour, while 26 per cent can do so in five minutes. A third of respondents are able to fail over from a primary to a backup datacentre in less than an hour, while 10 per cent are able to do so in less than five minutes. Before virtualising, many small IT shops couldn't even afford a disaster-recovery site, and those that could were seeing failover times of two or three days, Burke said.

The findings were based on in-depth conversations, rather than written surveys. Some of the findings were based on a sample size of about 75 respondents, while other findings were based on a sample size of about 200, Burke said.

At first glance, virtualisation seems to improve manageability. On average, nine workloads are assigned to each administrator prior to virtualisation, while after virtualising more than 60 workloads can be handled by a single IT pro, Burke's research indicates.

But the management tools IT is accustomed to upon aren't designed for virtual systems, instead treating each server as a physical box hosting one application, he said.

"A lot of this is happening without robust support from the management tools they're used to relying on," Burke said. "There's this level of complexity being added back into the datacentre."

Virtualisation makes spinning up new applications seem so easy that many IT shops go overboard, until they learn their lesson.

"Virtualisation is like crack and people go crazy with it -- for a while," Burke said. Ultimately, datacentre managers learn to track life cycles and deploy VMs in a responsible manner.

One IT pro who spoke during the virtualisation track also used the "crack" analogy, saying that configuration errors contributed to a recent headache-filled day in which 10 or so VMs became inaccessible. Paul Lantieri, network operations manager for the Division of Health Care Finance and Policy in the Massachusetts state government, said his VMware environment and Dell/EqualLogic ISCSI storage-area network were having problems communicating with each other.

At one point, he discovered that the list of buffered commands that VMware has issued to the storage system was more than 12,000 long. Typically the number is less than five.

Ultimately, the government agency powered the entire datacentre down, after gaining assurances from vendors that they would not lose any critical data or workloads. To prevent future mishaps, Lantieri's team has changed the way it allocates resources, reduced the number of VMs connected to each data store, and are teaching developers how to write code for a virtual environment.

"Virtualisation is like crack sometimes," Lantieri said. "You do things in the virtual world that you probably shouldn't be doing. We were being too lenient and generous with our development groups."

Storage is often a sticking point when it comes to virtualisation, Burke said.

"A good number of the [IT pros we interviewed] had put virtualisation projects on hold for six months to a year to get their storage networking stories straightened out," Burke said. "They realized until they had networked storage that was virtualised appropriately they would not" achieve the benefits of virtualisation, such as site recovery.

Security is another potential problem, and one that too many IT pros have ignored, according to Burke. Network managers who routinely set up robust security for physical resources haven't done the same after virtualising, neglecting to set up virtual firewalls and security zones, Burke said. Even if this doesn't lead to security incidents, it could expose them to regulatory problems, he indicated.

"They were trading a level of assurance and auditability that they used to have for nothing," Burke said. "They could not show that they had not produced an unacceptable level of risk. Their security teams had not been paying close attention.