In the days before server virtualisation, it was mainly large enterprises that could afford a disaster recovery that entailed duplicating their entire server estate and having it sit around doing nothing.
All that changed with the arrival into the mainstream of server virtualisation, which eliminated the requirement that the secondary site be a hardware carbon copy of the primary one. A key benefit of virtualisation is its ability to save on disaster recovery infrastructure and that brings DR within the range of companies that were previously unable to afford it.
DR requires the restoration of an entire system quickly and easily, and virtualisation scores big here. Because a VM is independent of hardware, it’s easy to move or copy a server from one physical server to another server that you can recover from in case of disastrous events. Meanwhile, the falling cost of bandwidth means you can use remote offices as DR sites.
Even applications that do not run on virtual servers can be virtualised when replicated. If a mirrored virtual server runs at only 80 percent of the performance of the physical production machine, that’s still a lot better than complete service failure.
To further exploit the DR advantages of server virtualisation, hypervisor vendors are tailoring their products to DR requirements. VMware’s Site Recovery Manager, for example, offers features that support DR, such as planning, discovery and testing, and automated failover. Microsoft’s Hyper-V has fewer features aimed specifically at DR but can be successfully combined with products such as Vision Solutions’ Double-Take, which replicates servers and keeps them in sync. (VMware’s vSphere also supports such replication products.)
But there are wrinkles. You need to remember, for example, that in a Windows setup you’ll need to restore the domain controllers first or none of the services dependent on Active Directory, such as Microsoft Exchange, will work.
Designing and implementing a DR plan is a complex task, with variables that include technology, corporate policies, and available skill sets. Businesses are also starting to take advantage of cloud-based disaster recovery services, which is usually underpinned by server virtualisation too.
To investigate how UK companies are using server virtualisation, we talked with a London-based Hampden Group who is using Frontier Technology for its DR services.
Hampden Capital outsources Disaster Recovery
Hampden Capital delivers financial services to the Lloyds-backed insurance market. It is regulated by the Financial Services Authority (FSA) and follows the FSA’s best practices.
“If the best practices are to do ‘xyz,’ that’s what we do,” said Andrew Hough, IT manager. “This means we need to know how to be up and running within 30 to 60 minutes of a disaster.”
Hampden Capital discussed that requirement with Frontier Technology, its incumbent supplier for other IT services, and then subscribed to Frontier’s managed continuity solution. Frontier now mirrors all Hampden’s servers, both physical and virtual, to virtual machines on its premises.
“We told them which servers we wanted to cover, their sizes and how quickly we wanted them back working,” said Hough. “They manage it and test it once or twice a year, and we take part so we know it happened.”
The company employs about 150 people and houses its systems in its offices in the City of London. It has 10 physical servers–eight are in London, the rest are in an office in Buckinghamshire–and runs more than 20 virtual machines. Some servers remain unvirtualised, such as Exchange, file and print, the main SQL server, and Linux, but several Citrix servers, SUSE Linux, and miscellaneous application servers are virtualised.
When it came to DR, said Hough, “We wanted to cover Microsoft Exchange, SQL Server, the file and print servers, document management servers, and a Linux box.”
Before it bought into Frontier Technology’s services, Hampden had a limited DR plan. “In the event of a disaster, we would have had to rebuild from scratch using servers held off-site,” Hough said.
The impetus for a fresh look at how Hampden managed its DR came from the board, which mandated a “substantially quicker” DR process than had previously been in place. It previously took eight hours to restore email, and two days for the rest of the systems. The board rejected that as insufficient, prompting Hough to look for a managed service.
When it came to selecting a disaster recovery provider, one large telecom provider was rejected because of fears about the disparity between the sizes of the two companies. “We weren’t confident about the level of touchy-feely support they could offer,” said Hough. The other reject was a City-based IT provider that proffered a shopping list from which “they could probably do this or that,” Hough said. “We preferred that someone else do the trailblazing.”
The replication uses a VPN between Hampden’s and Frontier’s offices over a 50 Mbps leased line, and the DR plan is regularly tested. “Testing of the DR plan works on the basis that Frontier breaks the link on the synchronisation,” Hough said. The company has successfully conducted three tests in the last 18 months.
“The service sends text messages to us and Frontier in the event of any possible problem, and if we decide to switch over to the DR service, staff can then connect in via Citrix. Frontier provides an alternative public Web address to point to, so we can use Citrix services that we are all used to and it looks just the same,” Hough said.
“The text messages have been received very rarely and only when the power has gone down. We’re as confident as we can be that it works as it’s supposed to.”