Slimming down storage

When the IT team at the London Borough of Hillingdon embarked on its first server virtualisation project back in 2006, it did not make that move out of choice. “Our hand was forced,” admits Roger Bearpark, the council’s head of ICT. “We had literally no more room in the data centre and our energy supplier couldn’t provide us with any more power.”

That does not sound like a very promising start. However, the Hillingdon team found the benefits of its early virtualisation efforts so compelling that they rapidly started to broaden the scope of their ambitions.

But that soon raised questions about the state of the council’s existing storage area network (SAN). “We were conscious that if we didn’t have the right storage environment to go with our virtualised servers, we might really struggle with providing virtual machines with the storage they need to run. We would certainly run the risk of losing control over the storage environment,” says Bearpark. The easy route, he adds, would have been to “keep buying additional disk, month in, month out”.

Instead, the Hillingdon team decided on a different approach. In 2008, it implemented two new tiered SANs, with thin provisioning technology, from Compellent. One was installed at the council’s main site and one five miles away as part of its business continuity strategy.

Storage tiering has offered some dramatic performance improvements, says Bearpark. The council’s previous SAN could not automatically distinguish between primary and secondary data, meaning that the IT team had to choose between manually moving secondary data to less expensive media or leaving it on expensive, high-speed disks.

The Compellent SAN, however, recognises infrequently accessed data and automatically moves it from high-performance Fibre Channel disks (Tier One) to less expensive, high-capacity SATA storage (Tier Two).

Last year, says Bearpark, his team added super-fast solid-state disks (SSD) to the mix (Tier Zero) in order to improve performance for the council’s contact centre. “We invested in a relatively small amount of SSD – just for the most accessed parts of the contact centre’s underlying Oracle database – but we are achieving I/O speeds of up to 13 times faster as a result,” he says.

Thin provisioning, meanwhile, has eliminated the allocated but unused capacity that existed in its previous SAN. This has meant that Hillingdon has been able to purchase less storage hardware upfront and to defer storage upgrades. “It also saves on floor space and on electricity costs, too – truly green storage,” says Hillingdon.

And although Hillingdon is storing more data than ever before, Bearpark and his team are paying 70% less to manage one terabyte over three years than they were back in 2004.

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