Business college gets Nimble hybrid flash to replace LeftHand SAN

Ashridge Business School dumped creaking end-of-life LeftHand array for Nimble Storage hybrid flash array in a move that also saw Nexenta storage software rejected

A Hertfordshire business college has upgraded to a Nimble Storage hybrid flash array to replace a struggling Lefthand Networks SAN that had reached end of life. During evaluation it ran a proof-of-concept on Nexenta storage software but that did not pass muster for the college’s needs.

Ashridge Business School is an executive learning establishment that runs courses, conferences and events. It has 400 staff and sees 6,000 students pass through its doors annually for a total of 450 workstation seats.

Core applications include email, home-grown CRM and ERP apps, financials and web serving. All of these were delivered from a LeftHand Networks NSM 2120 SAN with an HP expansion module.

The college has been through a process of virtualising servers and had gone from 80 physical devices to five running 72 virtual machines.

Having done this, IT operations manager Matt Woodland found the existing SAN lacked the I/O performance for the new server environment and was stuck with a SAN that was near end of life.

“We wanted more speed. We had very high latency. To combat that we would have needed to add spindles but we didn’t need that extra capacity and didn’t want to support old kit that was near end of life, so we were looking at a forklift.”

Woodland said the drivers towards getting better performance from the college’s storage centred on the number of complaints and that users were experiencing “eight-second screen refreshes”.

Sometimes this was due to RAID rebuilds, said Woodland. “The way LeftHand striped data across drives slowed things down for three days if a drive needed rebuilding. It was also a complex piece of kit to manage for a small team of two infrastructure staff.”

Woodland’s team evaluated 10 storage vendors’ products to replace the LeftHand SAN and went through an on-site proof-of-concept with Nexenta, which supplies storage software that runs on commodity server hardware.

Unfortunately, the Nexenta trial wasn’t successful since it did not meet the college’s needs for replication and failover between boxes, said Woodland.

“It didn’t deliver what we wanted,” he said. “We wanted replication between the two boxes and for failover between them so we could flick from one controller to the other and update firmware without users experiencing any disruption.”

“But our experience with a loaded system saw 40 second dropouts, with VMs halting because they thought the storage had disappeared. Nexenta would only work the way we wanted at 6.5m apart or less, unless we paid £30,000 for the site replication module,” added Woodland.

Eventually, the college settled on Nimble Storage’s CS220G hybrid flash array with 960GB of RAM and 10Gbps Ethernet connectivity. It has MLC flash drives with SATA spinning disk for bulk storage and a total capacity of 7TB useable.

Nimble Storage came out of stealth in 2010, the creation of former Data Domain employees. Its iSCSI hybrid flash arrays marry bulk storage capacity on SATA spinning disk with capacity maximises via compression and data deduplication with multi-level cell (MLC) flash cache for speedy I/O.

The CS200 entry-level models house 8TB total raw capacity expandable to 76TB. Since the advent of Nimble OS 2.0 in August 2012 its hardware can be linked in a scale-out architecture.

Key benefits of the Nimble array for Woodland are its ease of setup and use plus its ability to handle drive rebuilds and to scale to meet future needs.

He said: “It took less than 24 hours to get the Nimble array into production and it has a nice GUI. On a day-to-day basis I can see the smiley faces on the IT guys’ faces. It’s saving us loads of space – going from four 3U racks to just 3U – we have the peace of mind that a firmware upgrade won’t take us down.”

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