Surveyor E.surv builds on Nimble hybrid flash arrays

House valuation surveyor E.surv retires creaking Dell EqualLogic iSCSI arrays and boosts IOPS with a pair of Nimble Storage CS240 SAN with front end MLC plus bulk SATA drives

House valuation surveyor E.surv has replaced its ageing Dell EqualLogic iSCSI SAN arrays with a pair of Nimble Storage hybrid flash devices and reaped up to 40% performance improvements, plus a 30% decrease in data growth due to on-board compression.

E.surv, which has about 1,000 staff and consultants logging into its systems, is one of the UK’s largest house valuation surveyor groups. 

It has a head office in Kettering plus satellite offices, with a workforce that is mostly mobile, logging into its datacentre systems via tablets and laptops to access Microsoft Exchange email, SQL Server and legacy plain text industry apps.

Its existing Dell EqualLogic iSCSI SAN was equipped with 10,000rpm SAS drives but was beginning to feel the strain in terms of I/O as data had grown and the number of people logging in had expanded, said E.surv systems and security administrator, Max Ashton.

Ashton said: “The EqualLogic array was getting old and not coping with the I/O load, in particular with Exchange, which had not been heavy when it was first deployed. The main problem was it was very slow to recover emails, retrieve files and suffered general performance degradation, in particular for the users at the head office and Hinckley satellite office.”

So, Ashton’s team began to evaluate a number of shared storage alternatives for the predominantly VMware environment and eventually settled on a pair of Nimble Storage CS240 iSCSI hybrid flash arrays with 12 2TB SATA and four 160GB multi-level cell (MLC) flash drives in each, and connected to servers via the 1Gbps LAN.

Nimble Storage is one of several startups providing hybrid flash storage arrays. These marry flash storage at the front end for hot data with spinning disk – often cheap, high capacity SATA – at the back end for bulk data, with compression or data deduplication between the two tiers.

So far, hybrid flash storage designed from the ground up is mostly a startup play and hasn’t been adopted by the big six storage suppliers, although most have given the ability to add flash drives to spinning disk arrays.

Ashton calculated that the company needed about 6,000 IOPS in total at the Kettering head office site (about 17 IOPS per user), but the Nimble Storage CS240s would provide up to 20,000 IOPS in total under favourable conditions, he said.

“The performance gain was immediate and apparent,” said Ashton. “It’s given us a lot of headroom in terms of performance and we’ve added more workload and seen no drop-off.”

Ashton calculated that E.surv had seen a 30-40% performance increase with data growth slowed by about 30% due to the compression.

“We have downgraded the EqualLogic arrays to the lab environment. I really like them but they were a bottleneck in our systems.”

Ashton has also been impressed with the compression used by Nimble between the front end MLC and bulk SATA. 

He said: “The compression has really made a difference to the bottom line – we haven’t needed to buy another shelf even after 18 months and I don’t expect to until the end of next year.”

Did E.surv need to think about the risks of going with a startup company rather than an established supplier like Dell?

Ashton said: “We did think carefully about going with a startup storage company and the board of the [owning company] LSL Property Services was very keen to assess the risk and discuss Nimble and its roadmap.”

Other vendors considered by Ashton’s team included: Dell Compellent – “We didn’t like the semi-automatic tiering as we don’t have the IT staff here,” said Ashton; Hitachi Data Systems – ditto; HP 3PAR – “too expensive”; Equallogic – “We didn’t like the inability to expand using extra shelves. You had to buy an entire new array.”

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