Marketing firm shuns NetApp for VMware VSAN and HGST server flash

Grass Roots was struggling with capacity and performance on its NetApp SAN so it deployed VMware VSAN on servers with HGST PCIe server flash and helium HDDs

Hertfordshire-based marketing company Grass Roots has migrated storage for key SQL-based applications from NetApp storage to VMware VSAN that uses HGST PCIe server flash and helium-filled hard drives and gained huge boosts in IOPS and reductions in latency.

Grass Roots offers a range of services that range from website and applications development and hosting to real-world meetings and events management. All its services are run from its greater London datacentre plus public cloud capacity, with apps delivered via 650 VMware virtual machines (VMs) on 110 physical servers.

The firm had a NetApp FAS3220 SAN in place, which they had specced for two years’ worth of capacity increases at 50% year-on-year growth. As that two-year period elapsed, Grass Roots head of group hosting Simon Kearney began to experience performance issues, such as increased latency.

“Towards the end of the two years, the NetApp SAN started to become a bottleneck with latency between the VMs and storage of 8ms to 10ms and for snapshots during the back-up windows of 100ms to 300ms, both of which were less than optimal,” he said.

Rather than upgrade the SAN, Kearney opted to take the apps with the highest performance requirements and move them to three servers running VMware Virtual SAN (VSAN) software and equip the hardware with one HGST Ultrastar SN150 1TB PCIe flash and eight Ultrastar HD6 6TB helium-filled drives per box.

VMware VSAN aggregates server-attached disk (DAS) into a single pool of storage that can comprise spinning disk HDDs with flash disk for high-speed metadata. Using software acquired from Virsto in 2013, it is able to provide speedier write access to virtual machine storage by logging write requests and making them sequential rather than random.

Kearney said the move to a tiered storage model between the NetApp SAN and server-based VSAN has provided ample performance for the organisation’s most demanding applications.

“The tiered model gives us the option to expand performance and capacity flexibly in the distributed storage without huge investment and we’ve regained some headroom for our key applications. 35,000 IOPS would have crippled the SAN, but now we get that regularly. Likewise, we were seeing latency of up to 8ms and now that’s down to less than 1ms,” he said.

“Adding a sever with CPU or storage is a lot easier and cheaper than upgrading the SAN, and adding extra capacity and performance to VSAN is a run-of-the-mill task without disruption,” he added.

“Typically we’d spend around £150,000 for a SAN refresh, but the move to VSAN has given us the flexibility about where to spend and to gain headroom in the area we want it.”

How did Kearney feel about going down the VSAN road, to what is a relatively untested storage environment?

“We had some nervousness as we’re not typically a company to be at the bleeding edge, but we were able to do extensive testing for a month with some VMware and storage people. We got the SQL guys to provide their worst-performing queries and tested failure and failover scenarios to show what happens,” he said.

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