Call Center Workflow Management software is storage IO intensive since it involves ingesting and analyzing large volumes of audio. By caching from slower storage to in-host SSDs/DRAM, VirtuCache improved storage performance considerably thus improving the performance of Verint’s Call Center Workflow software running within VMs.
Verint’s Issues with VMware and storage
Verint’s EIS business is the market leader in Call Center Workflow Management (WFM) Software.
Their dev/ops tests and triages customer issues in their WFM software running in VMware VMs backed by a few hundred TBs of storage on HP MSA appliances. As a result large amount of audio and associated metadata from different customers are being continuously ingested and analyzed within their application. Throughput requirement across the cluster was ~ 3.2GBps . HP MSA appliances being primarily hard drive based couldn’t deliver this level of throughput and neither could their 8gbps FC network. As result, VM level latencies were frequently higher than 100ms.
One solution was to upgrade to 32gbps FC network and large amounts of all-flash storage. This was ruled out due to the costs involved.
VirtuCache was a cheaper way to get the same benefits as the upgrade to an all-flash array. By caching reads and writes from their MSA appliances to in-host SSDs, latencies were much reduced even at peak throughput of 400MBps, and without requiring Verint to replace their 8gbps FC SAN and slower MSA appliances. Also since most reads are now offloaded from the SAN to in-host SSDs, pressure on their FC network is much less. Lastly, SSDs installed in each host are much cheaper, since these SSDs are bought retail. In comparison storage appliance SSDs are considerably more expensive for the same SSD make and model.
Verint Dev/Ops Infrastructure and Workload Characteristics.
Servers – HP BL380s running VMware 5.5
Storage – Hard Drive based HP MSA appliances on 8gbps Fiber Channel SAN
The ability to deliver low latencies even at 400MBps VM throughput was required. This was primarily audio and associated metadata ingested and managed within Verint’s application. Since VM densities were high, IO was mostly random.
VirtuCache was deployed on each ESXi host, caching both reads and writes from Datastores on HP MSA Datastores to a 960GB Samsung SM863 SSD in each host.
With VirtuCache caching to in-host SSD, VM level latencies were now consistently under 10ms, even at high 400MBps VM level throughput.