Why a County Hospital Selected VirtuCache Versus Using HPE MSA’s Internal Caching / Tiering Functionality?
Contra Costa County Hospital is a 800-bed government hospital in the San Francisco-Bay Area.
Their IT department is using HPE MSA storage and ESXi compute to run their EMR, imaging and other critical care applications. They were seeing high storage latencies from their HPE MSA appliances, because of inadequate MSA cache capacity, large amounts of small block IO, and because some of their applications were write intensive. They used VirtuCache caching to in-host PCIe SSDs to improve the storage performance of their VMware and storage infrastructure.
This article explores their use case in detail and how VirtuCache improved the performance of their hybrid MSA.
How Central Valley Health Saved Money by Using VirtuCache Instead of Replacing HDDs with SSDs in their Dell VRTX?
Central Valley Health Networks is a healthcare collaborative providing shared IT services to various community hospitals and clinics in the Central Valley region of California.
They are using Dell VRTX hyper-converged appliances to host their IT applications. Dell VRTX is a 4-blade hyper-converged appliance with an integrated switch and internal shared SAS storage. Dell VRTX is cost-effective and popular in the midmarket enterprise segment.
With increased VM density, the onboard shared Hard Drive based storage started to slow down. CVHN had two options to fix this problem, either replace all their HDDs with SSDs or use VirtuCache to cache from their existing HDD based Datastores to a PCIe SSD installed in each VRTX blade. Since this latter option was higher performing, considerably less expensive and less disruptive, they chose to go with VirtuCache caching to one in-host 2TB Intel P4600 PCIe SSD, in each of their four VRTX blades.
This post explores their Dell VRTX VMware infrastructure, cost & deployment details of VirtuCache, and before/after tests with VirtuCache.
Gardner Packard Health have radiology related applications running in VMs. Radiology applications process large amounts of images and related metadata, typically in small block sizes. At this customer this workload was also write intensive. It is such write intensive small block workload that stresses storage appliances considerably. This is because such workload requires large amounts of CPU, and since mid market storage appliances have smaller CPUs in their storage controllers, the storage infrastructure becomes controller CPU constrained. This is true of most mid market all-flash and hybrid arrays. Some hybrid arrays don't even cache small block writes. VirtuCache adds value to such appliances by caching all writes to in-VMware host cache media.
Tourbillon Capital have a proprietary trading application that required under 5ms write latencies at all times. This problem was compounded by the fact that they also had a stretched SAN cluster that spanned a WAN link, which meant that writes from the application had to be committed to the SAN array in the local datacenter and to another array in the remote datacenter. Though the WAN link between datacenters was 10gbps, they still couldn't consistently get sub millisecond latencies across this link, which resulted in frequent high write latencies at the application level.
Tourbillon solved this problem by using VirtuCache to cache writes to large amounts of local in-host RAM, with a copy of the write cache also replicated to RAM on another host in the same cluster. Within VirtuCache, we also ensured that cached writes and its replica didn't traverse the WAN link. As a result, write acknowledgement to the VM (application) occurred when writes were cached to two places - to RAM in the host where the VM resided and to RAM in another host in the same datacenter. In this way VirtuCache ensured that VM level write latencies stayed below 5ms at all times.
This link on VMware's website states that our host side caching software is on their Hardware Compatibility List (HCL) for VMware's API for IO Filter (VAIO).
Its great to be on VMware's HCL since some customers now might feel more comfortable with our software. But just to be clear, this listing in VMware HCL, doesn't change either the features of VirtuCache, or the support escalation path for customers. We support all ESXi 5.x and 6.x versions in exactly the same way.
Since we have been asked this question by some customers, I want to clear up two misunderstandings about third party software that VMware certifies via their Hardware Compatibility List (HCL).