Reducing Write Latencies for Small Block Random IO in EMC Unity Storage
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.
Improving Write Latencies in a Stretched SAN Cluster for Trading Applications at a Hedge Fund
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.
VirtuCache is Listed in VMware’s VAIO Compatibility Guide for Host Side Caching Software
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).
Improving VDI Performance at Fairbanks Sewer and Water
Fairbanks Sewer and Water is a Utilities company in Alaska. FSW's IT department had deployed over a hundred desktop and server VMs.
Their end users of virtual desktops were complaining about long application load times, long boot times, cursor freezes, and general slowness in their VDI VMs, all classic symptoms of slow storage.
These VMs were spread across storage appliances from two different vendors. VirtuCache was ideally suited to improve the performance of these VMs, since it would do so across all their VMs, without requiring any reconfiguration of the appliances or networks, and without any regard to which appliances were hosting the VMs. VirtuCache caching from Datastores on these appliances to in-ESXi host PCIe SSD would completely mask the poor performance of these appliances.
Reducing Build Times for ServiceNow’s Dev/Ops
ServiceNow's Itapp Dev/Ops team wanted to improve build times for their dev/test infrastructure. They knew that storage latencies needed to be reduced considerably to achieve this goal. They ideally wanted to improve storage performance without upgrading their storage appliance or network.
To achieve this end, Virtucache was installed on each of their 3 ESXi hosts, configured to cache from Datastores on their HP 3PAR appliance to an in-VMware host 1.6TB PM1725 PCIE flash card.
VirtuCache was configured to cache both reads and writes for all VMs. VirtuCache automatically replicates the writes to another SSD on another host. This caching policy is called 'Write Back One Replica'. Write replication is done to prevent data loss in case of host failure. If a host were to fail, then VirtuCache would immediately sync the SAN from backup copy of writes (write replicas) that are on another host. In Virtucache, all caching operations, including write replication, are automatic.
Using VirtuCache, ServiceNow was successfully able to reduce code compile times in their dev/ops group to a third of what they were experiencing before.