VMware vSphere 5.5 introduces new functionality to leverage flash storage devices on a VMware ESXi host. The vSphere Flash Infrastructure layer is part of the ESXi storage stack for managing flash storage devices that are locally connected to the server. These devices can be of multiple types (primarily PCIe flash cards andSAS/SATA SSD drives) and the vSphere Flash Infrastructure layer is used to aggregate these flash devices into a unified flash resource.
You can choose whether or not to add a flash device to this unified resource, so that if some devices need to be made available to the virtual machine directly, this can be done. The flash resource created by the vSphere Flash Infrastructure layer can be used for two purposes: read caching of virtual machine I/O requests (vSphere Flash Read Cache) and storing the host swap file. This paper focuses on the performance benefits and best practice guidelines when using the flash resource for read caching of virtual machine I/O requests.
vSphere Flash Read Cache (vFRC) is a feature in vSphere 5.5 that utilizes the vSphere Flash Infrastructure layer to provide a host-level caching functionality for virtual machine I/Os using flash storage. The goal of introducing the vFRC feature is to enhance performance of certain I/O workloads that exhibit characteristics suitable for caching.
In this paper, we first present an overview of the vFRC architecture, detailing the workflow in the read and write I/O path. We then show some of the workloads that perform better vFRC through detailed test results. We conclude the paper with performance best practices guidelines when using vSphere Flash Read Cache.
Download White Paper: Performance of vSphere Flash Read Cache in VMware vSphere 5.5
