Almost all external storage arrays cache I/O in DRAM or NAND flash; however, storage caching may be minor with all-flash arrays due to reduced overall savings. The following are some instances of how vendors use caching.
Avere Systems has a cache appliance that allows NAS storage to be extended to geographically distant data centers or even the public cloud. This is deployed as a virtual appliance rather than physical hardware in the public cloud.
There are also Microsoft (StorSimple) cloud caching products that cache data produced and read from Azure, as well as Panzura Global File System appliances that cache file data locally in either a public or private cloud.
Agile Storage caches write I/O in NAND flash on the premise that it will be reread quickly. NVRAM, on the other hand, is often used to cache information before it can be written to disk.
For a secondary layer with less often accessed data, Hewlett Packard Enterprise 3PAR uses flash as an extension of DRAM. This technology, known as Adaptive Flash Cache, allows flash to enhance array caching capability without the need for additional DRAM.
The majority of software tools for boosting performance are available at the OS layer. Enmotus, for instance, has a range of devices for enhancing traditional disk-based performance utilizing flash for workstations and servers, while Intel's Cache Acceleration Application runs with its SSD products.
The application is compatible with Windows and Linux and may be operated as a virtual machine on any hypervisor. Other OS-based caching products include SanDisk's ION Accelerator, Samsung's AutoCache, and XtremCache (EMC).
Suppliers provide I/O acceleration for both NAS and block protocols within the hypervisor. PernixData, for example, interfaces with the VMware ESXi kernel and enables for the usage of both DRAM and NAND memory to speed up VM I/O. Write I/Os are duplicated between numerous hosts in a cluster when DRAM is employed to protect against hardware failure.
For virtual machines, the Infinio Accelerator software caches both NAS and block-based I/O. This is accomplished by using a virtual machine (VM) on each VMware vSphere host as a cache, which leverages DRAM within the virtual machine.
SanDisk, on the other hand, offers caching under its FlashSoft brand. vSphere 6 and Microsoft Hyper-V (and Server) are supported in the most recent release, 4.0, whereas older versions support Linux and vSphere ESXi 5.x.
Finally, Atlantis Computing offers two caching systems, one for virtual server environments and the other for VDI (ILIO) (USX).
ILIO provides both persistent and nonpersistent desktops using DRAM with a high level of deduplication, resulting in a significantly lower total cost of ownership for VDI than external flash-based storage.
