QLogic's technology for clustered cache storage on SAN adapters will hit the market this month in the form of adapters with integrated 200GB or 400GB flash cards.
The company announced the technology last year and called it Mt. Rainier. It will let enterprises add cache storage to physical servers just by installing a QLogic Fibre Channel adapter and one driver, and pool multiple caches across a cluster of servers, according to the company.
The first Mt. Rainier product will be the FabricCache 1000 Series adapter, available with two sizes of PCIe flash drives, which will go on sale to enterprises by the end of this month through QLogic resellers. Those resellers will set the price of the FabricCache products, said Chris Humphrey, vice president of corporate marketing. Adapters with SAS SSDs will come at an unspecified later date, and QLogic is still talking with server vendors about possible Mt. Rainier components built into servers.
The FabricCache adapter can connect a server to a SAN via Fibre Channel but also contains solid-state storage capacity for a cache of the most-used data on the SAN. The product also includes the software and the processing power to operate the cache, so it doesn't tax the server, according to QLogic. To applications running on a server or a cluster, the cache looks like SAN storage, but it's faster to access.
By installing FabricCache adapters in more than one server in a cluster, enterprises can create one large, shared cache available to all the applications running over the cluster. For example, in a cluster of four physical servers, each of which has a FabricCache with a 400GB flash component, applications will have access to 1.6TB of cache, Humphrey said.
The cache is agnostic to both hypervisors and applications, according to QLogic. When a virtual machine moves from one physical server to another within a cluster, the cache keeps the most-accessed data available.
The FabricCache is a simpler alternative to installing an adapter, a cache, and cache management software separately, Humphrey said. Because it uses a single driver, FabricCache is easier to implement and manage, according to QLogic.
A Fibre Channel adapter is a good place to put a solid-state cache for enterprise servers, because most of the customers that would be interested in this type of cache need to buy the adapter anyway, said Jim Bagley, senior analyst at Storage Strategies Now.
However, the biggest benefit of FabricCache is its integration into a Fibre Channel fabric, which forms the backbone for pooling the caches across a cluster, Bagley said.
"The only way to share these flash cards across a cluster is by using a fabric," Bagley said. Pooling caches across a cluster should allow enterprises to make better use of flash as they virtualize their workloads to balance out computing needs, he said. Competing vendors of server-based flash, such as Fusion-IO, aren't even close to developing such a pooling technology, according to Bagley.
When a workload moves from one physical server to another and has to go across the Fibre Channel fabric to reach its cached data, that should be slower than accessing it on the same server, but not by much, Bagley said. Testing by Storage Strategies Now showed a difference of about 7.5 percent, he said. But that's far less than the latency involved in "warming up" a new local cache after the workload is moved, he said.
Even higher speeds may be in store given that QLogic's adapter family extends to Ethernet, Bagley said. While the current FabricCache adapter uses 8Gbps (gigabit-per-second) Fibre Channel, Ethernet is available at speeds of 40Gbps and more. "This is just the opener," Bagley said. QLogic said it has 10Gbps Ethernet versions on its road map for Fibre Channel over Ethernet and iSCSI.
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