While it's true that you can add SSDs to pretty much any storage device on the market today, from a four-bay Drobo Mini to an EMC VMAX, I'm convinced that getting a small amount of flash and a lot of disk capacity to really sing and dance requires a fresh design. When you add flash to a traditional disk array you get the storage equivalent of what in the car world is called a mild hybrid. A few years ago, Chevy slapped an electric motor on its Silverado pickup truck. While the new "hybrid" version did get 10% better city mileage, the benefit of that electric motor is nothing like what you get from a designed-from-scratch hybrid like a Volt or Prius.
Flash and disk drives are different enough that arrays have to store data in each medium differently. While traditional arrays with SSDs do perform substantially better than just drives alone, generally they can't offer the level of efficiency that a designed-from-scratch hybrid will.
Tegile's Zebi unified storage systems use a multitiered cache architecture where DRAM and flash are used as cache in front of 7,200 RPM nearline SAS drives. The Metadata Accelerated Storage System (MASS) combines thin provisioning, compression and data deduplication with an efficient redirect-on-write snapshot provider to optimize the use of both flash and trash (the 7,200 RPM drives). Since most of the active data will be cached in the SSDs, data reduction shouldn't have a significant performance impact but will bring the effective cost per gigabyte stored from about $15 to $3 or $4 dollars.
While most of the other players in the next-generation hybrid storage market present a single tier of storage from their systems, Tegile has chosen to also expose some of the SSDs in the Zebi as a dedicated high-performance tier of storage. Each system now has a fixed number of SSDs dedicated to cache and to the high-performance tier, but the Tegile folks tell me the ability to change SSDs from one purpose to the other dynamically is on the roadmap.
This week, Tegile announced two new, beefier Zebi systems:
• The HA2400, which comes with 96 Gbytes of DRAM cache, 10 200-Gbyte SSDs and 14 1-Tbyte disks at a $168K MSRP; and
• The even faster, all-solid-state new HA2800F, which has 22 200-Gbyte SSDs and can deliver a claimed 200,000 IOPS.
Each system can be expanded with drive shelves containing both SSDs and disks or a high-density, disk-only shelf that holds 72 Tbytes in 4u. Frankly, Tegile isn't trying to compete in the all-solid-state market and expects almost all the HA2800Fs that it sells to go with disk-expansion units. Tegile tells me scale-out expansion is on its roadmap but isn't saying anything about when we'll see it.
Since the Zebi is a unified storage system, an organization could connect its OLTP databases and other IOP-hungry applications to the system via Fibre Channel or iSCSI over 10-Gbps Ethernet to all SSD LUNs and the users to home and other shared directories via CIFS or NFS all on the same system.
Organizations looking for 10 to 150 Tbytes or so of fast storage should evaluate at least one of the next-generation hybrid players, including GreenBytes, Starboard Storage, Tintri, NexGen and Nimble in addition to Tegile.