Solid-State Drives Settling in as Caching Solution
The more experience IT professionals gain with SSDs, the more obvious it becomes that SSDs will primarily serve as easily scalable cache for high-transaction servers and networking devices.
While it's true that adding SSDs to bulk storage will boost capacity and help off-load critical data from short-stroked hard disk drives, they may not be the most cost-effective solution for the average storage farm. The best way to get your money's worth, then, is to leverage that blistering-fast I/O where it will do the most good: as high-speed cache.
Adaptec is one company that seems to be heading in this direction. In the new MaxIQ cache solution, the company pairs the Intel X25-E drive with controller software from Microsoft (with maybe a few Adaptec tweaks thrown in) to create a high-speed cache for heavy transactional workloads. In its own benchmarks, the company says it more than triples I/O performance over non-cached solutions, representing perhaps a 70 percent reduction in both capital and operating expenses. The company hopes to package the system with its various RAID controllers to create high-performance hybrid arrays.
It also might pay to keep an eye on Infortrend. The company makes a good argument that SATA-ready SSDs can achieve performance equal to SAS-based HDD configurations at dramatically lower price points. And even adding SSDs to the server node to handle read/write cache on a unified storage system like the EonNAS 5100 can increase the performance by about 30 percent for only about a 10 percent price bump.
Realize, of course, that adding SSDs as a new cache tier will come at the cost of a little systems integration, according to Mark Teter, CTO of technology consulting firm Advanced Systems Group. For starters, you'll need to upgrade to an advanced file system like NILFS (New Implementation of a Log-structured File System) or Sun's Zettabyte File System (ZFS). And make sure you can accommodate the fact that some I/O writes may be slower in Flash than in NVRAM.
Most SSD cache solutions will likely be deployed as part of hybrid SSD/HDD systems. It's a way to both leverage existing hardware and to establish multi-tiered solutions for servers that are running multiple types of workloads.
In that way, the early predictions of SSDs in the enterprise have come true: SSDs are here to partner with, not replace, magnetic media.