There’s been a lot of buzz in the SSD market in the past few months, including a public offering, multiple instances of major new funding, and commitments to SSD from the big storage vendors. Fusion-io, maker of Flash memory PCIe server cards, completed its initial public offering on June 9, closing at $22.50 a share and raising $237 million. Kaminario closed a $15 million series C funding round. Violin Memory, maker of flash memory arrays and caching systems, closed a $40 million Series C funding round shortly after raising $35 million in February. Pure Storage raised $28 million in venture capital even though its solution is still in private beta testing and has yet to be revealed. EMC has made a commitment to boosting several of its arrays with flash and of course Oracle bases its Exadata appliance on Flash. Anyone how knows anything about this market is probably already weary of hearing the phrase, “Flash is the new disk and disk is the new tape.”
Despite all this buzz and the general feeling that the SSD market is hot and getting hotter, it’s still relatively young, with many product categories and different types of solutions geared towards different applications. Before jumping in and taking advantage of what SSD has to offer it’s important to understand these differences, as well as what makes sense for your environment.
The SSD market is rife with different form factors and memory types. There are SSD PCIe cards, SSD “disks,” and SSD appliances. Sometimes SSD is used as a cache, sometimes main memory. And there’s Flash SSD and DRAM SSD. All of these choices have their pros and cons.
PCIe cards can be excellent solutions if you’re looking for a speed boost in a single server, as SSD is significantly faster than disk and the PCIe card form factor brings storage closer to the server processor than it would be in a disk form factor. These cards can be used either as a full storage tier or as a large cache for speeding up the most frequent storage reads and writes. Both can enhance I/O performance for many applications significantly.
It’s important to remember however, that PCIe solutions are only useful for accelerating applications in a single server. Just about all of these cards use Flash, which provides much faster reads than writes, so they are mostly useful for read-heavy applications, as opposed to online transaction processing. And finally, Flash memory has lifetime limits that can lead eventually to failure and significant data loss if you’re not careful. Wear leveling helps prolong Flash life, but it can also result in several chips failing in a short time period. These may not be the best solutions for mission critical applications.
SSD disk form factors are notable for their easy integration with RAID and other disk based configurations. They can also be used as a primary storage tier or as a data cache. Since an SSD “disk” can be installed directly in a RAID box, it can serve several servers and applications. However, in this configuration it’s often constrained by the I/O performance of a RAID architecture built for much slower hard disks. Most solutions are Flash based and so have similar write speed and life limitations as their PCIe counterparts.
Appliances are nice solutions because they sit outside the server and the RAID box. Not only can they offer access to multiple servers and applications, but they are not limited by either server or RAID architecture. This allows vendors to architect solutions that are purpose built for full SSD performance. Some are flash based and some are DRAM based. A flexible architecture can allow you to take advantage of the benefits both provide.
DRAM is inherently faster than Flash and provides both superfast random read AND write performance, so it’s an absolute killer solution for online transactions, especially if transaction volume translates directly into revenue. If you depend on live or almost live business intelligence and analytics to stay competitive, you should definitely look at a DRAM based solution as well. DRAM has no lifetime limitations, so you don’t’ have to worry about data loss or expensive replacements when the chips reach a certain number of writes.
So go out there and take advantage of what the booming SSD market has to offer. But make sure you do some homework first. Analyze the I/O characteristics of your applications and then choose the SSD solution that provides the best fit. Don’t get burned.
Tags: analytics, big storage vendors, business intelligence, caching, DRAM, Flash memory, I/O Performance, Online Transaction Processing, online transactions, PCIe cards, public offering, RAID, reads, ssd form factors, ssd market, storage arrays, writes