Now that the upper performance limit has been reached, perhaps a more real-world relevant test would show what this level of performance can achieve. A PCMark Vantage run should do nicely.
The HDD component of Vantage puts in one of the highest scores around at 622865 points. Without caching, the distressed Mushkin Chronos Deluxe could only manage a score of 52877. Each scoring component is moving at least 1700MB/s. These are fairy tale numbers, and just the beginning of what could be possible with such an arrangement on a faster system. The midrange components used here are fast, but still outclassed by much faster systems. Intel’s X79 motherboard and Sandy Bridge – E processors could very well crush these mainstream components.
All things considered, the IO performance and huge throughput that RAM provides when acting as cache for a SSD is a wonder to behold. Further, getting more performance when overclocked is just more icing on a hellaciously-fast cake. Low and high QD randoms, sequential, access times, and IOPS are all marvelous when operating out of the cache.
But there are some caveats. First, since RAM is volatile, the cache is not persistent. When the system turns off, the cache disappears. More importantly, the risk of data loss is omnipresent — if FC is caching writes to RAM, any fault with the RAM or sudden system crash could result in lost or corrupted data. Using ECC RAM where possible could help in this respect, but it is seldom seen in most enthusiast systems.
The upside is obvious, though. In specific applications, the performance increase could pay serious dividends. If an application is heavily dependent on storage performance, RAM caching can yield incredible performance increases over SSDs alone, much less traditional spinning media. FancyCache is easy to set up, and much more convenient that traditional RAM drives.
Caveats aside, the worst case scenario when using FC with a SSD is that performance will only be as fast as the SSD. In the best case scenario, almost all accesses occur directly from the RAM, and performance skyrockets. It’s either fast or faster.
Romex Software is currently beta testing FancyCache. As such, it’s not yet for sale but freely available to test. There are many facets and possibilities with FC, and the surface has only yet been scratched.
Just for kicks, one more test:
One last run of 4K random reads at a QD of 4 yielded the highest numbers yet — 765137.3 IOPS. Not bad for a few minutes of tweaking and overclocking. Still, the little-2500K-that-could was maxed out, and it’s bigger brothers could probably reach nearly one-million IOPS. The 2500K is a fine piece of kit, but in these situations a bigger hammer is called for.
One day, all storage media could be this fast. It sure won’t be anytime soon, but perhaps in the future, as new technologies supplant the NAND flash used in today’s SSDs. For today, if you can utilize the raw, unadulterated speed, there are brilliant performance increases to be had. But for most uses, the bottleneck just gets shifted to other components, and such speed increases could be hard to realize.
It is also perilous to make blanket statements concerning RAM caching. In a worse case scenario, it may not help much. But under certain conditions, there is no substitute. It is similar to a RAM drive in some respects, but FancyCache exhibits a level of flexibility unmatched by RAM drives.
FancyCache, freshly off a new beta revision, is certainly worth a try. Romex is aiming for an eventual commercial release, though some bugs are still being ironed out. With the potential pitfalls in mind, the potential benefits are certainly worthy of investigation. It’s most definitely a topic that requires more insight, but it is unquestionably interesting.