Software Side: Caching Powered By Nvelo's Dataplex
For caching, OCZ leverages Nvelo's Dataplex. As far as software caching solutions go, this one is a little different. Intel's Smart Response Technology attempts to intelligently cache hot (frequently-used) blocks, leaving data it considers to be one-touch (unlikely to be requested again) on the hard drive. This is a natural consequence of the fact that Intel's caching implementation is tied to low cost and its 20 GB SSD 311. Just because it makes caching more accessible to mainstream customers doesn't mean Intel's approach is the most efficient, though. In contrast, OCZ's caching approach is not married to the valuation of the data. Instead, if data is accessed often, regardless of the pattern, it gets cached.
Another major difference between Intel's Smart Response Technology and OCZ's solution is the write-caching policies they use. The RevoDrive Hybrid is claimed to be a performance-driven caching product, which is why you pay $500 for it. As such, the Dataplex software controlling it is limited to write-back caching. Intel, on the other hand, lets you choose between a write-through (which it calls Enhanced) or write-back (also known as Maximized) strategy.
The difference is that write-through caching synchronously writes to the NAND and the hard drive. While you can still get significant performance gains in reads, naturally, writes slow down to the speed of a slow, 5400 RPM notebook drive, and there's nothing sexy about that. In a write-back configuration, however, the cache is written to first. Information is only moved to the hard drive when it's evicted from cache. As a result, writes do speed up, especially when you're working with a big 100 GB cache (rather than a smaller 20 GB one).
Now, write-back caching isn't necessarily faster. In a write-back cache, you have more cache management going on, tracking locations being written over. Given the overhead, write-through caching can be faster, especially when you're pushing a lot of random I/O. In lighter loads characterized by sequential workloads, however, write-back is the way to go.
If you've experimented with caching on a Z68 platform, you'll find the RevoDrive Hybrid to be a bit more restrictive (or, you could call it more specific). The Dataplex software only allows you to cache the boot drive. This means caching can only be enabled when you install Windows to the RevoDrive Hybrid and boot from it. As a secondary drive, it's possible to manually access the SSD and hard drive portions of the RevoDrive Hybrid separately, but they won't operate cooperatively as a caching solution.
If you try to enable caching with the Hybrid installed as a secondary drive, you can only cache your existing boot drive. This is kind of pointless, because you're losing out on the low-latency transfer that occurs within the RevoDrive Hybrid.
