I'm looking at buying a new laptop. My current system has an SSD for the OS and magnetic hard drive for media. All the new ones I'm looking at have a hard drive plus mSATA-based SRT cache (ex: Lenovo Y500). It looks like this won't be quite as good as a "proper" SSD, but much better than a magnetic drive alone.
Most of the systems I've seen ship with a 16GB mSATA SSD. I see options for 20, 32, even 64GB. The way I understand the technology, it somehow computes what you use most often and mirrors / "stripes" those blocks on the SSD, at the BIOS level. The thing I don't know is, how to calculate when you hit the point of diminishing returns. Is there some kind of instrumentation / diagnostic that can tell me what percentage of reads are hitting cache, and how often it needs to spin up the HDD?
I figure that in a couple of years, increasing the cache size will probably be a sound investment, as sizes increase and costs come down. I'd rather have actual data to base this decision on, if possible, though.
ETA: Two important things I found specific to the Lenovo machine I mentioned: a question about "ExpressCache", which is not quite the same as SRT, and a page from Lenovo about the ExpressCache software that actually does the caching, including instructions for finding out how full the cache is and how often reads and writes hit the cache. That last part is essentially what I was looking for!