Interesting stuff, Mike. I wish I could come over with my MHT2080AT and see how it compares to the rest of the drives you've done so far, but we're about as far away from each other as it gets without leaving the North American continent.
I think the importance of cache size needs to be addressed; different operations rely different amounts on cache. It's also important to note that the way of looking at differing cache sizes is critical as well. Unlike in some cases where it would require continuous doubling of memory size to attain double the performance gains, cache works differently. For example, 8MB of cache does not necessarily command a double 2X gain of performance gain from having cache memory as that of 2MB; no, it's 6MB more cache to work with in general. Not only does it allow four times the amount of same-size data samples to be cached, but it enables caching of much larger data samples at the same time, so increasing the cache from 2MB to 8 MB is more effective than people would be led to believe.
Going from 8MB to 16MB is an 8MB gain, which may look like a doublling of cache capacity, and perhaps, to some people, maybe an effective doubling of cache-performance-increase effect over 8Mb, but that, again, is not true. Not only can the drive now cache twice as many samples of the same size as 8MB cache, but now it can cache data samples ranging above 8MB up to 16MB in size, which opens up incredible gains in performance.
What I'm saying is, let's say you're caching 1MB samples, for example. The 2MB cache only can cache 2 samples. The 8MB cache can cache 8 and the 16MB cache can cache 16 samples. That would indicate a 4X increase in cache hits for 8MB over 2MB, and 8X increase in cache hits fot 16MB over 2MB, but that's barely skimming the surface. Now look at 3MB data samples. The 2MB cache cannot even cache a 3MB sample; therefor, for a 3MB data sample, there isn't any benefit from caching at all. Meanwhile, the 8MB cached drive can cache two whole 3MB data samples, and the 16MB cache can handle a full 5 samples at 3MB! You're looking at "infinite"% gain over 2MB cache for 3MB samples and 150% gain over 8MB cache for the 16MB cache.
I'm not saying that I believe your results when the benches indicated the 16MB cached 60GB Toshiba to outperform a 180GXP, since that's highly unlikely, but that this drive can crush anything else in the category with 8MB of cache, especially 2MB of cache? Oh heck yes!
Now, the main question is: how much does your software benefit from caching? Again, if you're a user that's constantly hitting the same data over and over, the cache will help you much more than someone who works with brand new or extremely large datasamples with each drive hit. In other words, for reading operations, browsing the web will accelerate incredibly with larger cache, but a Photoshop artist working with 200Mb, 16-bits/channel CMYK high-resolution images probably will not benefit nearly as much. In those cases, it's all about raw transfer rate from the physical storage medium; nothing helps that out better than RAID. On writes it's a little different, as the cache memory can act as buffer memory.
Contributing Writer, SPCR
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