I’m a lover of solid state drives and flash memory. So it shouldn’t be much of a surprise to see this post dedicated to Apple’s Fusion Drive solution.
It turns out that the Fusion Drive isn’t like Intel’s Smart Response Technology at all, it’s more like what I’ve been doing with my solid state drive and my 1TB Western Digital drive. I’ll let AnandTech explain it:
That 4GB write buffer is the only cache-like component to Apple’s Fusion Drive. Everything else works as an OS directed pinning algorithm instead of an SSD cache. In other words, Mountain Lion will physically move frequently used files, data and entire applications to the 128GB of NAND Flash storage and move less frequently used items to the hard disk. The moves aren’t committed until the copy is complete (meaning if you pull the plug on your machine while Fusion Drive is moving files around you shouldn’t lose any data). After the copy is complete, the original is deleted and free space recovered.
So in essence, it’s just OS X is shuffling files around based on usage; trying to get the most frequently used files into the 128GB solid state drive. I’ve been doing something similar but manually. I’ve used SteamTool to temporarily move Steam games onto my SSD in order to take advantage of quicker access times. Apple essentially that concept, automated it and makes it invisible to the user.
It’s a sound idea in theory but I have questions which I suspect AnandTech’s future in-depth review of the new iMacs will cover.
- How many accesses does it take before a file is moved over to the SSD?
- When does the shuffling of files happen? During idle? At a set time?
- If there is space on the SSD, will an application or file stay on the SSD or will it be regulated to the HDD after a period of time has passed without a single read or write to it?
These stop gap solutions are interesting but they’re simply stop gap solutions. I cannot wait for the day when 1TB SSDs are at $100. By then, all this shuffling will be nothing more than distant memory. But for now, it makes for interesting discussions, I guess.
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