Originally Posted by SolipsismX
we do know that the OS will determine which files will remain on which drive and it will do so more intelligently than simply looking at frequency of use.
They are able to preload the OS and apps onto the SSD when you buy it, which other setups can't do but I doubt they'll have priorities for certain files over others such as always keeping the system folder on there. The benchmark test from before showed a large file transfer of over 128GB and it was SSD speed for most of the transfer and then dropped to the HDD speed so I'd have to assume they flushed the entire SSD first somehow. If the SSD gets filled up, as soon as you copy something else onto the Fusion drive, it will have to just send it to the HDD like other setups.
Originally Posted by SolipsismX
Here is a 500GB Seagate Momentus XT
Check out those random reads and writes between SSDs, HDDs, and hybrid-HDD. As you note, since the hybrid-HDD is just cache it's going to act pretty much like an HDD.
That's the current hybrid drive though. It doesn't use SRT, though it's supposed to store frequently used data, you just can't keep very much data in under 8GB. It's going to get confusing because the ones coming in next year will be called hybrid drives but use an entirely different setup.
2010 - hybrid drives launched, same as what we have now with just a 256MB-8GB cache and some adaptive memory to check frequent blocks - not enough flash, not fast, not like Fusion
2011 - Intel SRT, merges up to 64GB SSD cache with HDD but requires driver/BIOS-level management
2012 - Apple Fusion merges any SSD with HDD (4GB cache) - OS-level management
2013 - new hybrid drives with SRT (firmware-level), likely merge 32-64GB SSD with HDD, new internal management that can do better caching
Apple's advantage over an SRT setup will be the SSD size. If the cache is too small as tested here:
it can end up having no benefit at all. It's not clear if the caching management will differ significantly between them. I'd expect Fusion to put the most frequently accessed blocks on just like SRT. If future hybrid drives only come with 32GB though, Apple's 128GB will be a huge advantage.
They all seem to be working towards the same goal but Apple's setup will work best for the most part and they were first to use OS-level management and a large SSD. That's the benefit they get from selling both the software and hardware.
For end users, if the 2013 hybrid drives use a 64GB cache, I'd expect them to see mostly the same kind of results you get from Fusion and there are some benefits like it won't have any software incompatibilities like Fusion does and it will work on any OS. I'm not sure if you'll be able to boot Linux on a Fusion drive. You can also put multiple drives in together - for example the Mac Pro can have 4 SRT hybrid drives in RAID10.
As usual when Apple does something new, people are quick to point out it's not new at all but just like with the iPhone, while smartphones preceeded it, they weren't done properly. No implementation of a hybrid system prior to Fusion has really shown a significant benefit and if it has, has been difficult to setup. Apple has made it easy to configure and beneficial from the day you buy the machine and they've made the right choice with SSD size.