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This is not a hybrid drive, it is two drives as evidenced by the picture of the iMac that Phil Schiller showed. This is more akin to "tiered storage" which has

This is not a hybrid drive, it is two drives as evidenced by the picture of the iMac that Phil Schiller showed. This is more akin to "tiered storage" which has existed before, just not in the consumer space which prevents more/different challenges.

tomkinstinch 14y ago
I see, thanks; I haven't had a chance to watch the Keynote yet. Do you know how difficult it would be to set up something comparable using two drives (HDD+SSD) under, say, Ubuntu?
- brian_cloutier 14y ago
  I don't know about Ubuntu, but apparently Windows Vista and 7 have something very similar. http://en.wikipedia.org/wiki/ReadyBoost http://en.wikipedia.org/wiki/ReadyBoost
  - cokernel_hacker 14y ago
    Not even sorta similar, "ReadyBoost" is a cache "Fusion Drive" provides the union of space. They are in the same vein of "hide the slowness of rotational media" but that is a pretty huge vein.
    - brian_cloutier 14y ago
      In the Fusion Drive example, 3TB of hard drive is combined with 128GB of flash. The union of space is 3.125 TB, compared to the 3TB you would get with a cache. That's just a 4% increase in space that the Fusion Drive gives you over what a cache would give you. You can call it whatever you want, but I'm going to call them similar.
      - cokernel_hacker 14y ago
        And "just" a 32x increase in flash size.
  - rhplus 14y ago
    Not ReadyBoost, but ReadyDrive: http://en.wikipedia.org/wiki/ReadyDrive#ReadyDrive http://en.wikipedia.org/wiki/ReadyDrive#ReadyDrive
- fusiongyro 14y ago
  Well, if I wanted to achieve this today and I had an HDD and SSD in this computer, I'd mount /home and maybe /var on the HDD and everything else on the SSD. I usually go with a three partition setup (/boot, /, swap) and even that just with /home on the HDD would get you 3/4ths of the way there.
- wtallis 14y ago
  There are a couple of block-level cache systems in development, but that haven't yet been accepted into the mainline kernel. The one most suited for desktop SSD+HDD use right now is bcache, which is aiming to hit the kernel staging area next year. Facebook's flashcache is the other main contender. Both offer writeback and writethrough caching, but they differ in their policies for what kind of I/O skips the cache. Bcache tries to detect sequential I/O and send that straight to the backing disk, and organizes the I/Os sent to the SSD in a manner that tries to go easy on the SSD's wear leveling and garbage collection algorithms. Flashcache, on the other hand, tries to use the SSD to cache chunks of information that fit the SSD's page size - smaller I/Os skip the cache, which is probably the exact wrong thing for desktop workloads.

tomkinstinch 14y ago

I see, thanks; I haven't had a chance to watch the Keynote yet. Do you know how difficult it would be to set up something comparable using two drives (HDD+SSD) under, say, Ubuntu?

brian_cloutier 14y ago
I don't know about Ubuntu, but apparently Windows Vista and 7 have something very similar. http://en.wikipedia.org/wiki/ReadyBoost http://en.wikipedia.org/wiki/ReadyBoost
- cokernel_hacker 14y ago
  Not even sorta similar, "ReadyBoost" is a cache "Fusion Drive" provides the union of space. They are in the same vein of "hide the slowness of rotational media" but that is a pretty huge vein.
  - brian_cloutier 14y ago
    In the Fusion Drive example, 3TB of hard drive is combined with 128GB of flash. The union of space is 3.125 TB, compared to the 3TB you would get with a cache. That's just a 4% increase in space that the Fusion Drive gives you over what a cache would give you. You can call it whatever you want, but I'm going to call them similar.
    - cokernel_hacker 14y ago
      And "just" a 32x increase in flash size.
- rhplus 14y ago
  Not ReadyBoost, but ReadyDrive: http://en.wikipedia.org/wiki/ReadyDrive#ReadyDrive http://en.wikipedia.org/wiki/ReadyDrive#ReadyDrive
fusiongyro 14y ago
Well, if I wanted to achieve this today and I had an HDD and SSD in this computer, I'd mount /home and maybe /var on the HDD and everything else on the SSD. I usually go with a three partition setup (/boot, /, swap) and even that just with /home on the HDD would get you 3/4ths of the way there.
wtallis 14y ago
There are a couple of block-level cache systems in development, but that haven't yet been accepted into the mainline kernel. The one most suited for desktop SSD+HDD use right now is bcache, which is aiming to hit the kernel staging area next year. Facebook's flashcache is the other main contender. Both offer writeback and writethrough caching, but they differ in their policies for what kind of I/O skips the cache. Bcache tries to detect sequential I/O and send that straight to the backing disk, and organizes the I/Os sent to the SSD in a manner that tries to go easy on the SSD's wear leveling and garbage collection algorithms. Flashcache, on the other hand, tries to use the SSD to cache chunks of information that fit the SSD's page size - smaller I/Os skip the cache, which is probably the exact wrong thing for desktop workloads.