[l008com]

I read this rumor about new MacBook Pro's coming with a 16 GB SSD "boot disk" along with a normal hard drive for regular storage. So, how would this work? Would they just show up as two different disks? 16 GB is kind of small, once you start installing Apps. Or has Apple created some fancy new technology, that let's you see just one drive, and the computer automatically puts the most appropriate things on the SSD, and lets you access them invisibly as if it were all on a single volume?

I'm extra curious about this because I'm just about to replace my old set of hard drives in my Mac Pro, with a brand new 1 TB HDD and a 90 GB SSD drive. I had planned on installing my OS and Apps on the SSD, and keeping just my user folders on the HDD. But if Apple has some new technology to transparently manage SSD's and HDDs together as a single volume, then I can save a bunch of money by getting a much smaller SSD for my Mac Pro. (note the lack of "Book" in this second paragraph)

[Spheric Harlot]

Originally Posted by l008com 

I read this rumor about new MacBook Pro's coming with a 16 GB SSD "boot disk" along with a normal hard drive for regular storage. So, how would this work? Would they just show up as two different disks? 16 GB is kind of small, once you start installing Apps. Or has Apple created some fancy new technology, that let's you see just one drive, and the computer automatically puts the most appropriate things on the SSD, and lets you access them invisibly as if it were all on a single volume?

That is the reason I didn't buy into those rumors - it's difficult to believe that this would be ready and fail-safe already.

Next revision, with 10.7, sure.

What happens when something like Logic assumes it will be installing all its 42 GB of libraries into /Library/Application Support and /Library/Audio?

[uzit88]

The boot time would be immense though, I think the SSD would be only used for booting and the switch to your normal drive.

Complete guess though!

[Spheric Harlot]

Originally Posted by uzit88 

The boot time would be immense though, I think the SSD would be only used for booting and the switch to your normal drive.

Sense, you make none.

[P]

There is a problem with that plan. Flash longevity has been dropping with each threadshrink, so for the 34nm gen you can write 5000 times and for the 25nm gen it's 3000 times. This is not a big deal for a drive that is 256 gigs or so, because you can rotate around which cells you write to - even if a cell fails a write, you can still read from it and move that data somewhere else - so in total you can write 750 TB to a 250 GB drive before it even starts to fail. In practice, other parts of the computer would die first, and an HD is fairly likely to fail before that as well (for other reasons).

The idea here seems to be to take a small 16GB SSD and use it for what is essentially a write cache. That would make the flash run out fairly quickly. The lack of parallelism would also limit the bandwidth, all for a cache that is barely bigger than the RAM anyway. No, if it is used at all, it will work like the flash in the Momentus XT hybrid drives: a straight read cache, where frequently used files can be accessed quickly directly from the flash. The frequently used files are rarely changed, so write limits won't be an issue. Add one more fact: OS X already identifies frequently used files and puts them in the fastest sector of the HD. The same mechanism could be used to fill this cache. The only issue is flash bandwidth (the flash advantage is access time - latency - but the high bandwidth comes from connecting lots of chips in parallel. 16GB will be only one or two chips, so the bandwidth will be lower) but it's an interesting idea to help the rather abysmal performance of a 2.5" HDD.

[uzit88]

Originally Posted by Spheric Harlot 

Sense, you make none.

Sorry, I try my best.

[Spheric Harlot]

Did you intend "immense" to be read has "tiny" - as in, "wicked fast"?

Never mind, then.

[uzit88]

By immense I meant super/wicked/awesome fast! lol

[Salty]

I was really disappointed when this rumour turned out not to be true. I'm still gonna use an Optibay to put an SSD as my boot drive later on though.

[l008com]

Yeah it will be awesome when you can boot SSD on "regular" macbooks. As for my Mac Pro, I ordered a 1 TB HDD and 90 GB SSD last night. The SSD was on sale and has a rebate going.

[mduell]

If Apple had implemented ZFS a small (tens of gigs) flash drive could be useful as an L2ARC and ZIL.