Intel's Z68 Chipset and SSD Caching Reviewed

[iRobby]

I don't think so unless Apple has changed their approach to installing OS X on new iMacs since last year. When I bought mine (with SSD + HDD) the whole OS came installed on the SSD. Then, I had to figure out how to leave certain things on the SSD and store other things on the HDD. Ultimately I decided to simply store the whole "Home" folder on the HDD.

yes that is how Apple did it like the previous poster said . Apple puts ALL pre-installed applications including the OS on the SSD and lets you keep file storage. on the HDD.
My questions is since i'm buying both on my iMac after I purchase the iMac how do I install future applications on the SSD myself. I prefer to keep all my applications on the SSD. Is this done by default when you install CD-ROM based or web download applications? or do I need to manually place them in the SDD upon installing?

Also, if you do purchase the SSD only option from Apple doesn't that by default do SSD caching since there is no other drive?

 

[daneoni]

^
No. Apple doesn't currently support SSD caching period. It's not enabled in the OS. So it would be a basic/pure SSD in a mac.

 

[iRobby]

^
No. Apple doesn't currently support SSD caching period. It's not enabled in the OS. So it would be a basic/pure SSD in a mac.

Then how does the computer cache in SSD only iMacs? games and other applications I use have cache files and due to my dinosaur of a PC at the moment I constantly have to empty the caches. So wouldn't the SSD cache those programs?

 

[LarryC]

Deleted.

 

[HobeSoundDarryl]

I don't know that I'd call that a variation, it's really a different animal. Doing that will speed up boot and application launch, but the caching method has the potential to speed up any loading on the machine, which has the potential to provide much bigger speed gains. Wear and tear on the SSD is an issue, although that is lessened if they have a smart algorithm that puts more emphasis on caching most often used data and not writing everything that is loaded from HD.

That's going to be a very smart algorithm to be able to determine what is more important and what is less. I'm perceiving that it's going to work more like a big ram cache storing ALL of the most recent file activity with a "dumb" assumption that stuff you've used recently, you'll probably want to use again soon and stuff you haven't used recently, you'll probably NOT want to use again soon. Else, it's going to have to be able to judge mundane stuff like which website files should be cached and which should not, which iTunes file should be cached and which should not, and so on.

I'm also not so sure about the "bigger speed gains". In my own situation, big files (like applications) are permanently stored on the SSD and thus immediately available at being loaded into memory at full SSD speeds. Meanwhile little files like images & text in web pages I visit, doc files, music files, etc are loaded from the HDD. Sure, if those little files were also stored on the SSD, they would make it into memory faster than they would from the HDD, but they are so small, they are available to use really fast as loaded from the HDD too.

More simply, a fat application file on the SSD does load crazy fast compared to the same app loaded from the HDD. Bootup with those OS X files on the SSD is much faster than booting up via HDD too. BUT, as the files to be loaded become smaller, it's harder to notice any delay. Mathematically, a song in iTunes will get into memory faster from the SSD (or one of these cache SSDs (if I played the song recently enough) but perceptually, if the small song file is loaded from the HDD, there is not a noticeable delay that actually wastes my time.

Go very far down the alternative path and there would be no justifying an HDD vs. an SSD as one could argue everything should be on the SSD because every load will save some time. While true, that's also where you have to factor in cost of big HDD storage vs. equivalent SSD storage and the (too many) file writes problem of the SSD. Especially related to using one as a cache (for presumably all recently changed files to keep them nearly immediately available), I would think this would just use them up much faster than how I'm using the one that came with my iMac.

I love the idea of a fast cache. I just wonder about how fast such a solution would wear out without some super-intelligent algorithm to somewhat magically know what to keep on hand and what to ignore.

 

[DocNYz]

yes that is how Apple did it like the previous poster said . Apple puts ALL pre-installed applications including the OS on the SSD and lets you keep file storage. on the HDD.
My questions is since i'm buying both on my iMac after I purchase the iMac how do I install future applications on the SSD myself. I prefer to keep all my applications on the SSD. Is this done by default when you install CD-ROM based or web download applications? or do I need to manually place them in the SDD upon installing?

Also, if you do purchase the SSD only option from Apple doesn't that by default do SSD caching since there is no other drive?

Yeah if it's your boot drive (startup disk) most of the time it will automatically install everything on the SSD. It's actually more seamless than I expected once you get it working. It's a good idea to check though during the install process, and if for some reason it's selected your HDD instead of the SSD, just click on the SSD and you're good to go!

 

[HobeSoundDarryl]

yes that is how Apple did it like the previous poster said . Apple puts ALL pre-installed applications including the OS on the SSD and lets you keep file storage. on the HDD.
My questions is since i'm buying both on my iMac after I purchase the iMac how do I install future applications on the SSD myself. I prefer to keep all my applications on the SSD. Is this done by default when you install CD-ROM based or web download applications? or do I need to manually place them in the SDD upon installing?

Automatic. Where your applications folder is stored is where future applications will be stored. For example, in my set up the Applications folder stayed on the SSD as installed by Apple (I only moved my Home folder to the HDD). Since then, every new application I've installed and all updates to existing applications are stored in that same Applications folder (on the SSD). I'm good with this as this amounts to only occasional writes to the SSD, so it is mostly used as "read" storage.

Also, if you do purchase the SSD only option from Apple doesn't that by default do SSD caching since there is no other drive?

If you only have a SSD drive, all of your reads & writes will be on that SSD. I suppose you could say it's one entire "cache" drive. You might also be able to call it one big "ram" drive or "memory" drive too. My perception of that kind of setup is that it is going to prove to be a more expensive arrangement as the SSD will wear out sooner (presumably) than the same computer with a hard drive would wear out the HDD. Thus, if I went that way, I would do so knowing I'll probably have to replace that SSD before I would have to replace the same setup with an HDD. Then, I would hope that the pricing for SSDs drop fast enough to not make that a big deal when that time comes.

I think some here see Macs as having to be upgraded every year or two at most, so this problem will probably be passed on to someone else (the buyer of their old- but not really so old- mac) before it hits their own pocketbook. But if you buy for the longer run, or you are a heavy user of the computer, all I've read about this topic says to set aside the dollars for a new SSD which will be needed sooner than an HDD would wear out.

 

[Piggie]

Good to know, but I'd rather go full SSD. After using computers with it I can't go back. Just like the MBA, I wish those kind of options would come across to other Macs as well.

Yes, everyone would, but we can't all afford a 2TB SSD.

Until a 2TB SSD is a reasonable price (when do you retire!) then a smaller SSD as a cache and a BIG HDD for storage gives users the best and most practical alternative.

I hope Apple does not screw their own customers this time and say HDD or SDD only and does implement this, with the Max 64GB of SSD which is reasonable enough to fit in most high end iMacs as standard.

 

[iRobby]

Automatic. Where your applications folder is stored is where future applications will be stored. For example, in my set up the Applications folder stayed on the SSD as installed by Apple (I only moved my Home folder to the HDD). Since then, every new application I've installed and all updates to existing applications are stored in that same Applications folder (on the SSD). I'm good with this as this amounts to only occasional writes to the SSD, so it is mostly used as "read" storage.

Thank you that was my understanding. Which is why I want both. I want the performance of the SSD for my application programs and the files such as documents, music and photos on the HDD. That is what takes up the most space applications usually do not. So I want the SDD for the applications performance benefit and the 1TB HDD for storage .

It'll just get some used to installing or downloading certain things in the right drive since I've always had one. I'm sure it'll become 2nd nature though.

thanks again!

EDIT: oh a iMac newbie question: what is the home folder that you did move? what is it's purpose . What was the benefit of moving it to the HDD?

 

[blue22]

Some and arguably newer MBPs have a SATA III optical port

This is the big debate within the 2011 MBP community. Apple system profilier is showing SATA III for some and not for others. Do all the MBP have SATA III in the drive bay that would easily be activated through a firmware update, I hope so. With it being that fragmented I doubt Apple will enable SSD caching through OSX for the 2011 MBP's for this very reason. Might need to be hacked which could lead to other issues.

If that is true about some MBP's having an optical port of SATA II vs. SATA III, does that discrepancy have anything to do with the Intel chipset delay/problems they announced back in January? If so, then do the more recently shipped/manufactured 2011 MBP's have SATA III in them, yes? Also, has Apple made any official acknowledgement of this?

Thanks in advance!

 

[FuNGi]

Thanks for this info. I had overlooked (or fogotten) the news of Seagate's "On HDD" solution, which I can see as an easy-for-hardware-vendors to implement without having to do much other work (and which also is of benefit to home DIY'ers to refit legacy hardware).

In general, I personally have seen the lack of SSD caching as a longstanding hardware shortfall that Apple should have changed two years ago, given that they're selling "we don't know how to make cheap junk" premium hardware.

The "SSD Sticks" in the current MBAir design were IMO a very welcome sight to see ... even though I know that the MBA is all SSD-based now, I thought that Apple had finally had woken up to an approach for a relatively "cheap" SSD-based hardware speed improvement ... and of course, to see the new iMac now come out without having that interface was not the case, and IMO a disappointing step backwards in the form of "Opportunity Lost".

In looking at AnandTech's page, it appears that the Intel Z68 chip is really for reducing dependencies on clock timings (ie, it makes overclocking easier for harwdware developers), and the SSD caching feature almost seems to be a secondary thought that was thrown in.

As such, I don't see this as a huge piece of 'good news', other than it appears that in doing some of this, Intel now has the published data to inform hardware developers that they dont need a huge (=expensive) SSD to get the basic performance gains: they only need ~64GB (and the faster it is, the better).

Personally, I'd love to see the MBA's "SSD Sticks" design be proliforated across all of Apple's product line - - their size & form factor should make them be as easy of an upgrade as RAM, and should offer a nice boost at very low relative cost (another Apple Store Option, too) ... particularly if it starts with lower-end models with a ~16GB stick instead of a $100 64GB one, we're probably looking at an easy 5% boost for only $25 or so.

-hh

Yeah, I've got Seagate's on HDD 4GB SSD solution running in my 2008 unibody MBP. It was part of my 'upgrade' along with 8GB of RAM. The two additions have seemed to boost the overall speeds of my workflow. I too am surprised that other vendors haven't adopted this seemingly easy solution along with slightly larger SSD 'caches' of 16GB or so to incorporate more 'working' or 'recently used' files.

 

[profets]

Yes, everyone would, but we can't all afford a 2TB SSD.

Until a 2TB SSD is a reasonable price (when do you retire!) then a smaller SSD as a cache and a BIG HDD for storage gives users the best and most practical alternative.

I hope Apple does not screw their own customers this time and say HDD or SDD only and does implement this, with the Max 64GB of SSD which is reasonable enough to fit in most high end iMacs as standard.

Lol, a 2TB SSD? I never said that. I was talking about 64GB or more for system, OS, applications, etc.. Data/media/docs/etc doesn't need to be siting on an SSD.

When they talk about 64GB max for the hybrid purpose, then I'd say who cares? At 64GB or more, I'd rather use the SSD as the system disk, not just for some hybrid/cache use.

 

[drsmithy]

Edit: You can also get a 32Gb flash drive for just $50 so why $110 for the 20GB SSD? For that much you can get a 64 Gig flash drive It's the same tech

Because the flash memory in USB thumb drives has horrendously poor performance, particularly for writes.

That's because the drives you've been using aren't Single Level Cell (SLC). They're the cheaper but less reliable Multi Level Cell or MLC. MLC drives have a limit of about 5000 erase/write cycles per block, whereas SLC is about 100,000. For a caching drive or one that will be written to frequently, SLC is important to prevent the drive dying prematurely. The problem with SLC, is it's extremely expensive for the same size drive.

More important than SSD longevity, which is already comparable to mechanical drives even for low-end MLC SSDs, is that SLC flash is much, much faster for writes, particularly small random writes.

That's going to be a very smart algorithm to be able to determine what is more important and what is less.

That's presumably why it plugs into the OS via a driver, so it can leverage the OS's "inside view" on what data is best cached, and what is not (eg: generally speaking you don't want to cache long sequential reads).

If it can interact with the OS, this system should work just like the OS's own RAM cache, only with less performance and greater space. It is the perfect use of SSDs given current technology levels, IMHO, and I'm surprised it's taken this long to appear in the mainstream.

 

[kingtj]

Question on Apple's implementation?

I guess from what I'm reading, the new iMacs with the SSD/HDD combo from Apple are configuring things so the SSD contains OS X, the Applications folder, AND the home folders too? Or did they redirect the home directory to the HDD?

Curious, because after I added a new SSD as my boot drive in my Mac Pro, I found that one of the largest users of disk space was my home directory. (By default, all the iTunes media winds up in there as well as the iPhoto or Aperture photo libraries, and Steam puts all of its cache files for downloaded games in there too.)

I followed some advice to redirect my home folder to the HDD via advanced settings in the Preferences -- but was also told that Apple never officially sanctioned redirection of the Home folder(s), due to potential incompatibilities with various software apps.

Seems like they need to address/fix that and make it officially ok to do, with the rising popularity of SSD boot drives, which often only have 128GB or even 80GB of space.

 

[milo]

There has been a fair amount of discussion about SSD for a boot drive versus for a cache, but nobody has mentioned the third possibility. It seems like either two SSD (64 each?) or say a 128 with 64 for the boot partition and 64 to cache a data HD would have the potential to give the benefits of both while still being vastly cheaper than trying to put everything on HD.

That's going to be a very smart algorithm to be able to determine what is more important and what is less. I'm perceiving that it's going to work more like a big ram cache storing ALL of the most recent file activity with a "dumb" assumption that stuff you've used recently, you'll probably want to use again soon and stuff you haven't used recently, you'll probably NOT want to use again soon. Else, it's going to have to be able to judge mundane stuff like which website files should be cached and which should not, which iTunes file should be cached and which should not, and so on.

There are some details about that in the review, they cache based on frequently accessed data instead of just caching the most recently used data, as well as other criteria. And with an SSD boot drive you're going to going to have a lot of wear and tear as well - if the cached drive is doing more reading than writing (which would be the case in my situation), that will also keep wear and tear down compared with SSD boot drive.

I'm also not so sure about the "bigger speed gains". In my own situation, big files (like applications) are permanently stored on the SSD and thus immediately available at being loaded into memory at full SSD speeds.

People don't all work the way you do, some have files on the data drive that would benefit from the caching. Which is why I said it has the potential to provide big speed gains, not that it would necessarily be better for everyone. Also keep in mind that if you have an SSD boot drive, you may have a fair amount of data on that drive that you rarely or never use yet it's still eating up that expensive SSD space.

Along with allowing SSD cache bigger than 64 gigs, the one other thing I'd like to see is an option to have it cache reads only and not cache writes at all. For the work I do I need the speed on reads but faster writes would make little if any difference.

 

[daneoni]

Then how does the computer cache in SSD only iMacs? games and other applications I use have cache files and due to my dinosaur of a PC at the moment I constantly have to empty the caches. So wouldn't the SSD cache those programs?

There is no SSD Caching in OS X period. Regardless of hardware as far as i'm aware. Everything the OS/apps reads/write will be done on the SSD just as it would if it were an HDD only iMac. If you have a hybrid then since the OS/Apps are on the SSD any file they read/write (unless otherwise told so) will be done there.

If that is true about some MBP's having an optical port of SATA II vs. SATA III, does that discrepancy have anything to do with the Intel chipset delay/problems they announced back in January? If so, then do the more recently shipped/manufactured 2011 MBP's have SATA III in them, yes? Also, has Apple made any official acknowledgement of this?

Thanks in advance!

Nope Apple have been using the revised chipset from the get go they just seem to have decided to start using the second SATA III port in random/recent builds of the MBP. I guess it's down to which factory your machine is assembled from. Some who bought as recently as last week April still have SATA II optical ports whilst some who bought back in Feb got both SATA III ports.

 

[johnfkitchen]

... Heck, I wish they didn't have the 64 gig limit, for certain applications there will probably be benefit with even larger SSD.

The 64GB limit is probably based on the physical size of the memory that contains metadata describing the LBA accesses.

The Anandtech article described the implementation this way:-

"Intel's SRT functions like an actual cache. Rather than caching individual files, Intel focuses on frequently accessed LBAs (logical block addresses). Read a block enough times or write to it enough times and those accesses will get pulled into the SSD cache until it's full. When full, the least recently used data gets evicted making room for new data."

A history of LBA accesses needs to be kept to prioritize LBAs for promotion to SSD from HDD. My guess is that they have enough space to describe the most active 64GBs, but not the full size of the HDD. There's a lot of LBAs in a 3TB drive

 

[Malcolm.]

I've got a late 2006 iMac that is fine for what I use it for, but the video card is failing at even warm temperatures and I am prone to Windows-like lockups lately.

I like how everything that goes wrong on PCs is automatically the fault of Windows. Hardware issues can affect any and every system, through no fault of the OS.

 

[milo]

The 64GB limit is probably based on the physical size of the memory that contains metadata describing the LBA accesses.

Interesting idea, but the articles say Intel tested bigger ones but didn't see much more improvement. Why would I like to see bigger even though Intel didn't see the benefit? Because my usage would likely be completely different than what Intel tested.

 

[Elijahg]

At $2000+ per terabyte? That would be wildly expensive and impractical for my usage (which I'll readily admit is very different than mainstream usage, but it would still make sense for intel to make the technology as flexible as they can). But caching like this with a 128 or 256 in the $250-500 range would be perfect.

Here are the specific criteria:
1 Huge amount of data on HD (way to expensive to put it all on SSD)
2 Only a small portion of that data is used on a regular basis
3 Extremely difficult if not impossible to manually grab that small portion and copy it to SSD

This technology is perfect for handling that at low cost although removing the limit of 64 gigs would make it even more useful.

So you constantly change the same ~150gb portion of some 300gb+ file over and over? As that's the only way you'd see any benefit of this tech. If you keep accessing random parts of the 300gb file such as with video editing, you won't see much performance boost, as the cached data will keep being fetched and replaced from the HDD. Or perhaps you have a huge database with some parts accessed constantly, and other parts not so often? You could have two databases, one on the SSD for fast/constant access, and another on a HDD for slower/infrequent access. Then you could be sure that the part of the database you need to access quickly is definitely on the SSD, and won't need to be re-read and re-cached.

More important than SSD longevity, which is already comparable to mechanical drives even for low-end MLC SSDs, is that SLC flash is much, much faster for writes, particularly small random writes.

It's true that SLC is faster than MLC, as it can erase a block each time instead of a whole page. However, a single block on a mechanical hard drive has a virtually unlimited number of writes, whereas even SLC SSDs start becoming unreliable at 100,000 writes. If you're only ever reading from a SSD, and barely ever writing, it'll last virtually forever. If you write say 100gb per day, a SSD won't last long at all, and a mechanical drive will certainly outlive it.

 

[Hellhammer]

It's true that SLC is faster than MLC, as it can erase a block each time instead of a whole page. However, a single block on a mechanical hard drive has a virtually unlimited number of writes, whereas even SLC SSDs start becoming unreliable at 100,000 writes. If you're only ever reading from a SSD, and barely ever writing, it'll last virtually forever. If you write say 100gb per day, a SSD won't last long at all, and a mechanical drive will certainly outlive it.

Hard drives have moving parts so sooner than later they will wear out. If you have a 120GB SLC SSD and you write 100GB a day, it will last for 120 000 days, which is equal to 329 years. Write 1TB a day and it will still last for 33 years. However, NANDs lose their charge after about 10 years so that will happen before you wear the NANDs out by writing.

 

[leetlamer]

The reason the 20GB SSD is so expensive is that it uses high quality SLC flash which is extremely durable and has faster write speed, as opposed to the cheaper MLC flash which is in most larger capacity drives.

I'm very confident that this feature will be in the next MacBook Pros, when I think Apple will get rid of the optical drive.

I posted about this back in February:
https://forums.macrumors.com/threads/1105663/

 

[drsmithy]

It's true that SLC is faster than MLC, as it can erase a block each time instead of a whole page. However, a single block on a mechanical hard drive has a virtually unlimited number of writes, whereas even SLC SSDs start becoming unreliable at 100,000 writes. If you're only ever reading from a SSD, and barely ever writing, it'll last virtually forever. If you write say 100gb per day, a SSD won't last long at all, and a mechanical drive will certainly outlive it.

So, assume 100GB per day of writes (a phenomenal amount of data in the context of this discussion).

Every day your 20GB drive will be completely overwritten 5 times.

100,000/5 = 20,000 days.

20,000 days is just under 55 years.

Even if that's off by an order of magnitude, an SSD will still last over 5 years, well into the time period when mechanical drives start to fail (and when a mechanical drive fails, your data is almost always gone - when an SSD can't write any more, your data is still available).

All else being equal, an SSD will _vastly_ outlive a mechanical drive, outside of corner cases involving massive amounts of data being constantly written.

 

[HobeSoundDarryl]

EDIT: oh a iMac newbie question: what is the home folder that you did move? what is it's purpose . What was the benefit of moving it to the HDD?

The home folder might be thought of as a master, personal workspace. It's where lots of the data you use will be stored. For example, home has folders like "movies" for (imovie) movies and movie files, "music" for iTunes music files, garage band files etc., "documents" for all document files like Word or Pages docs, "pictures" for your photo collection in iPhoto, "library" for all of the supporting files that makes all of the unique elements in the above (and much more) work to your own particular tastes, etc.

The home folder has lots of directories that get regularly written to by the operating system and application files. This is especially true of directories within "library" where lots of "cache" files are used. For example, every website you browse in Safari will involve file downloads of images, etc as your browsing history builds out. The Safari cache is in "Library" as are lots of other files that regularly get written to and updated in even casual use of your computer.

That's why I chose a non-optimal option of just putting the whole "home" folder on the HDD while leaving "Applications" and similar (files that don't need to be written to very often) on the SSD. The optimal choice would have been to carefully document which directories get a lot of writes and which get few to none and putting the latter on the relatively abundant space available on the Apple SSD option. But, in the end, I just did it this way because it was 1) easy, 2) fit my objective (regular write files on the HDD, mostly read files on the SSD) and 3) resulted in bootup and the big (and small) application files opening quick from the SSD while little files like photos, music, etc all automatically land on the HDD. That setup has worked very well for nearly a year now, yielding SSD fast where I expected it without much worry about wearing out the SSD too quickly.

 

[Shop]

I think this technology is too late in the game. It should have been developed about 10 years ago, and maybe would have had a massive consumer impact 5 years ago. Today the consumer can already afford a suitable size SSD, leaving mass storage for NAS or just using "the cloud".