Why a Fusion Drive si better than a 256Gb SSD (personal opinion)

[aevan]

Warning: a long read. Sorry, but this was building up for days and I just had to write everything on my mind.

There has been a lot of talk on the subject of SSD vs Fusion drive on these forums, and having read most of them, I decided to give my thoughts on the matter and perhaps help people that have dilemmas. Now, please note that everything here is my personal opinion and while I do try to base it on facts, it is what it is and nothing more. I am well aware that a lot of people will disagree with my views, but I also think people constantly get bad advice by reading these forums. I write this in order to try and help people make up their own mind. And, honestly, I strongly believe the anti-Fusion crowd here are giving some bad advice.

First of all, there is no denying that SSDs are awesome. They are also the future. In fact, a SSD upgrade is the single most dramatic speed upgrade you can get for any computer. They are also silent, durable and produce little heat. However, they also cost more. So, what is the solution to this problem - you guessed it, Apple’s Fusion Drive.

Now, we all know what the Fusion Drive is. It is, basically a smart software/hardware solution that ties up a very fast 128Gb PCIe SSD with a 1/2/3Tb HDD. It works beautifuly, and it’s better than a pure 256Gb SSD for most people, and I’ll tell you why.

I used to have an iMac with a 128Gb thunderbolt SSD drive and a 1Tb HDD. It was way way better than just with a HDD. I put my OS and all my apps on the SSD. Today, I have mostly the same apps I had then. As I am an illustrator and I have Photoshop (in fact, I have two versions CC and CC 2014 installed because some plugins don’t work with the new one), Adobe Illustrator, Corel Painter trial, Sketchbook Pro, Mischief and Zbrush installed. Other than that I have iWorks apps, the new Microsoft Office preview, as well as tons of small apps. I love apps and bought hundreds of dollars worth of them. Now, you may have much more apps then me, but I think it’s safe to say that the average user doesn’t have more. In fact, many people have way less. I just checked the size of my applications folder - it is 24Gb. Yup, 24Gb! Go and check your app folder. Seriously, go and check, I’ll wait. I can’t imagine that many of you have much more. I installed all the apps I work with, I installed a lot of apps I don’t need. I installed everything I could think of, to be honest. And it’s 24Gb. But just to make this more fun, let’s double that! Let’s say I have 50Gb worth of apps! Now, the OSX takes less than 10Gb, so let’s round that all up to an even 60Gb for OSX plus all the apps I could ever need. Now, I have about 30Gb worth of PSD files, AI files, jpegs, etc. These are not only my active projects, but also a lot of the older ones. I have my archive on a backup disk, but I really don’t need more than 15Gb work space for my illustrations (and the fact I have 30 is because I’m too lazy to manage that). That is 90Gb total. That leaves around 30Gb free on my SSD (And remember, for this ‘test’ I actually doubled my app space. In reality I always had somewhere between 45-50Gb free space on my SSD drive) . I originally planned to get a 256Gb one but decided I don’t really need it. You see, for everything else - movies, music, books, comics, etc. - I have the HDD drive. In fact, the HDD speed is quite fine for opening files. I worked with some very large (300-400Mb) PSD files from the HDD and, honestly, opening them didn’t take much longer than on a SSD (saving them took a bit longer, but nothing drastic). The truth is - if you have the OS and the apps on your SSD, you’re fine. And for me, there was plenty enough space for the work files too! So, as you see, 128Gb is quite enough - there is a reason there are perfectly fine MacBook Pros with 128Gb drives. Sure, there is an exception - there are some people that work with very very large uncompressed video and audio files, they also use RAID SSD drives and lots of RAM, etc. But that is a very specific use case. I honestly doubt most people have such requirements, even if they think they do while shopping for new gear.

Now, when the time came to get a new iMac, I decided to get the Retina iMac 5K and I decided to take the Fusion Drive option. As I said, I realised I don’t need more than 128Gb of SSD space, so my plan was to get the FD and then manually split it to a SSD and HDD parts and just mirror my situation from the previous iMac. To my surprise - this was completely unnecessary. Apple uses some really clever tricks to manage your files for you. They use write buffers for files under 4Gb, they also move files in 128Kb blocks (they don’t actually copy entire files back and forth, they are much more granular). The result is - my apps and os still run as fast as they did on a pure SSD, but the system also uses that ~50Gb of free space I had on my previous setup to speed EVERYTHING up. In fact, that space was going to waste while I did things manually. But just as OS manages RAM, now it manages your fast drive storage and does it really really well.

Now compare that to a 256Gb SSD setup you can get. First of all, yes, it costs the same, but you have to buy (often expensive) external thunderbolt drives. Second, you have more cables sticking out of your iMac and less free ports (not really a problem, but it’s still a downside). Third - and most important - you’re actually wasting space. You’ll probably put everything that would benefit from a SSD to the SSD drive and have more than 100Gb of SSD storage free. What do you put there? Movies? Music? Documents? In my case, yes, there is objectively less SSD free space, but it is used much more efficiently, as it is system managed. The music I listen to the most is most likely on the SSD portion of my FD. And my favorite TV show. In reality, I would have never bothered to move these manually to a 256Gb SSD (no one would). In fact, I’m betting that in practical terms, I’m using my SSD portion on a FD more than most people are using their 256Gb SSDs. Not that it even matters, because - as I said - there really is no big difference between opening a movie from a SSD or a HDD, but there you go.

Of course, if you can afford a 512Gb or 1Tb SSD, that’s a no brainer. Sure they are better. Then everything you have is on a SSD and it’s great. It also costs a lot more. But the FD offers roughly the same performance as that for a fraction of the price.

Now, there are reasons to go full SSD. Some professionals need a high-speed storage solution across the drive. Some people just have enough money so they are willing to pay premium. That is all ok. But when someone comes asking for advice, obviously they are asking because they want to get the most out of their money (otherwise they’d just buy the most expensive option without asking). And I read time and time again how people say they should go for a pure SSD, even if it means going just 256Gb.

So, there you go. With all this in mind, I recommend to everyone who doesn’t already plan on getting some good external space (there are some valid reasons to have external drives) to go for a Fusion Drive. It's great. I don't have experience with the previous generations of it, but the latest PCIe one works really well.

Also, please ignore all those remarks about noise, heat and reliability. I’m surprised that a lot of people here would rather invest in a pure SSD than AppleCare, for example. Look, we had HDDs for decades. And here people are acting like they are about to fail any minute. Noise? I don’t hear my FD. Ever. I tried, ear to the computer and all. And finally - heat - it’s a couple of degrees warmer.

To end this really long post - here is my take on the 256Gb SSD vs Fusion Drive. For most people, Fusion Drive is the better option. There is a reason Apple made that, and not the 256Gb drive a default option, although they cost roughly the same.

If you disagree, do me the courtesy of explaining why, instead of just saying something like "You're wrong. FD will break and you will loose your files. SSD is the future, and FD is just marketing. Go SSD, you won't be sorry."

Hope this helps and enjoy your purchase, whatever it is.

 

[maflynn]

If you don't need the space, then SSD is better, if you need more space and your budget does not allow for the purchase of a larger SSD, then a Fusion drive makes more sense.

 

[aevan]

If you don't need the space, then SSD is better, if you need more space and your budget does not allow for the purchase of a larger SSD, then a Fusion drive makes more sense.

As I tried to point out in my text, if you don't need the space, a 1Tb FD will actually serve you the same as a 256Gb SSD. Because when you do need the space (for media) - you need more than 256Gb. And when you don't, 128Gb is just as fine, so why not get a 1Tb HDD with that?

Of course, this is for desktop computers. For laptops - SSD all the way. Smaller, more resistant to moving around, less power consumption, and they go against 5400rpm laptop drives.

 

[maflynn]

As I tried to point out in my text, if you don't need the space, a 1Tb FD will actually serve you the same as a 256Gb SSD.

No it won't, SSDs are faster better then a combined SSD/hard drive combination.

When data is off loaded to the hard drive, access speeds will decrease.

I don't think its rocket surgery, to see how a single digital solution, is superior to a merged digital/mechanical solution. If I have no need for 1TB of storage, there's no need to get a fusion drive. The SSD will be better.

 

[aevan]

No it won't, SSDs are faster better then a combined SSD/hard drive combination.

When data is off loaded to the hard drive, access speeds will decrease.

I don't think its rocket surgery, to see how a single digital solution, is superior to a merged digital/mechanical solution. If I have no need for 1TB of storage, there's no need to get a fusion drive. The SSD will be better.

Marginally better in practical terms. I just love the theoretical talk like that "a single digital solution vs a merged digital/mechanical solution". No, the FD will work equally good - all you important stuff where you actually see the difference (OS and apps) will be on the "digital solution", and you get storage space as an extra. I don't notice the difference between my PCIe SSD-only MacBook and the Fusion Drive. I just don't. Perhaps I can measure it, but I sure can't feel it. So, please, don't give me the empty tech vernacular. I'm talking about real life usage here.

 

[Moonjumper]

Marginally better in practical terms. I just love the theoretical talk like that "a single digital solution vs a merged digital/mechanical solution". No, the FD will work equally good - all you important stuff where you actually see the difference (OS and apps) will be on the "digital solution", and you get storage space as an extra. I don't notice the difference between my PCIe SSD-only MacBook and the Fusion Drive. I just don't. Perhaps I can measure it, but I sure can't feel it. So, please, don't give me the empty tech vernacular. I'm talking about real life usage here.

Your real life usage is not the same as real life usage for someone else. an FD will work equally as good for some, but not others.

I would chose SSD not for the difference in speed, but because of noise (I did notice the difference when going HDD to SSD) and reliability (1 thing to go wrong instead of 2, I had the HDD replaced in my last iMac due to a failure).

 

[aevan]

Your real life usage is not the same as real life usage for someone else. an FD will work equally as good for some, but not others.

I would chose SSD not for the difference in speed, but because of noise (I did notice the difference when going HDD to SSD) and reliability (1 thing to go wrong instead of 2, I had the HDD replaced in my last iMac due to a failure).

Certainly, I'm just talking about my usage scenarios.

But that's just it - you can't go and recommend something universally. I tried to explain my usage case so people who recognize similar needs may get some advice. In fact, I'd wager that my usage case is more common to people than the one that specifically requires a SSD (and they do exist, I agree).

For the most part, I feel as if people are justifying their purchases rather than having actual experience or thinking things through.

As for noise, I honestly can't hear my FD. Like, ever. But, perhaps your hearing is better. Or you somehow had a louder drive. As for reliability, that is more of a hypothetical reason, really. Things fail from time to time, but basing your buying decisions on some idea that a certain tested and proven technology might fail because it is comprised of "two things" is wrong. Everything in a FD has been around for a long time, it's tested and reliable - and true, it might fail, just as a pure SSD might fail. It happens, so back things up. But, I wouldn't worry about things failing (if I did, I wouldn't buy an iMac in the first place, I would've gotten a far more repairable PC instead). As I said, this sounds more like rationalizing things after a purchase. Fusion Drives are reliable, don't worry about it. And are a better choice for most (not all) people than 256Gb SSD. In my opinion, of course, and everyone is entitled to form their own.

 

[JustMartin]

I've said similar things in previous posts. In one thread I asked people to actually explain why they needed their SSDs from a speed point of view. I was genuinely curious. The only person to reply was yichua5 who is doing extremely heavy rendering and video work.

You make a good point about the combination of internal SSD and external hard disks. People are basically managing their own caching - probably not that efficiently and it takes time. Fusion drives do that caching automatically for you (I can't understand people who split their drives because they don't think the software can manage the caching properly).

 

[Cape Dave]

SSD all the way baby! Anything else is not as reliable or fast. PERIOD. END OF STORY. YOUR WITNESS.

 

[matreya]

SSD all the way baby! Anything else is not as reliable or fast. PERIOD. END OF STORY. YOUR WITNESS.

I agree with this. Fusion is there for people who MUST have more than 512GB of main drive storage but either cannot afford apple's premium for SSDs or needs the 3TB option.

After the stories about Seagate 3TBs, I wouldn't trust one inside my iMac in a fit.

 

[aevan]

I agree with this. Fusion is there for people who MUST have more than 512GB of main drive storage but either cannot afford apple's premium for SSDs or needs the 3TB option.

After the stories about Seagate 3TBs, I wouldn't trust one inside my iMac in a fit.

I am clearly talking about 256Gb SSD drives in this post. 512Gb and 1Tb SSD drives are great for those willing to pay more money and make a bit more sense than a 256Gb SSD in an iMac. For most people, it may actually be overkill, but if you can afford it, go ahead. This post is about 256Gb SSD vs 1Tb FD, as they cost the same.

----------

SSD all the way baby! Anything else is not as reliable or fast. PERIOD. END OF STORY. YOUR WITNESS.

Thanks for taking the time and effort to enrich this discussion, and my original post, with this argumented, insightful and detailed comment.

 

[Fishrrman]

Switching from the previous SATA connection to PCIe for the SSD portion of the fusion drive has been a game-changer.

PCIe offers about a 40-50% speed improvement over a SATA-connected 2.5" SSD.

I used to recommend a "split" SSD + HDD combination for those who needed the space, but lately fusion seems more practical.

Of course, one MUST maintain a FULLY BOOTABLE CLONED BACKUP if one chooses to use fusion internally. What happens if the SSD portion of the fusion drive fails? You won't be able to boot from the regular partition, and you won't be able to boot from the recovery partition, either (assuming that the RP is normally "stored" on the SSD).

What is missing from the Mac market at the moment is an app that gives the full range of control (and available commands) over a fusion drive setup. Disk Utility is woefully inadequate in this regard, and I sense Apple has chosen to hobble it this way on purpose.

It's time for the aftermarket to step up to the task.

 

[ApfelKuchen]

I agree with this. Fusion is there for people who MUST have more than 512GB of main drive storage but either cannot afford apple's premium for SSDs or needs the 3TB option.

After the stories about Seagate 3TBs, I wouldn't trust one inside my iMac in a fit.

Both 256 GB Flash and 1TB Fusion cost the same $200 BTO up-charge. So, the more accurate statement is "...for people who MUST have more than 256 GB of main drive storage..."

My bias? I have a 27" iMac with 3 TB FD, and don't regret the choice for a second. Even though the FDD is likely to fail before the Flash. Even though, if budget allowed, I'd have all-Flash.

But it's really hard to justify a 1:5 price difference for 1 TB of speedier storage ($200 extra for a 1 TB FD vs. $1000 for 1 TB Flash) when the performance difference is so slim. And as to reliability, I could replace that HDD two or three times for that $800 price differential (and that's using the services of a repair shop - I'm fully competent to DIY the repair).

Yep, every use case is different, but the OP is making the same arguments I've made (including trusting the OS to know how to manage the Flash with the same efficiency that it manages RAM).

It's pretty straightforward, really. If you have more than 128 GB of files in regular, active use, then there is going to be a speed hit every time files move between HDD and Flash. The magnitude of that hit depends upon the frequency of use of the off-Flash files/blocks. In my case, I'd wager there are relatively few HDD calls - my HDD is pretty much a musty old attic I'm too lazy to clean. And I'm also not willing to actively manage storage to maximize system speed when my computer is smart enough to do it for me.

Really, a lot of this argument could go away if Apple added some FD statistics to Activity Monitor. All we'd need is the equivalent of Swap Used. And separate numbers for Flash and HDD read/write activity. And a graph comparing Flash to HDD usage... priceless!

What happens if the SSD portion of the fusion drive fails? You won't be able to boot from the regular partition, and you won't be able to boot from the recovery partition, either (assuming that the RP is normally "stored" on the SSD).

Small quibble as to the recovery partition. First off, since recovery is infrequently accessed, it's probably on the HDD. But whether HDD or SSD fails... Internet Recovery will still be available unless you're off-grid.

 

[AppleFan360]

aevan - Good post. Quite frankly I tire of the SSD evangelists around here constantly telling others how to spend their money. You are right, having all SSD is awesome but not for everyone.

Another thing is that you own this beautiful iMac with a small footprint and very few wires. What do they tell you to do? Get a small SSD inside and start adding a bunch of wires and crap to the top (or under) your desk. Not my first choice.

Whenever these "SSD vs Fusion" threads pop up, I first get clear on whether or not the OP will want external drives, then I give the appropriate advice. SSD evangelists only know one answer and that's it!

 

[matreya]

aevan has a valid point that a 1TB Fusion drive is better value for money than a 256GB SSD, end of story.

Some of us are not fetishists wrt cables. I'd rather backup my system directly than rely on a wireless time capsule, for example.

I for one have more media files than could possibly fit on a 3TB fusion drive by several multiples, so I have Thunderbolt storage that runs faster than any other interface I've used in 30 years. That isn't everyone's usage case though.

Personally, I would rather have an SSD inside than some spinning rust made by a manufacturer with the single most wretched name in the storage industry.

 

[edjrwinnt]

I went with the Fusion drive with the theory that I would have a backup drive in case one of the two drives fails beyond the warranty period. Whether that will happen or not remains to be seen. I do not want to have to deal with external drives connected to the computer in order to use it.

 

[matreya]

I went with the Fusion drive with the theory that I would have a backup drive in case one of the two drives fails beyond the warranty period. Whether that will happen or not remains to be seen. I do not want to have to deal with external drives connected to the computer in order to use it.

Not having at least a Time Machine backup or clone of your system drive is a HUGE mistake.

 

[WilliamG]

This argument is really silly. SSD is better in every scenario except for price/capacity. I have a 3TB Fusion in my iMac, but I use a 1TB external Thunderbolt SSD as boot drive for OS X/Windows because it frustrated me so much using the 3TB Fusion. Random slow seeks are not fun at all.

 

[roadkill401]

But it's really hard to justify a 1:5 price difference for 1 TB of speedier storage ($200 extra for a 1 TB FD vs. $1000 for 1 TB Flash) when the performance difference is so slim.

The statement you made is actually wrong or at least very misleading. The two are not even remotely equal in performance.

The fusion as has been said many times is just a 128gb SSD + a HD mapped together inside some Apple magic. But the size of the SSD is still only 128gb and is not any larger. So the performance is actually limited to that 128gb. For most people, they will be very happy with this arrangement and it will give them a close to the same performance that they would get from a true SSD drive.

But there are some pitfalls that you must consider. The Mac decided what it feels are the most accessed and best to be in the faster SSD portion, not you! The access speed is limited by the decisions that your Mac has made and is not a constant for the span of drive space that you have.

For instance. You are working on your project and have itunes running in the background playing your favorite albums on repeat. As this is being accessed all the time, your block of music that really does not need to be high speed can get moved to the SSD as it's access count will shoot up.

However, you have a very large database file that is 32gb in size, but you only access it once a month. As your access count on this file will be very low as you don't use it all that much, it will reside purely inside the HD portion of your fusion drive and the load time for that large file will be much slower than your itunes music even though it might be much more beneficial for the two to be reversed for their location on the fusion.

Your music really does not need high speed access ever as itunes will start playing the song well before it is loaded and the difference between the seek time to get that first block loaded on an old technology HD be it local or even external on a USB1 connector, would be around 500ms. do you care if you wait 1/2 a second for your music to start? No. after that initial first block is loaded, it doesn't make a hoot of a difference how fast the rest of the data is loaded as your music is playing and the data is buffered well in advance of it's need.

The database however needs to be load into memory in chunks and read/write access time is very critical. Write's can be buffered but reads cannot. It all won't fit into your computers memory so the fastest drive access can be critical for getting the task done in the least amount of time. Here the Fusion can let you down as now it has to either move the data from the HD to the SSD in the background so you now have a mass of CPU I/O to deal with, or you are s.o.l. for fast disk access as your low priority file is now all of a sudden a large priority file.

A fusion drive banks on the fact that low priority files will stay as low priority files and as such can stay on the HD side of itself. But trying to give a limited system some smarts to know how you are working and what files you will need to be fast and what you really need to be slow is far beyond the science inside the machine. the best it can do is guess and hope that it is right based on what assumptions were made and if you fall outside of those, then you will be left behind.

 

[edjrwinnt]

Not having at least a Time Machine backup or clone of your system drive is a HUGE mistake.

I agree that is why I use my Mac server time machine backup service and I have Time Machine backup to my NAS. Plus, I have my Fusion drive partitioned with two equal partitions with the second partition cloned from the boot partition.

 

[aevan]

A fusion drive banks on the fact that low priority files will stay as low priority files and as such can stay on the HD side of itself. But trying to give a limited system some smarts to know how you are working and what files you will need to be fast and what you really need to be slow is far beyond the science inside the machine. the best it can do is guess and hope that it is right based on what assumptions were made and if you fall outside of those, then you will be left behind.

Look, no one is saying that the Fusion Drive is the same as an SSD. You just made one example where SSD is a better choice. But that's not fair - you specifically chose a situation where the Fusion Drive would fail. By that logic, one can justify pretty much anything. I could give you an example where anything less than 64Gb RAM is not enough. Does that mean that for most users, 8 or 16Gb won't be enough?

All I'm saying is that for most people, most of the time, a Fusion Drive is a better choice than a 256Gb SSD drive. You cannot disprove that by saying that for some people, some of the time, a pure SSD would be a better choice. Besides, if you need fast access to lot of large databases, a 256Gb SSD won't do much help either, as there isn't enough space.

For me, for my usage case? I barely see any difference. And I'm guessing that would be the case for a lot of people. Telling everyone to buy a 256Gb SSD + external Thunderbolt storage (which is the common advice on these forums) - is just NOT good advice.

 

[matreya]

Plus, I have my Fusion drive partitioned with two equal partitions with the second partition cloned from the boot partition.

Why would you do THAT??? Seriously, if either the SSD or HDD fail, you've lost both partitions... it's not a real backup...

If you really want a decent bootable clone of your Mac, get a Thunderbolt SSD and clone to that

 

[edjrwinnt]

Why would you do THAT??? Seriously, if either the SSD or HDD fail, you've lost both partitions... it's not a real backup...

If you really want a decent bootable clone of your Mac, get a Thunderbolt SSD and clone to that

Different strokes for different folks. I am still tweaking my setup and I like having a backup partition to boot from if I screw something up. I can also clone it back if I need to. I am using the beta version of 10.3 with a 5 lcd setup, including a Dell 4k lcd, and I am finally getting to the point where I am happy with my retina iMac.

 

[redheeler]

First the SSD. For those who do go with Fusion drive it would work just fine, but they can't expect it to be as fast as a 256 GB SSD depending on what data is on the HDD and what data is on the SSD. Even if they choose to de-fuse the Fusion drive they will still be stuck with a half as large 128 GB SSD which also has slightly slower read and slower still write speeds compared to the 256 GB.

Then there's the HDD. In an iMac with Fusion drive it is the most likely component to fail and very difficult to replace if more capacity is desired. External storage can be swapped or added at any time and easily replaced if it fails.

For these reasons I can't recommend Fusion drive over 256 GB SSD with external storage to someone who isn't on a fixed budget. To me it's just too much of a sacrifice for saving the cost of cheap USB 3 external storage.

 

[andy9l]

I'm a bit confused about this thread and the first post. The title says the Fusion Drive is better, but the OPs entire argument is based on (almost) never using the spinning drive. Therefore suggesting a 256GB SSD is 'always' the better option, given it costs a premium of...$0.

The best iMac storage performance available now is pure SSD (1TB if possible) with external thunderbolt SSDs if needed. This is expensive. The cost compromise is vastly slower Fusion Drives, but the cost is vastly lower too.

Reasons for a Fusion Drive:

1. Budget
2. Distaste in faster external storage
3. See 1.