Case For Unfusing the Fusion Drive

[maflynn]

Well, my experiment with a split up Fusion drive is over. I found not only the work effort not to be worth it, but the overall management was increased to a point that I felt the downsides outweigh the benefits.

I know everyone's situation is different and my setup and needs is different, so while this may not work for me, it may for others.
My issues is how much space I have for my home folder. I touched upon how much my Library folder consumes, but I don't think I mentioned the other folders. Here's the latest screen grab of my space usage:


I'd basically need to either create all sorts of symlnks, modify iTunes and/or move my home folder to the spinning hard drive (and lose some of the benefits of the SSD's performance). My needs are such that I have more data then what could fit on the SSD. Admittedly the contents of the Pictures folder could be moved, but that means a lot of work to reconfigure Lightroom to point to the correct location. Its easy enough to repoint iTunes to another drive, but in my experience that resets itself back to the home user folder.

The point I'm trying to bring up, is the simplicity and elegance of the Fusion drive cannot be overstated. I'm now able to work seamlessly without managing where my data ought to go.

I'm not against splitting up the Fusion drive, I think there are some advantages but at least in my latest go around, I felt those advantages didn't over come the disadvantages. I may circle back on this in the future, but for now, I'm content with letting Fusion handle the data moves.

As I understand it an SSD's life span is determined by the max number of writes made to it, in other words, each write made to the SSD is one step closer to its death until it reaches its peak write number, and the thing just dies.

I've been told that number is theoretically high, that it shouldn't be a concern. I have a 2012 rMBP that still seems to be going strong, even though its being used almost daily

 

[crouchingtiger]

OK, I am not going to worry about the maximum number of writes to an SSD which in practice is completely irrelevant to 99% of people. What I do like is the fact that when I'm doing my photo or movie editing, everything is nice and responsive because I am always taking advantage of SSD speeds on the write cycles (e.g. saving my work)

I mean, to each their own, but isn't the point of having the fast hardware to use it? Fusion Drive works beautifully to ensure that over the long haul I am using the SSD to its max potential without compromising data storage capacity.

Another hidden disadvantage to Fusion drive is that as the above post states, everything is written to the SSD first.

As I understand it an SSD's life span is determined by the max number of writes made to it, in other words, each write made to the SSD is one step closer to its death until it reaches its peak write number, and the thing just dies.

I don't know if I mentioned this earlier in the thread.


With my split (and I didn't run into maflynn's problem, I have >60gb free on my SSD portion), I now very rarely write to my SSD. As I just remembered my point, I have just formulated a way to reorganize my files and folders so that I'm going to be writing to it even less than I am now. I might reorganize things so that I am writing to the SSD the least amount possible. As it is now I am writing to it very little.

Oh btw, for anyone who is skeptical of this idea, the secret to stop worrying about organizing your files is very simple. Use aliases. You know, right click, make alias.

You just put the alias linking to the folder on your HDD on your SSD... and in terms or organization nothing has changed. It is very simple.

For example with the fusion, my volume had a variety of folders as it always had that contain data.

Now my volume has aliases of those folders (and the folders are on the HDD).

In terms of user experience, nothing has changed, but the speed is all SSD.

I'm telling you it's so much better if you organize it all correctly.

 

[steve62388]

Another hidden disadvantage to Fusion drive is that as the above post states, everything is written to the SSD first.

As I understand it an SSD's life span is determined by the max number of writes made to it, in other words, each write made to the SSD is one step closer to its death until it reaches its peak write number, and the thing just dies.

You don't need to worry about this. The endurance of current SSD's is more than enough for desktop use.

http://techreport.com/review/27909/the-ssd-endurance-experiment-theyre-all-dead

http://ssdendurancetest.com

 

[varian55zx]

OK, I am not going to worry about the maximum number of writes to an SSD which in practice is completely irrelevant to 99% of people

It's not irrelevant to me. lol

 

[tentales]

Another hidden disadvantage to Fusion drive is that as the above post states, everything is written to the SSD first.

As I understand it an SSD's life span is determined by the max number of writes made to it, in other words, each write made to the SSD is one step closer to its death until it reaches its peak write number, and the thing just dies.

....

Now my volume has aliases of those folders (and the folders are on the HDD).

In terms of user experience, nothing has changed, but the speed is all SSD.

I'm telling you it's so much better if you organize it all correctly.

Sorry for the lengthy response below, but as a storage consultant for many years, common misconceptions like yours need to be corrected.

I'm happy for you that you're happy with your configuration. Works for you!
Your thinking however is flawed on several fronts and you creating FUD isn't helping the casual user reading your thread.

1) SSDs have limited lifespan (similar to HDDs in case you've forgotten), but it's irrelevant to the average desktop/laptop user, since your device will most likely end up in a recycling heap first before NAND and especially newer 3D NAND expires.
Enterprise users use SLC which has 10x the lifespan of MLC, but 3D NAND has now doubled the theoretical lifespan of planar MLC of around 20K P/E cycles, but I don't want to get too technical here, you can google all this yourself.

2) Creating and keeping track of aliases or symlinks in UN*x speak, is again not for the average user, especially since things could break on major OS upgrades or by user error. Not to mention issues with garbage collection, capacity measurement and backup/restore complications.

3) The whole purpose of deploying an SSD is to speed up frequent r/w. If you now symlink everything of worthwhile volume away from the SSD to the HDD, you're defeating the purpose of having this speedy and costly storage device in the first place. In that case, buy a much cheaper HDD with built-in SSD cache.

4) Control Freak vs Computer Control. You may think you're in better control of where to move data blocks to, but trust me, computer algorithms and CPU speed will do a much better job of "storage tiering", ie. placing frequently accessed data on the faster storage and less-frequent on slower storage than you ever could. Not counting the time and effort you'd need to spend shuffling things around or paying the performance penalty when you don't.

5) User experience:
OS X aka macOS typically executes many background r/w cycles hidden from you and will still "wear out" the typical MLC NAND in your Macbook/iMac. You think your Photoshop editing or Word/Pages doc work is impacting it ? The Fusion drive algorithm is the best consumer grade algorithm available and is heavily based on enterprise storage algorithms. Those have been tested for sometime in much higher write/erase environments than you could ever generate as a single-user. Sorry, but you're just not thinking this through.

Finally to allay others' fears about SSDs lifespans.
Consider this, SSD manufacturers are providing between 3-10 years warranties depending on the type of NAND used. Obviously enterprise level SLC NAND is at the 10 year end of the spectrum.
This "insurance" is typically half the life of what they think it will be. So even the cheapest Amazon SSD you can fetch for under $100 will normally last 6+ years with average workloads. MTBF can vary, but like with any electronics, DOA or premature deaths can still occur, but that's why regardless of SSD or HDD, you should always have a 2 backups, one onsite and one offsite (at intervals).
[doublepost=1469749946][/doublepost]

It's not irrelevant to me. lol

Which makes you part of the 1%. No one's criticizing YOUR CHOICE, but stop telling everyone else to agree to your choice.
[doublepost=1469750731][/doublepost]

Well, my experiment with a split up Fusion drive is over. I found not only the work effort not to be worth it, but the overall management was increased to a point that I felt the downsides outweigh the benefits.

I know everyone's situation is different and my setup and needs is different, so while this may not work for me, it may for others.
My issues is how much space I have for my home folder. I touched upon how much my Library folder consumes, but I don't think I mentioned the other folders. Here's the latest screen grab of my space usage:
View attachment 642222

I'd basically need to either create all sorts of symlnks, modify iTunes and/or move my home folder to the spinning hard drive (and lose some of the benefits of the SSD's performance). My needs are such that I have more data then what could fit on the SSD. Admittedly the contents of the Pictures folder could be moved, but that means a lot of work to reconfigure Lightroom to point to the correct location. Its easy enough to repoint iTunes to another drive, but in my experience that resets itself back to the home user folder.

The point I'm trying to bring up, is the simplicity and elegance of the Fusion drive cannot be overstated. I'm now able to work seamlessly without managing where my data ought to go.

I'm not against splitting up the Fusion drive, I think there are some advantages but at least in my latest go around, I felt those advantages didn't over come the disadvantages. I may circle back on this in the future, but for now, I'm content with letting Fusion handle the data moves.


I've been told that number is theoretically high, that it shouldn't be a concern. I have a 2012 rMBP that still seems to be going strong, even though its being used almost daily

Indeed! You've laid out the case well from the user perspective.
I would go a step further and say there is NO advantage to splitting internal SSDs from HDDs. However, individual perception of performance is a powerful thing

If your use case requires higher performance than what you think a Fusion drive can provide, then you need one or multiple large SSDs standalone or RAIDed together.

 

[varian55zx]

Maybe you already know by now that I don't actually care. If I prefer something some way I may end up voicing it. There isn't much more I can say.

 

[steve62388]

Maybe you already know by now that I don't actually care. If I prefer something some way I may end up voicing it. There isn't much more I can say.

@tentales is right though. Of course enjoy your system any way you want, but it kinda sucks spreading incorrect information because people that don't know better may pay attention.

 

[varian55zx]

@tentales is right though. Of course enjoy your system any way you want, but it kinda sucks spreading incorrect information because people that don't know better may pay attention.

But I'm not incorrect. I'm the only one that is correct.

Others have already vocalized their agreement with me... if your senses are just dulled, it's not my fault. I don't care at all

It's just like the people who can't see the benefit in Retina display. To me it was a massive improvement and always has been.

For some people, the small details are everything, and for other people, they just can't perceive them! That is not my fault

 

[IngerMan]

I will say I tried it and I went back to the Fusion tonight with the help of Mike Flynn. Just some things that needed too much manual intervention. Like Drop Box, iMovie, Mobile backups. The things I moved out of the home folder. Even after creating links or alias it did not like it. My read speeds where up, my write was about the same. But my GEEK bench scores where down. I think the software installed is meant to be fused and if you unlink them maybe it creates too much confusion. IDK, it was a good experience but I won't do it again. And I would not recommend it because the results are inconclusive but the time involved is many hours and great chances of blanking your system from wrong terminal commands to the terms it needs to go back to applecare because you have no other option.

 

[steve62388]

But I'm not incorrect. I'm the only one that is correct.

LOL. That's pretty funny. If you're 'the only one that is correct', what do you think that might be telling you?

The question is can you ever manage a SSD / HDD split better than the Fusion drive algorithm? The answer has to be no because OS X will always move your most frequently used files to the SSD portion, whether that be the operating system, apps or documents.

For example. You have decided to install OS X on your SSD. You don't use every file in the operating system regularly, so you have no idea which files to move. But the Fusion algorithm does. (I'm using the word 'file' for simplicity, but Fusion actually works on a block level).

 

[varian55zx]

LOL. That's pretty funny. If you're 'the only one that is correct', what do you think that might be telling you?

what do I care? You're admitting to me now that I'm right and then you're trying to tell me to do something about it

That is ridiculous.

I will say I tried it and I went back to the Fusion tonight with the help of Mike Flynn. Just some things that needed too much manual intervention. Like Drop Box, iMovie, Mobile backups. The things I moved out of the home folder. Even after creating links or alias it did not like it. My read speeds where up, my write was about the same. But my GEEK bench scores where down. I think the software installed is meant to be fused and if you unlink them maybe it creates too much confusion. IDK, it was a good experience but I won't do it again. And I would not recommend it because the results are inconclusive but the time involved is many hours and great chances of blanking your system from wrong terminal commands to the terms it needs to go back to applecare because you have no other option.

Maybe you're a genius like me and you solved the fusion drive, or maybe you didn't. If you haven't, I wholly encourage you to do so. And if you have, then that is good for you, you know what it's like.

hah I am only kidding but I do have absolutely no intention to refuse it, as my user experience is superior with it unfused.

 

[steve62388]

what do I care? You're admitting to me now that I'm right and then you're trying to tell me to do something about it

That is ridiculous.

I see reading comprehension is not a strong suit.

If you think you're the only one that is correct and everybody else thinks something different, it means you're probably wrong.

 

[varian55zx]

Steve, what you're saying is so important to me.

 

[JustMartin]

It does depend on your goals. The way I see it, varian55zx's goals are:

To minimise the the load time of applications and operating systems components (no matter how often they're used)
To maximise the performance of the SSD by keeping a large part of it free
To extend the longevity of the SSD by minimising write activity

The maintenance workload for the above goals is not very high because effectively you're freezing the contents of the SSD for long periods. It's only O/S or apps upgrades that will force a change. And if you ignore benchmarks and only work on the 'feel' of the system or count bounces before an app loads, then it will work for you.

But, if your goals are more real world and you want to make the most of the hardware behind the screen, then I suggest Fusion is a better way to go. I want Word to open quickly and then I want it to load my latest magnum opus quickly and save it without delay when I ask. I don't care which bits of MacOs I use, I do want the frequently used bits to execute more quickly because that's where the time savings make most impact (the things I use every 6 months can take longer, it's not going to make any difference). The similar case can be made for whatever type of work you do, especially when dealing with largish files like pictures or sound.

If your application stays running, but the files you use keep being loaded and unloaded, then for me the biggest bang for the buck is in decreasing the load times of the content, not the application.

 

[maflynn]

2) Creating and keeping track of aliases or symlinks in UN*x speak, is again not for the average user, especially since things could break on major OS upgrades or by user error. Not to mention issues with garbage collection, capacity measurement and backup/restore complications.

I don't know if I vocalized that issue, where if I used a number of symlinks, I was worried what an update/upgrade would do.

Back in the day, I moved my home folder (back before Apple gave you an easy process) and I had issues with some apps and updates. You're 100% correct

But I'm not incorrect. I'm the only one that is correct.

Ok then.
I suppose there's no reason having a civil discussion over the pros and cons with you. Btw, I said this before, I'm glad you're happy with your arrangement, but based on my limited research and knowledge, what @tentales wrote. There theoretical EOL of a SSD is well beyond that of the computer, the computer manages the data more seamlessly. I found that I'd rather manage my work, then manage where my data goes, and on the backup front, the Fusion drive definitely makes life easier. One size doesn't fit all, and all in all, you're happy with your setup, I'm happy with mine

Peace.

 

[IngerMan]

Varian can you post your Geekbench score with your defused hard drives? I was over 150 points lower when I defused. I noticed much more kernel task activity in that state, like it kept trying to fix something. Below is my score after switching back to Fusion

 

[tentales]

I don't know if I vocalized that issue, where if I used a number of symlinks, I was worried what an update/upgrade would do.
...

Yes I saw that and I included it in my summary of disadvantages. Operating system file structures have moved many times between each flavour of Un*x and version, despite POSIX compliancy. As a side note, Darwin, on which OS X is based, has mutated its core structure many times. It's an evolutionary process, which interested parties can read up on here: https://en.wikipedia.org/wiki/Darwin_(operating_system)

So if people come on here debating about "improving" performance by messing with the underlying structure of the OS, they better be system architects or IEEE members. Having worked in 3rd level support, I grew tired of being at the receiving end of too much half-knowledge confusing the heck out of end users and having to spend my time debugging avoidable problems.

To say it again, if anyone's needs are such that they'd rather split a Fusion drive, then just cough up the dough for a 1TB SSD only or if you need more there are RAIDed Thunderbolt SSD solutions out there. The Fusion drive IS the best compromise between performance & cost.

Full disclosure, my own setup uses a 2TB Seagate drive fused to an OEM 256GB SSD. Hence, I have a 2.2TB drive that feels like an SSD 99% of the time. I chose to buy a MacMini (refurb) with the 256GB SSD, to double the size of the fast portion of my Fusion drive and added an internal 2TB drive. Also, if you order a 1TB Fusion drive from Apple these days, the SSD portion is a tiny 24GB, which you probably already knew.

EDIT:
I could only think of one use case for splitting Fusion drive. If you spend considerable time running bootcamp and require SSD speeds in your Windows OS. I prefer the VM route to run both OS X & guest OS on Fusion. However, again, one larger SSD only config. would be better than splitting.

 

[hfg]

EDIT:
I could only think of one use case for splitting Fusion drive. If you spend considerable time running bootcamp and require SSD speeds in your Windows OS. I prefer the VM route to run both OS X & guest OS on Fusion. However, again, one larger SSD only config. would be better than splitting.

You can have Windows on your SSD and keep the Fusion drive. My 2012 Mac Mini (2 drive server model) has a hard disk and a 512GB SSD divided into 2 partitions. One 256GB SSD partition holds a bootable Windows 10 bootcamp installation. The other 256GB SSD partition is joined with the hard disk as a Fusion drive. Simply use the disk#s# value when creating the Fusion drive. I also access the bootcamp Windows as a virtual machine with VMware Fusion from within OS X. Works great!

 

[tentales]

You can have Windows on your SSD and keep the Fusion drive. My 2012 Mac Mini (2 drive server model) has a hard disk and a 512GB SSD divided into 2 partitions. One 256GB SSD partition holds a bootable Windows 10 bootcamp installation. The other 256GB SSD partition is joined with the hard disk as a Fusion drive. Simply use the disk#s# value when creating the Fusion drive. I also access the bootcamp Windows as a virtual machine with VMware Fusion from within OS X. Works great!

Yes that also works.
Just to know, the older 2012 model had room for 2 internal SATA drives and allows you to swap 3rd party SSDs but at slower speeds than PCIe.
OTOH the 2014 MacMini has much faster PCIe SSD but alas it's OEM and more costly, especially if you select the 512GB or higher option. Or you could switch the SATA drive for a 3rd party 1TB SSD SATA drive, but then no Fusion necessary or doable.

 

[maflynn]

I wanted to update my situation since I mentioned this in another thread and some of my discussions may cause some confusion.

I found myself de-fusing my drive once again, this time for a specific need that I found no other alternative.
Background: I'm using Windows more and more and I needed to "upgrade" my windows situation from using the spinning drive to something faster. Obviously the easiest solution would be just use an external SSD, which I tried but I quickly found out Windows does not (by default) install onto a USB drive. I found this thread: Bootcamp Windows 10 from External Drive? Post #87 has steps to make a Windows to Go installation which worked, but when Anniversary edition came out, it would not upgrade (again because of Windows not wanting to be on a usb drive).

So that left me with rebuilding my external drive and reinstalling windows by those steps or install windows on a soon to be defused drive and that would alleviate me from any future upgrade hassles.

First thing I did was buy a Samsung T3 500GB SSD (My old external SSD was no larger then the internal 128GB)
I cloned my OS X drive, restored that to the T3 and booted that up.
I then defused the drive, ran those steps on Post #87 because bootcamp on my external drive was not cooperating and this seemed the easiest approach to get windows installed.
I also split up my spinning hard drive into two partitions 1 TB each. One for Windows, and one for OS X.

At the end day my OS X volume is large enough on the external SSD to hold everything but my images to avoid any and all symlinks and my windows volume is on the internal drive and is fine on the 128GB drive without any space issues. Unlike OS X, I found it easier to move much of my data onto the spinning drive.

To summarize, OS X is completely on a fast SSD (by way of USB 3.0) and my windows environment is on a fast SSD.