MY [incomplete] home folder is consuming 49GB. 46 of that 49 is in my ~/Library and specifically most of that space is MobileSync.
So basically, I have 95GB allocated, and 25GB free
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Case For Unfusing the Fusion Drive
- Thread starter varian55zx
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So basically, I have 95GB allocated, and 25GB free
You may not need a lot of that to be on the SSD. The only things I leave on the SSD boot are are OS files and applications (including games). Everything opens quickly. Documents, photos, music, video - these generally don't need to have the speed your solid state drive provides. The applications need it.
Yep, and I haven't properly measured things but I sense that modern versions of the OS are unexpectedly slow over USB.
Agreed, and if I am to keep these two drives seperate, I'll have to move my home folder.
As it stands, the 46GB out of my 49GB of home folder data is not documents, images or music, but rather in ~/Library. While I can temporarily improve that by cleaning the cache folder, that will eventually start filing up
That's a lot in Application Support. The iMac I use here at work has 32 Adobe applications in addition to a handful of others that aren't stock. My System Library is only 13GB. My Home Library is 15GB. Is that MobileSync stuff being stored in Application support? That looks really high. There might be data that can be deleted or saved to another location.
No question, most of that is the backups found in mobilesync. I not only back up my iPhone, but also my kids on my machine. I think that adds up to a lot space.
Can you redirect where that back up is being stored? If not, maybe move them off manually?
I doubt it, but I can google it.
I suspect, it can be resolved if I move my home folder to the spinning drive.
That's strange. Android let's me browse to any location on my phone, SD card, or computer system to back up and retrieve. I don't know anything about iOS. It seems silly that you wouldn't be able to do that in the year 2016. This is Apple, though.
Do you get the feeling that you are doing manually that which Fusion does automatically and with far better granularity?
Interesting experiment however .... and I am sure many of us will be anxious for your conclusions.
At this point, I'm not sure. This was done more of a proof in concept and see how I feel. I think the overall difference is keeping the OS and apps on the SSD, so unlike the Fusion logic that will move data blocks on and off the SSD, I'll be keeping what's on the SSD, fairly static - provided I keep this arraignment
When I get home from work, today, I'll move the home folder and and give it a bit of time to see if this setup works for me. I'm not entirely sold that it will. I think letting Fusion do the work and only have one logical volume makes a lot of sense.
Move the MobileSync (iOS backups) folder to your hard drive, and symlink it back to where it was. There's no reason to have iOS backups on your SSD.
That alone should free up enough space for you to be comfortable.
I totally get your pain, though, and I'm actually thinking of buying an external Thunderbolt SSD for my machine so I can have more data on solid state. This is far better use of my $$ than trying to upgrade the internal SSD, since a Thunderbolt SSD can be moved to a new computer when I upgrade.
I suspect having your home folder on the SSD will be beneficial due to frequent access to the data libraries stored there.
The problem I have with splitting the Fusion drive is the granularity to which I am able to manage manually. I would simply decide to put, say, the Applications folder on one drive or the other, even though I probably only regularly use a select set of the Apps contained there, and the rest might as well be on a slow disk. Same with other OS and library files, I probably only actually use a select few in day-to-day usage, and the rest just sit there unused for the most part. Yes, I could try to figure out how to split them up ... but it is too much work to do manually ... or often, so I would simply place them all one place or another.
I have moved to larger SSDs to avoid the problem, especially in the case of my iMacs since they are so hard to internally upgrade. One suggestion ... if you don't mind a bus powered external SSD Velcro'd on your iMac stand, would be to put your OS, apps, etc. on the internal boot SSD, and then have your home directly on the external SSD (which would still be pretty fast), and use the hard disk for backup or for static libraries (music, video, etc). With the lower SSD prices available now, you could put a 1TB SSD externally, have your OS stuff internally, and the 2TB hard disk would make a nice Time Machine backup for it all ... plus you would still have the look and feel of an all-in-one iMac.
@maflynn a few quick thoughts (it's getting late here):
- don't think of boot times (assume that you'll rarely need to reboot; a warm or hot cache is a good thing)
- don't overfocus on app launch times (assume that some or most of those times will benefit from a suitably warm unified buffer cache)
- don't plan to measure things, instead be prepared to take a holistic view (how the Mac 'feels')
- aim to use the fast storage for databases; for metadata.
And, how about giving us the option in System Preferences to fuse or unfuse drives?
Yeah ... I too have wished for BTO options to select the SSD and Hard Disk separately and then the user could decide how they wanted to use them and whether to make Fusion drives or not (or partially ... I like to have my Windows boot on a SSD partition, with the rest of the SSD and hard disk in a Fusion volume. It would then be necessary to have the Fusion commands in DiskUtility or somewhere to be easy ... but the Terminal commands are easy enough for now.
Looking ahead …
System Preferences
Given what's known publicly about APFS, I doubt that anything related to Core Storage will be added to System Preferences.
In cases where (a) the customer wants the benefits of APFS and (b) the amount used on the startup volume (an LV) exceeds what can be stored on the larger of the two disks: I expect that there will be encouragement to optimise storage (enough to allow partitions on both disks to leave Core Storage world, although I don't expect that goal to be explicit in any preference pane).
System Information
In the storage part of the application, there may appear a recommendation (or suggestion) to defuse things and use Apple File System instead.
System Preferences
Given what's known publicly about APFS, I doubt that anything related to Core Storage will be added to System Preferences.
In cases where (a) the customer wants the benefits of APFS and (b) the amount used on the startup volume (an LV) exceeds what can be stored on the larger of the two disks: I expect that there will be encouragement to optimise storage (enough to allow partitions on both disks to leave Core Storage world, although I don't expect that goal to be explicit in any preference pane).
System Information
In the storage part of the application, there may appear a recommendation (or suggestion) to defuse things and use Apple File System instead.
Yeah, good point, I was wondering about that. I messed up moving my home folder last night. I was trying to do two things at once that didn't work. I'm now restoring my CCC backup to get the system back to the way it was.
Good suggestion, I'll go and do that.
After defusing your drives and creating symlink's, what will happen when you upgrade to the next operating system, say OS Sierra? Will it recreate subfolders in your home folders on the SSD? Anyone know someone that did this then upgraded to the next operating system?
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The time spent pondering the optimal storage setup, moving data, managing files as usage patterns and OS versions change in addition to capacity management, and the backup/restore cycle to try Fusion vs unFusion is IMHO at least 100x higher than the time saved, perceived or real, for splitting SSD & HD partitions apart.
But, to each their own. Some folks like to manage their computer, I'd like my main computer to help me manage actual work.
For tinkering, I'd buy a Windows box and run Linux on it.
My preferred setup, Mac Mini with factory 256SSD, upgraded with 2TB HD internally to manually create 2.25TB Fusion drive.
Exception, if you frequently run bootcamp, then instead of Fusion to a HD, run 2 x SSDs internally and a larger drive externally.
I agree, the time savings is not there, but then I wasn't going into this to unfuse the drive, but rather I needed to restore my system, and I already had a backup, so since I was already going to do a restore, why not.
Either way, I was going to be spending time restoring my system, so why not try something different and see if this improves my user experience?
I've stated in this thread and elsewhere, that I have some misgivings on the benefits of splitting up the Fusion drive, but as they say, nothing ventured, nothing gained. I'm willing to spend some time to hashing this out and see if there's an improvement.
I agree with you, however Apple has done a good job with Fusion and I was happy with it, but I'm willing to try something different.
By all means, I wasn't trying to be critical of you trying it. I have done so in the past. I've worked years in data storage and optimizing user experience for large corps. The Fusion drive algorithms were not invented at Apple, but is the 1st consumer level storage tiering implementation tmk that's been around for decades in the enterprise storage world. On other Un*x platforms it's generically known as LVM + LVG aka HSM. A decent primer on how this works can be found on SNIA's website: http://www.snia.org/sites/default/e...torman/LarryFreeman_What_Old_Is_New_Again.pdf
My basic point was this, no need to screw with the Fusion drive defaults. It's pretty darn good for 90%+ users. There are specific use cases requiring higher performance, but they don't involve internal spinning drives.
Well I just had to try it. Hind site I should of got the 256 Flash but at the time I had about 180GB of data on my old mac. But after doing some house cleaning yesterday and seen I had many duplicate files from Drop Box, so I cleaned down to 110GB of space.
I figured everything must be on the SSD at that point but I was close to being at the max 120GB. I also thought why not try it now and manage my Music, Photos, Movies on the hard drive going forward. That is only 3 media types to manage, should not be difficult, or time consuming.
My Photos/Music/Movies on the HD and everything else is on the SSD. I symlink the 3 folders and will see how that goes when I start downloading or updating.
It does seem a little more responsive not that it was slow but it does seem a tad faster. Black Majic test troubled me when I had 180GB of data, it would be anywhere from 150 write to 600 mb/s and the read would also be all over but upto 800 mb/s. Al most like excel decel excel etc. After I got it down to 110GB of data it would constantly display 600's write and up to 1400 Reads. But after defusing it is the fastest I seen the test run. Granted this test probably does not mean a whole lot, its the feel. But the machine did feel faster when I got under the 120GB and that made me make the switch.
I am impressed with the read write speeds of the HD. I am getting 180's mb/s for both read/write. It was not that long ago I had a SSD at 250mb/s and thought that was awesome.
I am like some of the other guys that like to tinker and try stuff. It was not necessary but Ill see how she runs down the road for a while before I can say was it worth it. I got 52GB on the SSD and the rest on the HD
I figured everything must be on the SSD at that point but I was close to being at the max 120GB. I also thought why not try it now and manage my Music, Photos, Movies on the hard drive going forward. That is only 3 media types to manage, should not be difficult, or time consuming.
My Photos/Music/Movies on the HD and everything else is on the SSD. I symlink the 3 folders and will see how that goes when I start downloading or updating.
It does seem a little more responsive not that it was slow but it does seem a tad faster. Black Majic test troubled me when I had 180GB of data, it would be anywhere from 150 write to 600 mb/s and the read would also be all over but upto 800 mb/s. Al most like excel decel excel etc. After I got it down to 110GB of data it would constantly display 600's write and up to 1400 Reads. But after defusing it is the fastest I seen the test run. Granted this test probably does not mean a whole lot, its the feel. But the machine did feel faster when I got under the 120GB and that made me make the switch.
I am impressed with the read write speeds of the HD. I am getting 180's mb/s for both read/write. It was not that long ago I had a SSD at 250mb/s and thought that was awesome.
I am like some of the other guys that like to tinker and try stuff. It was not necessary but Ill see how she runs down the road for a while before I can say was it worth it. I got 52GB on the SSD and the rest on the HD
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.
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