Well worth considering is a Solid State Hybrid Drive (SSHD)"Would a 512GB SSD + external USB drive not perform similar to the 128GB+2TB fusion drive?
Assuming almost all data would be kept externally, surely the fusion route would be better?"
NO to both questions.
Fusion is never "better".
Rather, it is (was?) a "stopgap solution" to eking more speed out of the lower-priced iMacs without putting an SSD into them.
The "fastest way" would be an iMac with an SSD inside, and then attach fast USB3 storage OUTSIDE. The external drive can be an SSD, or even an HDD. But DON'T "tie it into" the internal SSD using fusion.
Fusion can only slow an existing SSD down.
This is a 100% certainty.
1. The SSD portion is used to save the RAM state during standby mode so installing more RAM than SSD may nullify the fusion benefits. Apple recommends only using a 1TB fusion if you have 8-16GB RAM.Are there any downsides to the 1TB FD that are installed in the 3.4, 3.5 and 3.8GHz iMacs?
Macs with pure SSDs are custom build-to-order configurations usually ordered directly from Apple.I dont think there i an option for a pure SSD!
That and speed. The 21.5" has HDDs that are physically smaller and slower. The 21.5" iMac Fusion drives are SSD + 2.5" 5400rpm HDD while The 27" iMac Fusion drives are SSD + 3.5" 7200rpm HDD which are almost twice as fast.What does the 21-5" screen has to do with the drive, is it a matter of space?
What happens on the 27" i mac?
Put your OS and apps on and external SSD drive and boot from that. Use the internalI dont think there i an option for a pure SSD!
[doublepost=1526447437][/doublepost]What does the 21-5" screen has to do with the drive, is it a matter of space?
What happens on the 27" i mac?
What i was asking is how much faster is to boot from an extSSD drive, compared to the a FD thats built in the iMac ;-)You are a doubting Thomas.
An SSD, internal or external, is up to 6X faster than the slow laptop style 5400rpm slow as molasses hard drive. An external will run at about 85-90% of the speed of the same SSD internally. Watch this for comparison:-
If there is a difference, I suspect the FD would boot faster since its booting from an internal SSD. The issue with Fusion really is the small SSD size on most of the options compared to the larger SSD only option. My personal use makes my Fusion 2TB setup fine for me since all of my data fits easily on just the 120G SSD. I see fast boot time and fast use times. If I were using my computer for a different task maybe it would make a much bigger difference.What i was asking is how much faster is to boot from an extSSD drive, compared to the a FD thats built in the iMac ;-)
But i assume that the FD is faster than a HD right?
Don't listen to the haters -- go to the Apple Store and find a Mac with a Fusion Drive and try it out yourself. They're much faster than a spinning HDD. The logic of the Fusion Drive is that it moves whatever files you use the most onto the SSD portion and runs them from there. So if you have a 2TB Fusion Drive, you have a 128 GB SSD with your most-used files on it. Your older and less-used stuff is right there too, stored on the HDD.This thread has got me scratching my head now. I am looking at buying a new iMac to replace my old MBP and was going to get the 2TB FD version. It's and extra £1260 UK for a 2TB SSD. Are the FD's really that bad??