Fusion drive between NVMe and SATA SSD?

[smirk]

My late-2015 27" iMac has been feeling slow lately when there's a lot of disk access going on (like when running VMWare). It's pretty clear the bottleneck is the existing 2.2TB fusion drive. I was thinking of replacing the stock drive components with a 2TB NVMe, but then was wondering if some money could be saved by fusing something like a 2TB SATA SSD with a 250GB 970 EVO NVMe.

Is there any benefit to creating a fusion drive with two SSDs like that, or is that just asking for trouble?

The reason I like fusion is because I prefer working with one logical volume.

What do you guys think? Thanks!

 

[Lankyman]

We have two iMac's, one has SSD the other the 2TB fusion drive. I don't get any discernible advantage from the SSD iMac and have no regrets whatsoever in choosing the Fusion drive for our newer iMac. For your average user I don't think you can go wrong with the fusion drive.

I would do some further research to ascertain what is slowing down your iMac.

 

[Fishrrman]

"Is there any benefit to creating a fusion drive with two SSDs"

No.
No benefit.
Run them as "standalone", separate drives.

I'll bet they run better and longer that way.

 

[niteflyr]

If VMWare is causing a lot of disk swapping, perhaps more RAM would help. How much Ram is installed?

 

[smirk]

If VMWare is causing a lot of disk swapping, perhaps more RAM would help. How much Ram is installed?

I'm not sure that it is swapping VM, I think that it's just using the drive in the guest OS to the detriment of the host. But I'm not really sure.

It is doing it right now, where the guest is virtually unusable and the host is fairly slow. Activity Monitor shows 8 GB physical memory, 5.75 GB Memory Used, 1.90 GB Cached Files, and 67 MB Swap Used.

 

[niteflyr]

8 GB of RAM is minimal for running VM's especially if more than one. If you are going to upgrade the SSD I would add more RAM also or try adding some RAM first and see if that makes things more bearable.

 

[Zandros]

"Is there any benefit to creating a fusion drive with two SSDs"

No.
No benefit.
Run them as "standalone", separate drives.

I'll bet they run better and longer that way.

It's easier to manage files on a single volume. I'm sure a single volume with JBOD will be worse than using them in a Fusion drive.

 

[smirk]

It's easier to manage files on a single volume. I'm sure a single volume with JBOD will be worse than using them in a Fusion drive.

@Zandros, I'm not sure I follow you. I agree that it's easier to manage files on a single volume, but isn't a fusion drive basically a JBOD?

 

[Zandros]

@Zandros, I'm not sure I follow you. I agree that it's easier to manage files on a single volume, but isn't a fusion drive basically a JBOD?

Fusion drive is supposed to manage your data so that more frequently accessed files are on the faster portion of the setup. I don't think JBOD does anything like that.

 

[imacmann]

"Is there any benefit to creating a fusion drive with two SSDs"

No.
No benefit.
Run them as "standalone", separate drives.

I'll bet they run better and longer that way.

I'm not even sure it's possible to use two SSD's as a fusion drive is it? I tried and it said it had to be a SSD and mechanical drive.

 

[Jonesies]

It's easier to manage files on a single volume. I'm sure a single volume with JBOD will be worse than using them in a Fusion drive.

Thank you for this! So much wrong info out there and I’m hoping you can confirm this. I’ve spent the last month researching my options for my 5k late 2015 iMac with a fusion drive. I’ve upgraded ram to 48gb and needed more for video editing. So I went all in with an external thunderbolt 3 nvme enclosure with the Apple adapter and then hit a wall. Just wasn’t as reliable as I wanted and kind of bottle necked around 450 r/w speeds. So, then I bailed on that as there’s very little TB2 support these days. I’m now going to open this thing, leave the 1tb spinning drive, and go straight to the 24gb Apple flash. Upgrading that to a 1tb m.2 nvme with the $16 converter for proper fit. I’ll disable the fusion and crush performance with massive blade speeds. Then, I’ll have the spinner as internal backup for larger files and my 8tb seagate external for larger backups and clones. Now, if this sounds wrong to anyone, speak up please. But from my understanding, this is close to the best performance possible. Of course, upgrading the i5 to the i7 6700k 4.0ghz would probably be the only other value move to make. Anyway, thanks for all the good info in this thread!

 

[smirk]

What you propose is along the lines of what I wanted to do, but I haven't been able to tell from other posts on this forum how well it will work on this model iMac. I want to speed up my computer, but without sacrificing stability or the ability to sleep (and wake) correctly.

The only thing I might change about your plan is to replace the five year old spinner with something newer. It would be a shame to go through all that effort and then have your backup drive die, and then have to open it up again.

Good luck with the upgrade. Please let us know how you make out.

 

[SKYNET-1]

with a fusion drive u will loss around 1500MB/s(=700-800MB/s) write from the NVMe, only the read speed will be normal... so dont waste a thought about the fusion sh*t(seperate drives always better)

 

[Hassanmahroof]

Hi, I found this method and it seems to have worked so far for me. Click Here. Currently installing MacOS on the machine. Will update with whether it was successful.