HELP - iMac 2019 (fusion) slower than 2015 (SSD) & how to share external NVME drive

[netmac]

The 2 iMac are actually for my wife. I am a Window person. I am just her IT person, but I don't Mac very well. I use "I" below for simplicity. 😁

I have a 27" iMac 2015 with 8GB RAM + an internal SSD. BlackMagic rates it at 600MB/s.

I also have a 21.5" iMac 2019 with 8GB RAM + 1TB fusion drive. BlackMagic rates it at less than 150MB/s after a few seconds. Everything on the iMac 2019 is SLOW. Bootup time can take 2+ minutes. The purchase of this configuration was a bad decision. I didn't know that even a fusion drive is slow. This should never be produced.

Recently, I built a NVME external thunderbolt 3 drive to use as the startup drive for iMac 2019. BlackMagic rates it at 2300MB/s. Everything is much faster than before on the iMac 2019, but it is still not as responsive as iMac 2015. I really don't know why. 😭 Any idea??? 😅

Since iMac 2015 is more responsive, I want to use the external drive as the startup drive for iMac 2015 as well, because I have a lot of files in the drive. It is nice to be able to keep the files in one drive and use it on both iMac. But iMac 2015 has only thunderbolt 2. I bought a thunderbolt 3 to thunderbolt 2 adapter and a thunderbolt 2 cable. Then I found out that the external thunderbolt drive needs to be self-powered.😅 There are not many options for a self-powered NVME thunderbolt enclosure. I am in EU. The one that I find is SABRENT Thunderbolt 3 to Dual NVMe M.2 SSD Tool-Free Enclosure, which is twice more expensive than if bought in the US!!!

SABRENT Thunderbolt Dual NVMe Enclosure, 2 Bay m2 SSD Docking Station, 40 Gbps, Tool-free (EC-T3DN)

The tool-free dual enclosure Sabrent Thunderbolt 3 To NVMe M.2 SSD is the perfect solution for your external storage needs! FEATURES: COMFORT: Turn two NVMe SSDs into two independent, fast, reliable and portable drives. Plug and play, no drivers required. Design: Solid aluminium construction for ...

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So now I really need help to find out what I can do to improve my current slow iMac 2019 situation.

1) Why is iMac 2019 with a thunderbolt 3 drive as the startup disk still slower than iMac 2015 with a SDD?

2) What can I do to share an external NVME drive between the 2 iMac affordably? Should I get a different enclosure or a different type of drive to share between the 2 iMac?

Your expert suggestion is much, much appreciated!!!

 

[Fishrrman]

I have a solution for the 2019 iMac.

Get an external SSD that is USB3.1 gen2.

Clone the contents of your fusion drive onto the SSD, and set the SSD to be the new boot drive.

You'll get read speeds of around 850MBps or better, a BIG "bump" upwards.

Do this, and I predict you (and your wife) will be VERY pleased at the performance improvements.

For a drive, I'd suggest the Samsung "t7 Shield".
(not the regular t7, get the "Shield" version, which folks report as having better throughput).

I bought one myself a couple of weeks back, I don't use it as a boot drive, but it gave me read speeds of about 950MBps using BlackMagic.

When you get the drive, do this:
1. Connect it to the Mac and open disk utility.
2. Check to see if disk utility has a "view" menu. If it DOES, go to it and choose "show all devices" (important that you do this).
3. Now, we want to ERASE the SSD completely.
4a. If you're using Mojave or later, erase to "APFS, GUID partition format"
4b. If you're using High Sierra or earlier, erase to "Mac OS extended with journaling enabled, GUID partition format".
5. When the erase is done, quit disk utility and go to next step.

I recommend that you now "clone" the contents of the fusion drive to the SSD using either CarbonCopyCloner or SuperDuper.

Both are FREE to download and use for 30 days. Doing things "my way" costs you nothing.

I suggest SuperDuper as it's a bit easier for a first-time user. VERY easy.

So use SD to clone the fusion drive to the SSD, it will take a little while.

When done, go to the Startup Disk preference pane and set the SSD to be "the new boot drive".

Then reboot. If things went right, the Mac should boot faster and you should see the login screen (same as before, because it's a clone).

However... things should go considerably FASTER now.

If you choose to go this route, please come back to this thread and let us know of your experiences.

Last thought:
For a 2019 iMac, DON'T BOTHER with thunderbolt.
USB3.1 gen2 is "the right way to go".

Good luck!

 

[rpmurray]

I have a solution for the 2019 iMac.

Get an external SSD that is USB3.1 gen2.

Clone the contents of your fusion drive onto the SSD, and set the SSD to be the new boot drive.

You'll get read speeds of around 850MBps or better, a BIG "bump" upwards.

Do this, and I predict you (and your wife) will be VERY pleased at the performance improvements.

I think you may have missed the following portion of the OP's post:

Recently, I built a NVME external thunderbolt 3 drive to use as the startup drive for iMac 2019. BlackMagic rates it at 2300MB/s. Everything is much faster than before on the iMac 2019, but it is still not as responsive as iMac 2015. I really don't know why. 😭 Any idea??? 😅

So they already have a Thunderbolt external that blows the doors off any USB external.

I think the next step would be to find out what the OP means by the TB being much better but still not as responsive. How are they measuring responsiveness? Or, to be more precise, what are they comparing that makes them believe that?

 

[netmac]

I have a solution for the 2019 iMac.

Last thought:
For a 2019 iMac, DON'T BOTHER with thunderbolt.
USB3.1 gen2 is "the right way to go".

Thank for the reply.

Currently, I am using the thunderbolt 3 NVMe external drive as the boot drive for the iMac 2019. BlackMagic rates it over 2300MB/s for both read and write. I did exactly what you suggested. I erased and formatted the drive with APFS and cloned it with CarbonCopyCloner. The speed does improve a lot. But it is still slower than iMac 2015! It was not usable, but now it is sluggish but bearable.

 

[Fishrrman]

OP:

Sorry, missed the part about your already having the tbolt drive.

With the thunderbolt drive you have, reporting speeds as posted above, your problems, whatever they may be, ARE NOT the drive or "drive speeds".

I would try creating another, temporary user account (users & groups preference pane).
Give it administrative privileges.
Then log OUT of your "regular" account, and log into the new, experimental account.
Do things seem to go faster?

If so, it could be something in your original account that is slowing things down.
You'll have to do some detective work to discover what it is.

 

[USB3foriMac]

Since you have a spinning drive internally, the iMac system will always be slower, as the system has to wait for the drive to spin up at boot and after sleep.
To get to the same speed as the 2015, you have to remove the drive entirely.

 

[netmac]

So it turns out that it is the antivirus AVAST that slows down the 2019 iMac. The 2015 iMac has AVG installed and it was not a problem. After I replace AVAST with AVG, the problem goes away. It is normal now, about the same as 2015 Mac now. 😀

 

[Fishrrman]

My opinion only, but the "antivirus software" isn't worth running.
There has been ZERO Mac viri discovered "in the wild" since OS X was introduced back around 2002 or so. Not a single one.

I run no "in the background" virus software at all, never have.
I DO run MalwareBytes now and then, and once it actually found some adware/crapware.

 

[netmac]

My opinion only, but the "antivirus software" isn't worth running.
There has been ZERO Mac viri discovered "in the wild" since OS X was introduced back around 2002 or so. Not a single one.

I run no "in the background" virus software at all, never have.
I DO run MalwareBytes now and then, and once it actually found some adware/crapware.

That is good to know. I will look into it. Thanks!