Whats my best configuration to boot of external SSD (with the setup I have).

[dcmaccam]

Hi Looking for some more advice. Had my old 2011 27" iMac booting from an external Thunderbolt connected drive. (Lacie Rugged with the permanent attached TB1 cable). This drive has a 500GB Samsung EVO 860 drive installed. Trim was also enable using Trimforce.

Now I got a new 2019 iMac at a really good price. It has a Fusion drive. So I wanted to setup the Thunderbolt drive that I had on the 2011 machine on the 2011 machine. To do this I had to get a Thunderbolt 3 to 2 adapter which came today. I plugged in the adapter into the Mac and the cable into the adapter (I restored an image onto the SSD). I then booted from the drive and enabled trim using trimforce.

Now the Blackmagic disk speed test gives me lower that expected 334Mb/s Write and 384Mb/s Read which is lower than I expected (maybe the adapter is lowering the speed).

As a comparison I also have a 1TB. Lacie Mobile SSD which has a USB C connection I get 480Mb/s write and 520Mb/s read

Now using what I have what would be the best configuration given that you can't enable trim support on a USB connect SSD

Or would I be better to just use the original Fusion drive as the boot drive and use these two drives for backup or storage?

Once again any info/help would be much appreciated.

 

[Fishrrman]

I suggest you use BlackMagic Speed Test to do a read/write test on the fusion drive as it is RIGHT NOW.

Post those results here.

If it was me, I'd use the USB3 external drive to boot and run from (if you don't want to boot from the fusion drive). MUCH better speeds than the thunderbolt drive you have.

For even faster speeds (about 965MBps reads), you could put together an nvme "blade" SSD and a USB3.1 gen2 enclosure (many available at amazon). Very cost effective. One thing to be aware of is that blade nvme drives can run on the hot side during heavy write loads. But probably fine for regular day-to-day use as a boot drive.

 

[dcmaccam]

Did a Black Magic speed test on the Fusion drive. Bit strange,probably because the drive type. Did 5 cycles at 5GB

Write Read
661 1322
146 260
111 128
665 1024
99 110


With regards using the USB drive to boot and run from is it any great concern that you cannot enable trim on that drive. That was the reason I used the Thunderbolt instead.

Will look into the blade option once finances allow.

I will mainly be using the machine for Lightroom and a little bit of editing with Premier Elements.