disk1 - Samsung SSD 870 EVO 2TB 2.00 TB (Solid State - TRIM: No)
Internal SATA 6 Gigabit Serial ATA
The storage change was not well-handled. Your iMac originally shipped with Apple's Fusion (hybrid) drive that used software to link a small NVME solid-state drive (SSD) to a larger SATA 6G 7200rpm mech drive. The tech should have installed a blade SSD in the slot where the Apple 28GB blade is now, if the point of the change was to speed up the computer.
My collection of EtreCheck drive scores shows that a healthly Fusion system in your 2017 5K iMac should do Writes between 600 and 900MB/sec and Reads up to 2000MB/sec. Installing an SATA 6G SSD in place of the Fusion componet and breaking the Fusion connection reduced the max possible speeds to what yours now shows:
Performance:
System Load: 1.23 (1 min ago) 2.25 (5 min ago) 2.99 (15 min ago)
Nominal I/O usage: 0.41 MB/s
File system: 20.79 seconds
Write speed: 489 MB/s ⚠️
Read speed: 519 MB/s ⚠️
Recommendations:
1) Before whacking and hacking, I first recommend running EtreCheck again, this time with any USB-2 (480MB/sec)externals disconnected (your disks 6 and 7 in the report). As crazy as it sounds, I'm seeing reports here recently where disconnecting an older USB-2 external enclosure improved the internal drive scores. Worth the extra data point.
2) Enable TRIMforce on your Samsung SSD. Over time, SATA SSDs are slowing if TRIMforce is not enabled. Yours is not yet there but it will be. It took about 2-3 years to happen on my Mac with an aftermarket SATA SSD upgrade, Enabling TRIM solved that, but the write scores had dropped by 90% before I found the problem. Instructions: How to enable TRIMforce.
👉🏻NOTE: After engaging TRIM on my Mac, I had to do several Safe Mode boots letting the computer "soak" in Safe Mode for up to an hour to give it time for some serious housekeeping
3) Only then would i try to restore the Fusion software connection between the two SSDs. That might work. See: How to fix a split Fusion Drive - Apple Support
4) Have the tech installl a proper blade SSD in the NVME slot. Example: OWC Aura Pro X2
Allan
