Perhaps my experience is anecdotal, but I have had horrible luck with the Tablo “recommended” Western Digital Elements external USB disk drive, namely the 5TB model (reference WDBU6Y0050BBK-WESN).
My operating environment is clean and cool, with surge protection (both local power strip and whole-home suppressor.)
In the span of 13 months, I have been through two drives that have totally failed. Both were brand new, and died without warning. When I connected the units to my PC, and ran the WD Dashboard app, the drive’s S.M.A.R.T. status was “poor” and I could not format the drives under Windows.
More telling is that WD has reduced the warranty period from three years to one year, which looks like they know they are selling crap.
My $0.02 is that you steer clear of this drive. YMMV.
Website still says 2 years, but 3 years still for the My Passport version (vs. the cheap Elements version).
Btw: I use the My Passport drives, but have upgraded over time and currently use their 4TB versions, having replace the older 3TB versions. How long did they last (the 3TB ones)? They are still alive, just not in use currently, Bought them when they came out, so they’re pretty old.
Edit 2: The drives are 24x7 on my Plex server. I use absolutely ancient Hitachi Touro drives on my Tablos.
I’ve been using Seagate Expansion 5TB Desktop External Hard Drives on my two Tablos. The oldest one since September 2015 and the other since November 2017. I realize that model is no longer available, but the two I own have served me well.
Perhaps they make some with 2.5" drives but I have shucked at least 4 Elements drives and they are all 3.5". They have all been reliable too. I can’t rate the enclosures so confidently since I don’t use them.