I did not answer your question because i dont know the limit of the device (u9h) for external hdd.
MINIX officially support HDD's up to 2.5 TB with the U9-H. (Obviously end users have reported successfully using much larger drives themselves
.)
I'm so deep in externals lol! Honestly my wife and are so use to the externals, we will never go NAS. We have them labeled pretty good and its quite easy to switch.
I thought i could only use 4TB. I will only buy Western digital HD's. Interesting to know i can buy a 6 gig or even an 8 gig...
Read the above regarding the maximum size MINIX "officially" support with the U9-H
.
Personally, I had the Seagate & WD 8TB external HDD's working fine myself & you have the 4TB WD working fine too, but that's not a guarantee that a 6TB will work (if you follow?).
Having said that, I think it would be a reasonably safe assumption that if the 8TB Seagate, & the 4TB & 8TB WD external HDD's work fine with the U9-H, the 6TB versions probably will as well
. (Purchase from Amazon lol, if a 6TB doesn't work for any reason you can immediately return it no questions asked
.)
Fair enough if your current system of multiple HDD's is working for you
. I'm not going to try to flog you NAS or endlessly preach to others to convert lol
.
Obviously I was in a similar situation to you myself & based upon the capacity of my current NAS I would have ended up with at least 12 x 8TB external HDD's by now lol.
The other major factor for me to swap over to NAS along with the other considerations is that using RAID/parity on the NAS gives you a backup of all data if an HDD in the array should fail. If an external HDD dies you can wave goodbye to X TB's of data
.
Whatever works best for your situation/circumstances at the end of the day.
Enjoy
.