Thanks for the detailed assessment and recommendations.
Some clarifications:
1/ Actual SSD=8000GB (sorry, I missed one 0 in a hurry)
2/ Searching how to improve the umbrel performance I found the comments
and
recommending to add the line
reindex=1
to the umbrel-bitcoin.conf
I did it in the terminal using nano, saved it and restarted umbrelOS.
It began resyncing as it was a new installation, now finishing about 90%
However now after checking the content of the file “/home/umbrel/umbrel/app-data/bitcoin/data/bitcoin/umbrel-bitcoin.conf” I found that it does not have the line reindex=1 in it (!)
Having this result I do no understand your your comment #1 Re reindex=1:
supposing that I had saved the update umbrel-config correctly it should not have began reindexing, but it did.
Unless I mistakenly had no saved correctly (I had not checked before restarting being sure …)
How you see this situation?