Ed Light wrote:

HD Sentinel is following the life remaining SMART attribute, and as soon
as that's down to 99% it demotes the drive's Health rating.

But life remaining is not an error gauge. The life remaining will go
down and down with time.

I see it as a mistake in the software.

HD Sentinel still gives a green checkmark (in its own GUI and for the
overlay icon on the SSD drive in Windows Explorer) regarding the status
of my SSD although it says it is as 98%.

11 months after installing the SSD, HD Sentinel said there were 24
masking & redirects (the wear level count). It was a sudden jump.
Since then (6 months ago until today) there has been an average of 2
counts per month. I was surprised at the sudden jump one year later but
I don't remember if HD Sentinel was running all that time. I might've
done something 6 months ago to my hardware/software platform that go HD
Sentinel to record a big jump. With it progressing since then at 2
counts per month, a year's gradual degradation of 2 counts per month
over the 11 months would explain the value (but not why it was listed as
zero during that 11 months).

Oxide stress limits the number of erase/write cycles so eventually SSDs
wear out. That the SSD eventually catastrophically dies is because of
the technology upon which it is based. However, the life expectancy of
an SSD depends on how may erase/write cycles the manufacturer claims and
is only an estimate. The SSD could catastrophically die earlier or
later. The estimates by these monitoring software don't take into
account the differences in technologies used to produce NAND memories:
SLC, MLC, TLC, and other. I don't seen anything in HD Sentinel that
shows it detected the type of NAND technology employed by the SSD that
is in my computer. It's probably an attribute of the drive that is not
exposed to software query.

SSDs are often gauged to last about 10 years. Yeah, who wants to wait
until the drive catastrophically fails (with the increased slowness dur
to all the masking redirects) just to squeeze out every last minute of
usability. I figure to wait until HD Sentinel alerts me to a problem
with the drive or replace the SSD after 5-7 years barring failure before
then. They'll probably be a cheaper by then at far larger capacities.