terryc - 05.12.23, 04:18:40 CET:
> > I put a Western Digital Black NVME 500G drive in my desktop system
> > and ran it for about 3 years. At the end it had 65% life left which
> > surprised me as my desktop doesn't do an awful lot of disk writing or
> > even reading.
>
> How did you determine this lifetime?
>
> I have a couple of systems with SSDs. One is /Everything and the other
> has two under / and /home. They were rolled out about two years ago.
>
> FWIW HowToGeek on testing SSDs claims Blackblaze claims SSD. will
> outlast HDDs. Samne rate of failure under 3 years and HDDs start
> failing after 54 years, but SSDs go on further

smartctl -x on a Samsung 980 Pro 2 TB SSD which is about 2 years
meanwhile, in daily usage:

Available Spare:                    100%
Available Spare Threshold:          10%
Percentage Used:                    1%
[…]
Data Units Read:                    261.509.276 [133 TB]
Data Units Written:                 73.925.789 [37,8 TB]

Especially in case you leave some space free, use trimming either by
fstrim or in case its cleanly supported by your SSD with discard mount
option, preferably async discard like in XFS or with discard=async in
BTRFS, good SSDs should last a very long time. Of course you can still use
"noatime" and using a new enough kernel also "lazytime". I just use
"lazytime" nowadays on my laptops. Together with sysctl setting

vm.dirtytime_expire_seconds = 7200

so it updates every 2 hours instead of AFAIR 24 hours in case of no other
activity triggering an update.

"Percentage Used: 1%" basically means 1% of the usable lifetime has
expired by vendor estimate:

> The wear level is given by the “Percentage Used” field, which is
> specified as (page 184):
>
> Percentage Used: Contains a vendor specific estimate of the percentage
> of NVM subsystem life used based on the actual usage and the
> manufacturer’s prediction of NVM life. A value of 100 indicates that
> the estimated endurance of the NVM in the NVM subsystem has been
> consumed, but may not indicate an NVM subsystem failure. The value is
> allowed to exceed 100. Percentages greater than 254 shall be
> represented as 255. This value shall be updated once per power-on hour
> (when the controller is not in a sleep state).

https://unix.stackexchange.com/questions/652623/how-to-evaluate-the-wear-level-of-a-nvme-ssd

Due to the way flash works the best way to keep them alive for a long time
is: Use a bigger capacity than you need and leave some space free. With
LVM I usually just do not allocate about 10-20% of the capacity. But even
if you allocate all of the space for filesystems… I am not worried about
SSD lifetime regarding wear leveling. Not at all. I did not see any of my
SSDs failing due to wear leveling issues. Not even close. Even with write
heavy systems like a Plasma desktop with PostgreSQL based Akonadi and
desktop search and all kinds of writing around here and there.

On any of my laptops I would not even consider putting in a hard disk to
save SSD lifetime. And if I had a desktop computer, I probably would not
do either. I love totally quiet systems, happily using zcfan on my
ThinkPad laptops. And since I use SSDs I noticed how loud even 2,5 inch
hard disks can be. I still use those for backup purposes, cause even with
today's low SSD prices for backups I prefer even cheaper hard disks. But a
12 TB 3,5 inch hard disk monster in my living area or office? Not even a
chance.

Ciao,
--
Martin