Large amount of data trimmed after running fstrim

Question

Each time after I restart my computer I run fstrim. And each time this is the output I receive:

emil@emil-Lenovo-G580 ~> sudo fstrim -v /
[sudo] password for emil: 
/: 84.2 GiB (90372820992 bytes) trimmed

I want to know is this normal?

What Ubuntu version are you running? fstrim should automatically run by default weekly. See here. — Terrance, Feb 03 '16 at 17:44
Ubuntu Gnome 15.10. And from what i have seen I don't think that my SSD is a supported model. Or I may be wrong. — Emil Zahariev, Feb 03 '16 at 17:47
It looks as though the weekly crontab job in 14.10 and newer is just running the same command you are but on all mounted filesystems. So my guess is that your drive is supported by it. — Terrance, Feb 03 '16 at 17:52
Also, this page might help shed a little more light on whether TRIM is supported or not. — Terrance, Feb 03 '16 at 17:54

score 4 · Accepted Answer · edited Nov 21 '23 at 17:26

Yes this is normal. If calling fstrim first time after reboot, size of all unused blocks is trimmed and reported. This is because "nobody" knows, which blocks are already trimmed before.

Calling fstrim again, it reports only recently freed blocks. This is, because the kernel keeps an eye to trimmed blocks. This information is lost, when rebooting. The behavior may change between versions ...

I've watched same behavior at Debian 8 (Jessie). And wondered, as you ;-)

Large amount of data trimmed after running fstrim

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