SSD drives need to be TRIMed, i. e. they need to be told which blocks the OS considers as "unused" (i. e. from deleted files). Withouth this, the write speed on SSDs becomes slower over time.
fstrim-all detects which mounted partitions belong to drives that need/support trimming, and calls fstrim(1) on them.
It is meant to be called from cron. There is no output on success.
This only runs on Intel and Samsung SSDs as some SSDs with faulty firmware may encounter data loss problems when running fstrim under high I/O load (see e. g. https://launchpad.net/bugs/1259829). You can call fstrim-all with the --no-model-check option to disable the vendor check and run fstrim on all SSD drives.
Martin Pitt <email@example.com>