Is it necessary to run e2fsck?

[Bohlendach]

I have olegs fw 1.9.2.7-8 and a USB harddisk connected 120 GB (3 partitions: 512 mb SWAP, 1gb and the rest). I primarily use it as backup and from time to time I use transmission.

I have tried to run e2fsck, but I get: WARNING!!! Running e2fsck on a mounted filesystem may cause SEVERE filesystem damage.

Questions:

Is it necessary to run e2fsck?

If yes, when, on which partitions and how?

I do not want to damage my harddisk.

[al37919]

e2fsck _should_not_ be run on mounted partitions. Unmount first. Otherwise run it during the router's start-up when the partitions are not yet mounted. Se, e.g.: http://wl500g.info/showthread.php?t=13785

[wpte]

I did it some times and every time I get this "7.5% non-contiguous" wich means that something is broken...
however, when I check it in gnome partition manager on puppy linux, no errors at all:confused:

I like what al37919 does with the post-shutdown, I already did something similar myself, but it only did it for programs that need a proper shutdown:)