I'm running a fairly fresh and vanilla 10.10 install, built from scratch about a month ago on an Acer Aspire 5742 laptop. I use openbox as my window manager and run neither the KDE nor Gnome desktop stacks. I haven't yet figured out how to get the system to hibernate when low on battery power, so I get occasional power outages.
I've noticed that when my laptop switches over to battery power, my ext* partitions are remounted with the option
When I switch back to AC, there is another set of remounts with
This is apparent from entries in
Mar 31 14:48:48 gatsby kernel: [414710.189306] EXT4-fs (dm-0): re-mounted. Opts: errors=remount-ro,commit=600 Mar 31 14:48:48 gatsby kernel: [414710.324137] EXT4-fs (dm-1): re-mounted. Opts: commit=600 Mar 31 14:48:48 gatsby kernel: [414710.749636] EXT4-fs (dm-2): re-mounted. Opts: commit=600 Mar 31 16:35:58 gatsby kernel: [421128.882072] EXT4-fs (dm-0): re-mounted. Opts: errors=remount-ro,commit=0 Mar 31 16:35:58 gatsby kernel: [421129.083283] EXT4-fs (dm-1): re-mounted. Opts: commit=0 Mar 31 16:35:59 gatsby kernel: [421129.724136] EXT4-fs (dm-2): re-mounted. Opts: commit=0
mount manual explains the meaning of the
count option with respect to the ext3 filesystem thusly:
commit=nrsec Sync all data and metadata every nrsec seconds. The default value is 5 seconds. Zero means default.
What does this mean, exactly? It seems to imply that writes may be cached for up to 10 minutes. Does this mean that there could be filesystem corruption, or that some changes may go unsaved if my battery power runs out?