[LBo] Drive capacity puzzler

[Kevin B. O'Brien]

On Sat, 2007-02-03 at 09:01 +0100, Stefan Waidele wrote:
> tim schrieb:
> > [...]
> > Just a shot in the dark here, but I seem to remember something about 
> > ext3 using 5% for various overhead purposes.  I'll poke around a little 
> > later for my own knowledge, but 5% is close to 12 gig.  Of course if you 
> > formatted to reiser or something else that wouldn't apply.
> 
> This amount of space is not "overhead" (alone).
> It is reserved for the user root. Like that, the system remains 
> funtional when disks fill up and the "mere users" get disk-full messages 
> while vital services are still able to operate.
> 
> This is what `man mke2fs` sais about it:
> 
>    -m reserved-blocks-percentage
>         Specify the percentage of the filesystem blocks reserved for the
>         super-user.  This avoids fragmentation,  and  allows  root-owned
>         daemons,  such  as syslogd(8), to continue to function correctly
>         after non-privileged processes are prevented from writing to the
>         filesystem.  The default percentage is 5%.
> 
> Since ext3 is "ext2 on steroids" the same should be true.
> So, on big partitions, where 5% really matter (and especially if they 
> are mounted where no system-service has to write to), it will be wise to 
> specify that m-option.

Thanks for the information. I learn something new everyday. I guess it
is not anything to get panicky about, I was just puzzled by it.

-- 
Kevin B. O'Brien TANSTAAFL
zwilnik at zwilnik.com Linux User #333216
"Few things are harder to put up with than a good example." -- Mark
Twain