[CentOS] df to get total disk usage on all filesystems?

Thu Aug 14 22:23:24 UTC 2008
Nifty Cluster Mitch <niftycluster at niftyegg.com>

On Thu, Aug 14, 2008 at 02:45:43PM -0700, MHR wrote:
> On Thu, Aug 14, 2008 at 2:36 PM, Nifty Cluster Mitch
> <niftycluster at niftyegg.com> wrote:
> >
> > $ cat /tmp/checkspace
> > #!/bin/bash
> > df -Pkl > /tmp/checkingdiskspce
> > echo -e "\nInput is:"
> > cat /tmp/checkingdiskspce
> > echo -e "\nAdding up the bits"
> > cat /tmp/checkingdiskspce | awk '/^\/dev\// { used += $3/1024 } END { printf("%d Mb Used\n", used)} '
> This is simpler (and does not involve as many execs & forks) as:
> awk '/^\/dev\// { used += $3/1024 } END { printf("%d Mb Used\n",
> used)} ' /tmp/checkingdiskspce

True, yet if the goal is "df | awk" with no tmp file at all the final
edit and cleanup is cleaner.  If the goal is to present the result of
"df" combined with a bottom line summary your line may be better.

I did notice in this discussion that no one looked at inode counts.
A filesystem might be "full" for want of an inode....  I cannot
recall if ext[23] will allocate additional inodes dynamically like xfs will.
Since xfs will allocate them but not delete then a run-away could
cause a lot to be allocated on xfs confusing space use.

Other interesting system admin topics not addressed includes sparse files.  For some
knowing about sparse files is important for backup tools.   Also  allocation block size
mismatch to average file sizes.   Lots of small byte count files on a large allocation
block causes book keeping confusion. Some tiny files never allocate a block as the inode
can contain some data on some filesystems.

Just looked at the mk2fs man page the -N, -i and -I flags answer my question
about dynamic inode allocation (Answer=no). 

	T o m  M i t c h e l l 
	Got a great hat... now what.