more user friendly filesystem space messages and checks

[Do]

Hello,

Now Monit send messages like this

> Subject: monit alert --  Resource limit matched root
> Resource limit matched Service root
> 
>         Date:        Wed, 29 Oct 2014 08:55:54
>         Action:      alert
>         Host:        db
>         Description: space usage 42075215 blocks matches resource limit 
> [space usage>26214355 blocks]

>From this, normal human can not understand at a glance how much resources is 
>matched: is it 1024 or 4096 blocks filesystem? I didn't set up check in 
>'blocks', I set them in GB.

So, I propose (feature request) to change message format to add used space size 
in GB, and free space in GB.

I usually add several checks for filesystem space so when space is filling I 
get several messages. Example, for 45G disk:

check filesystem root path /
  if space usage > 35 GB then alert
  if space usage > 40 GB then alert
  if space usage > 43 GB then alert
  if space usage > 44 GB then alert

But when there is 'blocks' I can not understand at glance how much space is 
filled and free, and how quickly admin need to react on the problem. You know, 
spae cleaning is not always easy task that can be done instantly, users may 
need to be notified, etc.

Additional request, why is 'space' controlled with 'usage' check and no 'free' 
check? To set check now, I need to view partition size (to see it's 45G or 
450G). (Also, when partition size changed need not forget to change monit 
rules.)

Without this restriction I could set up my style of checks w/o even looking at 
disk size. Proposed example,

check filesystem root path /
  if space free < 10 GB then alert
  if space free <  5 GB then alert
  if space free <  2 GB then alert
  if space free <  1 GB then alert

Thanks,
Don.