Re: How does monit check disk usage technically?

[Sergio Trejo]

On 8/31/07, Martin Pala <address@hidden> wrote:

Monit uses the system's statfs API.

The filesystem usually have some part reserved for superuser (ca. 5% on
other unixes).

What's your supposed disk usage (difference between monit and other
tools report?)

Thanks,
Martin

Hello Martin,

On Mac OS X I have used the command-line too, df with the -k option which option then uses 1024-byte (1-Kbyte) blocks rather than the default (according to the man page):

According to df -k, I'm getting disc usage such as (sorry the format of the text below might not be tabbed correctly in the copy-and-paste):

Filesystem              1K-blocks     Used     Avail Capacity

/dev/disk1s1             79707352 13020876  66430476    16%
/dev/disk2              243138528  1617544 241520984     1%
/dev/disk5s1             53346304  5160580  48185724    10%
/dev/disk5s3             12451840  9073000   3378840    73%
/dev/disk5s5             12451840  9057320   3394520    73%
/dev/disk5s7            209584128 55447560 154136568    26%
/dev/disk5s9            187109360    65124 187044236     0%

So from df -k, none of my discs are exceeding the 75% threshold that I have used in the monit configuration file. Yet monit is saying that all of my discs (listed above) are at 100%. Such as this report (note: I have multiple thresholds in my monit configuration file starting at 75%, 85%, 90% and 99% which are all set to send me alerts by monit):

[ Aug 31 17:30:35] error    : 'SomeDiscName' space usage 100.0% matches resource limit [space usage>75.0%]

I wonder if there is something that could be added in the monit source code for a new version that could check to see if the file system is Apple's HFS+ and if so, maybe a different approach needs to be taken for obtaining the disc usage information?

By the way, I also have similar thresholds for inode usage for all of my discs (75%, 80%, etc.) and monit did not alert me about inodes exceeding the thresholds so maybe the method used for inode counting (used v.s . total) works just fine for HFS+ disc devices?

Please let me know if I can do any further testing / feedback.

Cheers,

Sergio

 

Sergio Trejo wrote:
> Hello again,
>
> I just edited a monit configuration file which monitors devices (disc
> volumes) on my Mac server running Mac OS X 10.4.10. The discs attached
> are the HFS+ file system types (standard for Apple).
>
> My device entry in the monit configuration file looks like this:
>
> check device SomeDiscName with path /dev/disk1
>      if space usage > 90% then alert
>
> What's interesting is that I'm getting alerts for my device checks even
> though I know for sure (using some of the BSD tools that Apple bundles
> with Mac OS X) that my disc space is much much less than 90% usage.
> Monit is sending me alerts in email that look like this:
>
>     SomeDiscName Resource limit matched at Fri, 31 Aug 2007 17:30:35 +0000
>
>
> And the corresponding log entry looks like this:
>
>     [ Aug 31 17:30:35] error    : 'SomeDiscName' space usage 100.0%
>     matches resource limit [space usage>90.0%]
>
>
> Should I not be using monit for monitoring disc device space use and/or
> inode use on Mac systems with HFS+ file system types?
>
> Thanks again,
>
> Serg
>
>
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