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.