Check manual page of df

df

Author: Mathias Kettner

License: GPL

Distribution: official part of Check_MK

Supported Agents: Linux, Windows, AIX, Solaris, VMS

This check measures the usage of filesystems. The usage is checked against a warning and a critical level, which can be specified in numerous ways. Beware: on Linux and UNIX systems the filesystem might reserve a certain amount for root (typical is 5%). The reserved space is accounted for as used. This is consistant with the percentage-column in the output of df. So your filesystem might be at 100% in a situation where root still has 5% free space available.

As of version 1.1.9i9 Check_MK supports trends. This means that the df check is now able to compute the change of the used space over the time and can make a forecast into the future. It can estimate the point of time where the filesystem will be full.

In the default configuration the check will compute the trend based on the data of the last 24 hours. Similar like the CPU load this is done with a logarithmic average that weights the more recent time more than time farer away. Also data beyond the 24 hours will to some small degree be reflected in the computation. The advantage of this algorithm is a more precise prediction and a simpler implementation, which does not need any access to any RRDs or similar storage.

Please note, that when a filesystem is started being monitored, then the trend of the past is unknown and will be assumed to be zero. That means that it will take at least one trend range of time until the trend approximately reflects the reality.

Item

The mount point of the filesystem (UNIX) or the drive letter in upper case followed by a colon (Windows).

Check parameters

Parameter	Type	Description
parameters	dict	This check supports two types of parameters. The new version supports trends and is a dictionary with the following keys: "levels": Warning and critical level of filesystem usage in percentages of the filesystem size. The default is (80, 90). "magic": The magic number, which scales the levels according to the filesystem size. Default is a factor of 1.0, which does no adaptation. A factor less than 1.0 raises the levels for large filesystems and lowers them for small ones. Please look at online documentation for more details about the magic factor. "magic_normsize": Norm size of a filesystem for the magic computation. The default for this is 20. It is measured in GB. "levels_low": When applying the magic factor the warn/crit levels will never drop below these numbers. The is preset to (50,60). "trend_range": The time range over that trends are computed. This is in hours and preset to 24 (i.e. one day). If you set this to None then trend computing is disabled and the check outputs only one performance data value. "trend_mb": A pair of numbers specifying the maximum number of megabytes the usage is allowed to grow within the time range if not triggering warning/critical. If you set this to (10,20) then the check will warn if the size grows by more than 10 MB per trend_range hours and critical if it grows more than 20 MB. Per default no levels are applied. "trend_perc": This is similar to trend_mb but here you specify the allowed growth in percentages of the filesystem size. Fractional values are allowed. This may be used in parallel with trend_mb. "trend_timeleft": A pair of numbers that specifies the minimum hours of time left until the filesystem gets full. If you set this to (48,24) then the check will warn if the estimated time until the disk is full is 48 hours or less. It will get critical if only 24 hours are assumed to be left. "trend_perfdata": If this is set to True, then the check will output two further performance data values: the current growth and the trend. It is still possible to specify a pair or triple of numbers instead of a dictionary:
warning	int	The percentage of used space that triggers WARNING state
critical	int	The percentage of used space that triggers CRITICAL space
magic_factor	float	Optional: Magic factor that adapts the levels according to the size of the filesystem. Default is a factor of 1.0, which does no adaptation. A factor less than 1.0 raises the levels for large filesystems and lowers them for small ones. Please look at online documentation for more details about the magic factor.

Performance data

One or three values: The first value is the used space of the filesystem in MB. Also the minimum (0 MB), maximum (size of the filesystem) and the warning and critical levels in MB are provided. If you set the parameter "trend_perfdata" : True, then two additional values are output: the change of the usage in MB per range since the last check (e.g. in MB per 24 hours) and the averaged change (so called trend), also in MB per range. Please note, that as of version 1.1.11i3, performance data for trends is enabled per default. You can globally disable that in main.mk with filesystem_default_levels["trend_perfdata"] = False.

Please note, that - until you use the storage type MULTIPLE in PNP4Nagios - changing the parameter "trend_perfdata" will stop all updates to your existing filesystem RRDs. You need either to delete or convert your RRDs if you want to change.

Inventory

df supports inventory. All filesystem the agent reports will be inventorized except mount points listed in inventory_df_exclude_mountpoints and filesystem types listed in inventory_df_exclude_fs. The Windows agent only reports fixed disks. The Linux agent reports filesystems that have a size and are not of type smbfs, tmpfs, cifs or nfs.

Configuration variables

Variable	Type	Description
inventory_df_exclude_fs	list of strings	Lists of filesystem types to exclude from inventory
inventory_df_exclude_mountpoints	list of strings	List of mount points to exclude from inventory
filesystem_default_levels:		Default levels for filesystem detected by inventory. This variable is preset to { "levels" : (80, 90), "magic_normsize" : 20, "levels_low" : (50, 60), "trend_range" : 24 }

Examples

# Set default levels for all filesystems to 90/95 (simple way)
filesystem_default_levels = (90, 95)

# alternative: Set default levels via new dictionary method:
filesystem_default_levels = {
   "levels"         : (80, 90),  # levels in percent
   "magic"          : 0.8,       # magic factor
   "magic_normsize" : 20,        # normsize in GB
   "levels_low"     : (50, 60),  # magic never lowers levels below this (percent)
   "trend_range"    : 48,        # hours
   "trend_mb"       : (10, 20),  # MB of change during trend_range
   "trend_perc"     : (1, 2),    # Percent change during trend_range
   "trend_timeleft" : (72, 48),  # run time left in hours until full
   "trend_perfdata" : False      # no performance data for trends
}

# alternative[2]: Just change the default partially
filesystem_default_levels["magic"] = 0.8

# Disable trend performance data (beware of exsting RRDs)
filesystem_default_levels["trend_perfdata"] = False

# Override warning/critical levels for all checks where
# levels are "filesystem_default_levels"
check_parameters = [
   # Hosts with tag "vms" get 85/95
   ( (85, 95), ["vms"], ALL_HOSTS, [ "fs_" ] ),
   # all /sapdata partitions will never be critical
   ( (101, 101), ALL_HOSTS, [ "fs_/sapdata$" ] ),
   # Partitions below "/var" get 80/90 with magic factor 0.5
   ( (80, 90, 0.5), ALL_HOSTS, [ "fs_/var" ] ),
   # /usr and /opt on hosts zlnx01 and zlnx02
   ( (98, 99), [ "zlnx01", "zlnx02" ], [ "fs_/usr$", "fs_/opt$" ] ),
   # All filesystems on clusters get 80/95
   ( (80, 95), ALL_CLUSTERS, [ "fs_" ] ),
   # Complex parameters in dictionary form
   ( {"levels":(80,90), "trend_range":48, "trend_mb":(20,40)},
     [ "windows" ], ALL_HOSTS, [ "fs_" ]),
]

# Exclude temporary backup from inventory
inventory_df_exclude_mountpoints = [ "/mnt/backup" ]

# Exclude certain filesystems from being inventorized at all
inventory_df_exclude_fs = [ "iso9660", "romfs" ]