A device is one thing with an address: a server, a switch, a firewall, a hypervisor, a web site or a mail domain. It sits in a group, holds the sensors that check it, and turns what those sensors find into one state. Where it fits in the estate is described under The Tree.
Adding a device
Select the group it belongs in under Setup, Configuration, and press Add. With a group selected,
the dialogue offers a device under it. Give it a name and its Hostname or address, which is
required. A device cannot sit directly on a site: use the site's Default group, or add a group first.
Settings
| Setting | What it does |
|---|---|
| Name | Required, and unique within its group. It is how the device appears on the dashboard and in every notification. |
| Icon | Optional. Opens a picker of vendor and generic equipment icons, such as a Cisco switch, a firewall or a cloud. The icon is shown beside the device in the configurator and on the dashboard. |
| Hostname or address | A DNS name or an IP address. Every sensor on the device targets it unless the sensor sets its own target override. A hostname is looked up on the probe making the check, so it must resolve from where the probe sits. |
| Notes | Free text, up to 500 characters, for whatever the next person needs to know: where it is, who looks after it, what depends on it. |
| Schedule | Inherited from above unless one is chosen. The device is polled only while its schedule is active, and a schedule set here overrides any above it. |
Nothing is stored until Save is pressed. Revert discards what has not been saved.
Sensors on a device
A device on its own checks nothing. Each check is a sensor added beneath it: a ping, a TCP port, a web request, an SNMP read, a database query. A device usually carries several, each answering one question, and it is normal for one of them to read the same response as another in a different way. Sensors that make an identical request share it, so five sensors reading five values from one document cost one request to the device. See Sensors.
Where one sensor should target something other than the device's address, a different port on another host or a whole URL for a web request, set its target override rather than adding a second device.
Device state
A device's state comes from its sensors, through its Rollup panel. Only sensors at OK, WARN or CRIT are counted; one that is UNKNOWN, STALE, paused, suspended or outside its schedule is left out. The number failing is then mapped to a state:
| Setting | Applies when | Default on a device |
|---|---|---|
ANY | Exactly one sensor is failing | CRIT |
SOME | More than one is failing, but not all | WARN |
ALL | Every counted sensor is failing | CRIT |
A CRIT mapping only gives CRIT when at least one of the failing sensors is itself CRIT. If they are all WARN, the device is WARN.
With the defaults, one critical sensor makes the device CRIT, but two critical sensors out of five make it WARN,
because two is SOME. For most devices, where any failed check means the device is in trouble, set
SOME to CRIT as well.
Minimum reporting is the number of sensors that must have an opinion before the device reaches a verdict; below it the device is UNKNOWN. A device with no sensors reporting is always UNKNOWN.
Clear Counts towards its parent's state on a sensor that is informative but not a fault in the device, a certificate expiry warning for instance. The sensor keeps its own state and its own notifications, and the device ignores it.
Templates
The Templates panel on a device copies sensors between devices.
- Save sensors as template copies every sensor on the device, as last saved, into one template. Addresses, credentials, probe groups and rollup settings are not copied. Review the result under Setup, Templates, and remove any sensor that should not travel.
- Apply adds every sensor in a chosen template to this device. A sensor whose name is already in use on the device is skipped. The new sensors have no probe groups, so nothing is polled until you open each one, choose its probe groups and save it.
A template is a copy, not a link. Changing it later does not change sensors already made from it. See Templates.
Credentials
Credentials held on a device reach every sensor of that type on it, and replace any held further up the tree. Hold a credential on the device when it differs from its neighbours, and on the group or site when it is shared. See Credentials.
Actions
The Actions panel binds notification rules to the device. A rule bound here with And everything beneath this device ticked covers the device and all of its sensors; unticked, it covers the device's own state only. Rules bound higher up the tree that reach the device are listed under the panel. See Actions.
Pausing and maintenance
Pause stops every sensor on the device being polled, and none of them counts towards an alarm, for a chosen period or indefinitely. Give a reason, such as a reboot or awaiting parts, and it is shown beside the device and recorded in the audit log. A timed pause lifts itself; Resume lifts it at once. For maintenance that happens on a timetable, a schedule is the better tool.
On the dashboard
Examine at the top of a device opens it on the dashboard. The Overview tab shows its path, state, address, its sensors with their states, and availability over the last 24 hours, 7 days and 30 days. The History tab charts its sensors on one time axis, with the device's state drawn as a band beneath.
Deleting
Delete removes the device together with all of its sensors and any credentials held on them. It cannot be undone. To keep the sensors for another device, save them as a template first.