banshee/storage-collection/storage/truenas/snmp/core/pools

Pools of a TrueNAS CORE, by SNMP

Returns, for each ZFS pool of a TrueNAS CORE, its health, its used space, its free space and its size. Five watches are offered, each one set on the probe.

Versions

Written for FREENAS-MIB, revision 2020-05-28: the MIB of TrueNAS CORE 12 and 13, and of TrueNAS SCALE up to 22.12. TrueNAS SCALE 23.10 and later serve TRUENAS-MIB, whose pool table has other columns (the health third, as a word, and no size): read it with storage/truenas/snmp/scale/pools. Hence the folder core.

How it works

The collector reads one table of FREENAS-MIB, zpoolTable (1.3.6.1.4.1.50536.1.1.1):

Column	OID	Read as
`zpoolDescr`	`.1.2`	the pool's name, the instance
`zpoolAllocationUnits`	`.1.3`	bytes per unit
`zpoolSize`, `zpoolUsed`, `zpoolAvailable`	`.1.4` to `.1.6`	counts of units
`zpoolHealth`	`.1.7`	`online` (0), `degraded` (1), `faulted` (2), `offline` (3), `unavail` (4), `removed` (5)

The used space is used over used plus available, as zpool list shows its capacity.
A pool whose row has no size shows its health only.
The collector only reads: SNMP sends nothing but reads.

Prerequisites

The SNMP service of TrueNAS enabled (Services, SNMP), reachable from the poller (UDP 161), its access restricted to the poller.
Read-only access, SNMPv2c or SNMPv3, set on the host or one of its folders (protocol:snmp:* variables).

Outputs

Name	Label	Unit	Per instance
`health`	Health	—	yes, per pool
`used-percent`	Used space	%	yes, per pool
`free`	Free space	GiB	yes, per pool
`size`	Size	GiB	yes, per pool

Watches

Name	Title	Kind	Defaults	Checked by default
`unhealthy`	Pool not online	expected value, on `health`	warning when the health is anything but `online`	yes
`failed`	Pool failed	state to avoid, on `health`	critical on `faulted`, `unavail`, `removed`	yes
`used`	Used space	above a threshold, on `used-percent`	warning above 80 %, critical above 90 %	yes
`full-soon`	Full within a week	above a threshold, on `used-percent`	warning above 99 %, ahead 7 d	yes
`missing`	Pool missing	expected instances, on `health`	no pool named: it raises nothing until names are set on the probe	no

Limits

An agent that serves no pool (a SCALE 23.10 or later, a view without the branch 1.3.6.1.4.1.50536) stops the collector misconfigured, and says which collector to use.
Not checked against a TrueNAS: the OIDs are those of the MIB file of TrueNAS 13.0 (FREENAS-MIB.txt, middleware branch truenas/13.0-stable).