Monitors Dell PowerVault ME5 series storage systems through the controller HTTPS management API. State for every object comes from the array's own health and status values, and every check has a configurable ruleset. Validated on the Dell PowerVault ME5024 in multiple production Checkmk environments.
Includes the following checks:

System health and management-controller redundancy
System performance: IOPS, throughput, and response time, each split into read and write, plus controller CPU and write cache use
Health alerts: unresolved critical and warning alerts, with the affected component, reason, and the array's recommended action
Controller health, failover, and cache policy
Controller firmware
Host ports: health, link status, speed, throughput, IOPS, response time, and queue depth
Enclosures: health, status, and power draw, one service per enclosure
Disk groups: RAID status, spares, and background jobs
Storage pools: capacity via the built-in Filesystem ruleset, with trend and forecast
Volumes: health, capacity, preferred-path ownership, throughput, IOPS, and cache hit ratios
Physical disks: health, SMART status, SSD life, temperature, power-on hours, throughput, IOPS, queue depth, and predictive error counters (media errors, bad blocks, block reassignments, spin-up retries, I/O timeouts, no-response events)
Power supplies
Fans
Temperature sensors, with state taken from the array's own per-sensor verdict and the built-in Temperature ruleset available for custom levels
Supercapacitor packs: charge, capacitance, internal resistance, and cell voltages, one service per controller
Voltage and current sensors
Unwritable cache
Snapshot protection: snapshot count, data, and newest snapshot age together with the schedule that creates them, with freshness and overdue alerting
Connected hosts

Version history:

1.2.2: fixed a false warning on the system health service where a healthy partner management controller was reported as not operational
1.2.0: added system performance, health alerts, enclosure, and supercapacitor checks, added volume and disk performance with cache hit ratios and predictive error counters, snapshot schedules are now reported with each volume's snapshots
1.1.0: added host port I/O statistics (throughput, IOPS, response time, and queue depth) to the host port check
1.0.0: initial release, system, controller, firmware, host port, disk group, pool, volume, disk, power supply, fan, temperature, sensor, unwritable cache, snapshot, and connected-host checks