Applies to SUSE Linux Enterprise Server 15 SP3

12 Storage enclosure LED utilities for MD software RAIDs #

Storage enclosure LED Monitoring utility (ledmon) and LED Control (ledctl) utility are Linux user space applications that use a broad range of interfaces and protocols to control storage enclosure LEDs. The primary usage is to visualize the status of Linux MD software RAID devices created with the mdadm utility. The ledmon daemon monitors the status of the drive array and updates the status of the drive LEDs. The ledctl utility allows you to set LED patterns for specified devices.

These LED utilities use the SGPIO (Serial General Purpose Input/Output) specification (Small Form Factor (SFF) 8485) and the SCSI Enclosure Services (SES) 2 protocol to control LEDs. They implement the International Blinking Pattern Interpretation (IBPI) patterns of the SFF-8489 specification for SGPIO. The IBPI defines how the SGPIO standards are interpreted as states for drives and slots on a backplane and how the backplane should visualize the states with LEDs.

Some storage enclosures do not adhere strictly to the SFF-8489 specification. An enclosure processor might accept an IBPI pattern but not blink the LEDs according to the SFF-8489 specification, or the processor might support only a limited number of the IBPI patterns.

LED management (AHCI) and SAF-TE protocols are not supported by the ledmon and ledctl utilities.

The ledmon and ledctl applications have been verified to work with Intel storage controllers such as the Intel AHCI controller and Intel SAS controller. They also support PCIe-SSD (solid-state drive) enclosure LEDs to control the storage enclosure status (OK, Fail, Rebuilding) LEDs of PCIe-SSD devices that are part of an MD software RAID volume. The applications might also work with the IBPI-compliant storage controllers of other vendors (especially SAS/SCSI controllers); however, other vendors’ controllers have not been tested.

ledmon and ledctl are part of the ledmon package, which is not installed by default. Run sudo zypper in ledmon to install it.

12.1 The storage enclosure LED monitor service #

The ledmon application is a daemon process that constantly monitors the state of MD software RAID devices or the state of block devices in a storage enclosure or drive bay. Only a single instance of the daemon should be running at a time. The ledmon daemon is part of Intel Enclosure LED Utilities.

The state is visualized on LEDs associated with each slot in a storage array enclosure or a drive bay. The application monitors all software RAID devices and visualizes their state. It does not provide a way to monitor only selected software RAID volumes.

The ledmon daemon supports two types of LED systems: A two-LED system (Activity LED and Status LED) and a three-LED system (Activity LED, Locate LED, and Fail LED). This tool has the highest priority when accessing the LEDs.

To start ledmon, enter

> sudo ledmon [options]

where [options] is one or more of the following:

Options for ledmon #

-c PATH , --confg=PATH

The configuration is read from ~/.ledctl or from /etc/ledcfg.conf if existing. Use this option to specify an alternative configuration file.

Currently this option has no effect, since support for configuration files has not been implemented yet. See man 5 ledctl.conf for details.

-l PATH , --log=PATH

Sets a path to local log file. If this user-defined file is specified, the global log file /var/log/ledmon.log is not used.

-t SECONDS , --interval=SECONDS

Sets the time interval between scans of sysfs. The value is given in seconds. The minimum is 5 seconds. The maximum is not specified.

--quiet, --error, --warning, --info, --debug, --all

Specifies the verbosity level. The level options are specified in the order of no information to the most information. Use the --quiet option for no logging. Use the --all option to log everything. If you specify more than one verbose option, the last option in the command applies.

-h , --help

Prints the command information to the console, then exits.

-v , --version

Displays version of ledmon and information about the license, then exits.

Note: Known issues

The ledmon daemon does not recognize the PFA (Predicted Failure Analysis) state from the SFF-8489 specification. Thus, the PFA pattern is not visualized.

12.2 The storage enclosure LED control application #

The Enclosure LED Application (ledctl) is a user space application that controls LEDs associated with each slot in a storage enclosure or a drive bay. The ledctl application is a part of Intel Enclosure LED Utilities.

When you issue the command, the LEDs of the specified devices are set to a specified pattern and all other LEDs are turned off. This application needs to be run with root privileges. Because the ledmon application has the highest priority when accessing LEDs, some patterns set by ledctl might have no effect if the ledmon daemon is running (except for the Locate pattern).

The ledctl application supports two types of LED systems: A two-LED system (Activity LED and Status LED) and a three-LED system (Activity LED, Fail LED, and Locate LED).

To start ledctl, enter

> sudo [options] PATTERN_NAME=list_of_devices

where [options] is one or more of the following:

-c PATH , --confg=PATH: Sets a path to local configuration file. If this option is specified, the global configuration file and user configuration file have no effect.
-l PATH , --log=PATH: Sets a path to local log file. If this user-defined file is specified, the global log file /var/log/ledmon.log is not used.
--quiet: Turns off all messages sent to stdout or stderr out. The messages are still logged to local file and the syslog facility.
-h , --help: Prints the command information to the console, then exits.
-v , --version: Displays version of ledctl and information about the license, then exits.

12.2.1 Pattern names #

The ledctl application accepts the following names for pattern_name argument, according to the SFF-8489 specification.

locate: Turns on the Locate LED associated with the specified devices or empty slots. This state is used to identify a slot or drive.
locate_off: Turns off the Locate LED associated with the specified devices or empty slots.
normal: Turns off the Status LED, Failure LED, and Locate LED associated with the specified devices.
off: Turns off only the Status LED and Failure LED associated with the specified devices.
ica , degraded: Visualizes the In a Critical Array pattern.
rebuild , rebuild_p: Visualizes the Rebuild pattern. This supports both of the rebuild states for compatibility and legacy reasons.
ifa , failed_array: Visualizes the In a Failed Array pattern.
hotspare: Visualizes the Hotspare pattern.
pfa: Visualizes the Predicted Failure Analysis pattern.
failure , disk_failed: Visualizes the Failure pattern.
ses_abort: SES-2 R/R ABORT
ses_rebuild: SES-2 REBUILD/REMAP
ses_ifa: SES-2 IN FAILED ARRAY
ses_ica: SES-2 IN CRITICAL ARRAY
ses_cons_check: SES-2 CONS CHECK
ses_hotspare: SES-2 HOTSPARE
ses_rsvd_dev: SES-2 RSVD DEVICE
ses_ok: SES-2 OK
ses_ident: SES-2 IDENT
ses_rm: SES-2 REMOVE
ses_insert: SES-2 INSERT
ses_missing: SES-2 MISSING
ses_dnr: SES-2 DO NOT REMOVE
ses_active: SES-2 ACTIVE
ses_enable_bb: SES-2 ENABLE BYP B
ses_enable_ba: SES-2 ENABLE BYP A
ses_devoff: SES-2 DEVICE OFF
ses_fault: SES-2 FAULT

When a non-SES-2 pattern is sent to a device in an enclosure, the pattern is automatically translated to the SCSI Enclosure Services (SES) 2 pattern as shown above.

Table 12.1: Translation between non-SES-2 patterns and SES-2 patterns #

Non-SES-2 Pattern	SES-2 Pattern
locate	ses_ident
locate_off	ses_ident
normal	ses_ok
off	ses_ok
ica	ses_ica
degraded	ses_ica
rebuild	ses_rebuild
rebuild_p	ses_rebuild
ifa	ses_ifa
failed_array	ses_ifa
hotspare	ses_hotspare
pfa	ses_rsvd_dev
failure	ses_fault
disk_failed	ses_fault

12.2.2 List of devices #

When you issue the ledctl command, the LEDs of the specified devices are set to the specified pattern and all other LEDs are turned off. The list of devices can be provided in one of two formats:

A list of devices separated by a comma and no spaces
A list in curly braces with devices separated by a space

If you specify multiple patterns in the same command, the device list for each pattern can use the same or different format. For examples that show the two list formats, see Section 12.2.3, “Examples”.

A device is a path to file in the /dev directory or in the /sys/block directory. The path can identify a block device, an MD software RAID device, or a container device. For a software RAID device or a container device, the reported LED state is set for all of the associated block devices.

The LEDs of devices listed in list_of_devices are set to the given pattern pattern_name and all other LEDs are turned off.

12.2.3 Examples #

To locate a single block device:

> sudo ledctl locate=/dev/sda

To turn off the Locate LED for a single block device:

> sudo ledctl locate_off=/dev/sda

To locate disks of an MD software RAID device and to set a rebuild pattern for two of its block devices at the same time:

> sudo ledctl locate=/dev/md127 rebuild={ /sys/block/sd[a-b] }

To turn off the Status LED and Failure LED for the specified devices:

> sudo ledctl off={ /dev/sda /dev/sdb }

To locate three block devices, run one of the following commands (both are equivalent):

> sudo ledctl locate=/dev/sda,/dev/sdb,/dev/sdc
> sudo ledctl locate={ /dev/sda /dev/sdb /dev/sdc }

12.3 More information #

See the following resources for details about the LED patterns and monitoring tools:

LEDMON open source project on GitHub.com