node_exporter/text_collector_examples/md_info.sh

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#!/usr/bin/env bash
set -eu
for MD_DEVICE in /dev/md/*; do
# Subshell to avoid eval'd variables from leaking between iterations
(
# Resolve symlink to discover device, e.g. /dev/md127
MD_DEVICE_NUM=$(readlink -f "${MD_DEVICE}")
# Remove /dev/ prefix
MD_DEVICE_NUM=${MD_DEVICE_NUM#/dev/}
MD_DEVICE=${MD_DEVICE#/dev/md/}
# Query sysfs for info about md device
SYSFS_BASE="/sys/devices/virtual/block/${MD_DEVICE_NUM}/md"
MD_LAYOUT=$(cat "${SYSFS_BASE}/layout")
MD_LEVEL=$(cat "${SYSFS_BASE}/level")
MD_METADATA_VERSION=$(cat "${SYSFS_BASE}/metadata_version")
MD_NUM_RAID_DISKS=$(cat "${SYSFS_BASE}/raid_disks")
# Remove 'raid' prefix from RAID level
MD_LEVEL=${MD_LEVEL#raid}
# Output disk metrics
for RAID_DISK in ${SYSFS_BASE}/rd[0-9]*; do
DISK=$(readlink -f "${RAID_DISK}/block")
DISK_DEVICE=$(basename "${DISK}")
RAID_DISK_DEVICE=$(basename "${RAID_DISK}")
RAID_DISK_INDEX=${RAID_DISK_DEVICE#rd}
RAID_DISK_STATE=$(cat "${RAID_DISK}/state")
DISK_SET=""
# Determine disk set using logic from mdadm: https://github.com/neilbrown/mdadm/commit/2c096ebe4b
if [[ ${RAID_DISK_STATE} == "in_sync" && ${MD_LEVEL} == 10 && $((MD_LAYOUT & ~0x1ffff)) ]]; then
NEAR_COPIES=$((MD_LAYOUT & 0xff))
FAR_COPIES=$(((MD_LAYOUT >> 8) & 0xff))
COPIES=$((NEAR_COPIES * FAR_COPIES))
if [[ $((MD_NUM_RAID_DISKS % COPIES == 0)) && $((COPIES <= 26)) ]]; then
DISK_SET=$((RAID_DISK_INDEX % COPIES))
fi
fi
echo -n "node_md_disk_info{disk_device=\"${DISK_DEVICE}\", md_device=\"${MD_DEVICE_NUM}\""
if [[ -n ${DISK_SET} ]]; then
SET_LETTERS=({A..Z})
echo -n ", md_set=\"${SET_LETTERS[${DISK_SET}]}\""
fi
echo "} 1"
done
# Output RAID array metrics
# NOTE: Metadata version is a label rather than a separate metric because the version can be a string
echo "node_md_info{md_device=\"${MD_DEVICE_NUM}\", md_name=\"${MD_DEVICE}\", raid_level=\"${MD_LEVEL}\", md_metadata_version=\"${MD_METADATA_VERSION}\"} 1"
)
done