When working with LVM in Linux, you'll often encounter two different naming schemes for the same block devices:

# What you see in mount:
/dev/mapper/VolGroup00-LogVol00

# What appears in iostat:
dm-0

The most straightforward method uses dmsetup:

sudo dmsetup ls --tree
VolGroup00-LogVol00 (253:0)
 └─ (8:2)

This shows the mapping between the human-readable name and the device mapper number (253:0 here corresponds to dm-0).

For scripting purposes, this one-liner creates a complete mapping:

ls -l /dev/mapper/* | grep -v control | awk '{print $9, $10}' | \
while read -r link target; do \
  dev=$(readlink -f "$link"); \
  echo "$(basename "$link") -> $(basename "$dev")"; \
done

To make iostat show friendly names:

iostat -xN 1

The -N flag displays LVM names instead of dm-* names.

For systems where device numbers might change, use UUIDs:

blkid /dev/mapper/VolGroup00-LogVol00
/dev/mapper/VolGroup00-LogVol00: UUID="5a3f4e1d..." TYPE="ext4"

Here's how I debugged a performance issue:

# iostat shows heavy IO on dm-3
iostat -x 1

# Find which LVM volume this is
ls -l /dev/dm-3
lrwxrwxrwx 1 root root 4 Jan 10 10:00 /dev/dm-3 -> ../dm-3

# Get major:minor numbers
ls -l /dev/dm-3
brw-rw---- 1 root disk 253, 3 Jan 10 10:00 /dev/dm-3

# Cross-reference with dmsetup
dmsetup info -c -o name,major,minor | grep "253,.*3"
backup_vg-backup_lv  253 3

Another approach using LVM tools:

lvdisplay -m | grep -A1 "Logical volume" | \
awk '/LV Name/{name=$3} /Block device/{print name, $3}'

---

When working with LVM-managed storage in Linux, you'll often encounter two different naming schemes:

# Mount output shows LVM logical volume names
/dev/mapper/VolGroup00-LogVol00 on / type ext4 (rw)

# iostat shows kernel device mapper names
Device:            tps    kB_read/s    kB_wrote/s
dm-0             10.21       102.34        205.67
dm-1              5.43        51.29         89.32

Method 1: Using dmsetup

The most reliable way to map dm-X devices to LVM names:

# List all device mapper names with their major:minor numbers
$ sudo dmsetup ls --tree
VolGroup00-LogVol00 (253:0)
└─ (8:2)
VolGroup00-LogVol01 (253:1)
└─ (8:2)

# Then check iostat -x output to match major:minor numbers
$ ls -l /dev/dm-*
brw-rw---- 1 root disk 253, 0 Jan 15 10:30 /dev/dm-0
brw-rw---- 1 root disk 253, 1 Jan 15 10:30 /dev/dm-1

Method 2: Using lsblk

A more visual approach with hierarchical display:

$ lsblk -o NAME,KNAME,MAJ:MIN,RM,SIZE,RO,FSTYPE,MOUNTPOINT
NAME                      KNAME     MAJ:MIN RM   SIZE RO FSTYPE MOUNTPOINT
sda                       sda        8:0    0   500G  0
├─sda1                    sda1       8:1    0     1G  0 ext4   /boot
└─sda2                    sda2       8:2    0   499G  0
  ├─VolGroup00-LogVol00   dm-0     253:0    0   400G  0 ext4   /
  └─VolGroup00-LogVol01   dm-1     253:1    0    99G  0 ext4   /home

Method 3: Using udevadm

For detailed low-level device information:

$ udevadm info -q all -n /dev/dm-0 | grep DM_NAME
E: DM_NAME=VolGroup00-LogVol00

For frequent use, create a mapping script:

#!/bin/bash
for device in $(ls /dev/dm-* | sort); do
    dev_name=$(basename $device)
    vol_name=$(sudo dmsetup info -c --noheadings -o name $dev_name)
    echo "$dev_name -> /dev/mapper/$vol_name"
done

Sample output:

dm-0 -> /dev/mapper/VolGroup00-LogVol00
dm-1 -> /dev/mapper/VolGroup00-LogVol01

Note that dm-X numbering isn't persistent across reboots. For monitoring scripts, always use:

• /dev/mapper/ names (persistent)
• Major:minor numbers (consistent until configuration changes)
• UUIDs (most persistent but requires filesystem)

Combine these techniques to monitor specific LVM volumes:

# Get all dm-X devices for your volume group
$ vgdisplay -v VolGroup00 | grep "Logical volume" -A1 | grep "dm-"

# Then monitor specific LV:
$ iostat -x $(dmsetup info -c --noheadings -o name dm-0) 1 5