In Linux Logical Volume Management (LVM), logical volumes (LVs) can span across multiple physical volumes (PVs) within the same volume group (VG). This flexibility is great for storage management, but sometimes you need to know exactly which PVs contain the extents for a particular LV.

Here are the key commands to identify PV allocation for LVs:

# Display PV allocation for all LVs in a VG
sudo pvdisplay -m

# Show detailed LV segment information
sudo lvdisplay -m /dev/vg_name/lv_name

Let's walk through a real-world scenario with a VG named 'datavg' containing two PVs:

$ sudo vgdisplay datavg
  --- Volume group ---
  VG Name               datavg
  System ID             
  Format                lvm2
  VG Size               1.99 TiB
  PE Size               4.00 MiB
  Total PE              522237
  Alloc PE / Size       522237 / 1.99 TiB
  Free  PE / Size       0 / 0   
  VG UUID               abc123-xzy-789

Now let's examine the PV allocation:

$ sudo pvdisplay -m
  --- Physical volume ---
  PV Name               /dev/sdb1
  VG Name               datavg
  PV Size               1.00 TiB / not usable 3.00 MiB
  Allocatable           yes 
  PE Size               4.00 MiB
  Total PE              262144
  Free PE               0
  Allocated PE          262144
  PV UUID               def456-uvw-012

  --- Physical Segments ---
  Physical extent 0 to 262143:
    Logical volume /dev/datavg/lv_data
    Logical extents 0 to 262143

  --- Physical volume ---
  PV Name               /dev/sdc1
  VG Name               datavg
  PV Size               1023.99 GiB / not usable 3.00 MiB
  Allocatable           yes 
  PE Size               4.00 MiB
  Total PE              262143
  Free PE               0
  Allocated PE          262143
  PV UUID               ghi789-rst-345

  --- Physical Segments ---
  Physical extent 0 to 262142:
    Logical volume /dev/datavg/lv_data
    Logical extents 262144 to 524287

The output shows that our 'lv_data' LV spans both PVs:

• /dev/sdb1 contains logical extents 0-262143
• /dev/sdc1 contains logical extents 262144-524287

For scripting purposes, you can extract specific information:

# List which PVs an LV uses
sudo lvs -o +devices /dev/vg_name/lv_name

# Get PV allocation percentages
sudo pvs -o +pv_used,pv_used_percent

If you encounter issues:

• Ensure you have root privileges (or sudo access)
• Verify the LV is not inactive (use lvchange -a y to activate)
• Check for LVM filter restrictions in /etc/lvm/lvm.conf

When working with Logical Volume Manager (LVM), a common administrative task is determining which physical volumes (PVs) actually store the data for a given logical volume (LV). This becomes particularly important when:

• Planning storage migrations
• Troubleshooting performance issues
• Preparing for hardware maintenance
• Optimizing storage allocation

The most straightforward method uses the lvs command with specific parameters:

# lvs -o +devices
  LV     VG     Attr       LSize   Devices             
  lv_root vg_sys -wi-ao---- 50.00g /dev/sda2(0)        
  lv_home vg_sys -wi-ao---- 200.00g /dev/sda2(12288),/dev/sdb1(0)

For a more comprehensive view, combine multiple LVM commands:

# pvdisplay -m
  --- Physical volume ---
  PV Name               /dev/sda2
  VG Name               vg_system
  PV Size               465.76 GiB
  Allocatable           yes
  PE Size               4.00 MiB
  Total PE              119234
  Free PE               5324
  Allocated PE          113910
  PV UUID               abc123-xzy-789

  --- Physical Segments ---
  Physical extent 0 to 12287:
    Logical volume /dev/vg_system/lv_root
    Logical extents 0 to 12287
  Physical extent 12288 to 119233:
    Logical volume /dev/vg_system/lv_home
    Logical extents 0 to 106945

For automated environments, here's a bash script that generates a PV-LV mapping report:

#!/bin/bash
for vg in $(vgs --noheadings -o vg_name); do
  echo "Volume Group: $vg"
  lvs --noheadings -o lv_name,devices $vg | while read lv devices; do
    echo "  LV: $lv"
    echo "$devices" | tr ',' '\n' | sed 's/^/    /'
  done
  echo
done

When LVs span multiple PVs, you can check segment distribution:

# lvdisplay --maps vg_name/lv_name
  --- Logical volume ---
  LV Path                /dev/vg_data/lv_archive
  LV Name                lv_archive
  VG Name                vg_data
  LV UUID                xyz789-123-abc
  LV Write Access        read/write
  LV Creation host       server1
  
  --- Segments ---
  Logical extents 0 to 51199:
    Type                linear
    Physical volume     /dev/sdc1
    Physical extents    0 to 51199

  Logical extents 51200 to 102399:
    Type                linear
    Physical volume     /dev/sdd1
    Physical extents    0 to 51199

For RHEL/CentOS systems, the lvseg command provides concise output:

# lvseg -v vg_application
  LV             LE   PE   PV             PE Ranges
  lv_app_data    1024 1024 /dev/sde1      0-1023
  lv_app_logs    512  512  /dev/sdf1      0-511
  lv_app_cache   256  256  /dev/sde1      1024-1279
  lv_app_cache   256  256  /dev/sdf1      512-767