pvdisplay Command Linux: Complete Guide to Physical Volume Information Display

The pvdisplay command is an essential tool in Linux for displaying detailed information about Physical Volumes (PVs) in Logical Volume Manager (LVM) configurations. This comprehensive guide will walk you through everything you need to know about using pvdisplay effectively for storage management and system administration.

What is pvdisplay Command?

The pvdisplay command displays attributes of one or more physical volumes in an LVM setup. Physical volumes are the underlying storage devices (like hard drives or partitions) that LVM uses to create volume groups and logical volumes. This command provides crucial information about disk usage, allocation, and configuration details.

Basic Syntax

pvdisplay [options] [physical_volume_path]

When executed without any arguments, pvdisplay shows information for all physical volumes on the system.

Common Options and Parameters

Essential Options

Basic Usage Examples

Display All Physical Volumes

sudo pvdisplay

Sample Output:

  --- Physical volume ---
  PV Name               /dev/sda2
  VG Name               ubuntu-vg
  PV Size               <19.00 GiB / not usable 0   
  Allocatable           yes 
  PE Size               4.00 MiB
  Total PE              4863
  Free PE               1279
  Allocated PE          3584
  PV UUID               abc123-def4-5678-90ab-cdef12345678

  --- Physical volume ---
  PV Name               /dev/sdb1
  VG Name               data-vg
  PV Size               <50.00 GiB / not usable 0   
  Allocatable           yes 
  PE Size               4.00 MiB
  Total PE              12799
  Free PE               8000
  Allocated PE          4799
  PV UUID               xyz987-uvw6-5432-10zy-xwvu98765432

Display Specific Physical Volume

sudo pvdisplay /dev/sda2

Sample Output:

  --- Physical volume ---
  PV Name               /dev/sda2
  VG Name               ubuntu-vg
  PV Size               <19.00 GiB / not usable 0   
  Allocatable           yes (but full)
  PE Size               4.00 MiB
  Total PE              4863
  Free PE               0
  Allocated PE          4863
  PV UUID               abc123-def4-5678-90ab-cdef12345678

Advanced Usage Examples

Short Format Display

sudo pvdisplay -s

Sample Output:

  "/dev/sda2" is a new physical volume of "<19.00 GiB"
  "/dev/sdb1" is a new physical volume of "<50.00 GiB"

Colon-Separated Format

sudo pvdisplay -c

Sample Output:

  /dev/sda2:ubuntu-vg:19922944:-1:8:8:-1:4096:4863:3584:1279:abc123-def4-5678-90ab-cdef12345678
  /dev/sdb1:data-vg:52428800:-1:8:8:-1:4096:12799:4799:8000:xyz987-uvw6-5432-10zy-xwvu98765432

Display Physical Extent Maps

sudo pvdisplay -m /dev/sda2

Sample Output:

  --- Physical volume ---
  PV Name               /dev/sda2
  VG Name               ubuntu-vg
  PV Size               <19.00 GiB / not usable 0   
  Allocatable           yes (but full)
  PE Size               4.00 MiB
  Total PE              4863
  Free PE               0
  Allocated PE          4863
  PV UUID               abc123-def4-5678-90ab-cdef12345678
  
  --- Physical Segments ---
  Physical extent 0 to 2047:
    Logical volume      /dev/ubuntu-vg/ubuntu-lv
    Logical extent      0 to 2047
  Physical extent 2048 to 4862:
    Logical volume      /dev/ubuntu-vg/swap_1
    Logical extent      0 to 2814

Column Format Display

Basic Column Output

sudo pvdisplay -C

Sample Output:

  PV         VG        Fmt  Attr PSize  PFree 
  /dev/sda2  ubuntu-vg lvm2 a--  <19.00g    0 
  /dev/sdb1  data-vg   lvm2 a--  <50.00g <31.25g

Custom Column Selection

sudo pvdisplay -C -o pv_name,vg_name,pv_size,pv_free,pv_used

Sample Output:

  PV         VG        PSize  PFree  PUsed 
  /dev/sda2  ubuntu-vg <19.00g    0  <19.00g
  /dev/sdb1  data-vg   <50.00g <31.25g <18.75g

Understanding Output Fields

Key Information Fields

• PV Name: The device path of the physical volume
• VG Name: Volume group the PV belongs to
• PV Size: Total size of the physical volume
• Allocatable: Whether the PV can be used for allocation
• PE Size: Physical extent size (default 4MB)
• Total PE: Total number of physical extents
• Free PE: Number of unallocated physical extents
• Allocated PE: Number of allocated physical extents
• PV UUID: Unique identifier for the physical volume

Practical Use Cases

Monitoring Disk Usage

# Check available space on all PVs
sudo pvdisplay -C -o pv_name,pv_size,pv_free,pv_used --units g

Identifying Full Physical Volumes

# Find PVs with no free space
sudo pvdisplay -C | awk '$6 == 0 {print $1}'

Generating Reports

# Create a detailed report of all PVs
sudo pvdisplay -v > /tmp/pv_report.txt

Troubleshooting Common Issues

Permission Denied

Always run pvdisplay with sudo privileges:

sudo pvdisplay

No Physical Volumes Found

If no output appears, check if LVM is properly configured:

# Check if LVM tools are installed
which lvm

# Scan for physical volumes
sudo pvscan

Incomplete Information

Use verbose mode for detailed troubleshooting:

sudo pvdisplay -vv

Integration with Other LVM Commands

Combined Workflow

# Complete LVM status check
sudo pvdisplay -s        # Quick PV overview
sudo vgdisplay -s        # Volume group summary  
sudo lvdisplay -C        # Logical volume details

Scripting Integration

#!/bin/bash
# Simple PV monitoring script

echo "Physical Volume Status Report"
echo "============================="
sudo pvdisplay -C --units g
echo ""
echo "PVs with less than 10% free space:"
sudo pvdisplay -C --units g | awk 'NR>1 && $6/$5*100 < 10 {print $1, $6, $5}'

Best Practices

• Regular Monitoring: Use pvdisplay in monitoring scripts to track disk usage
• Document Configuration: Save PV layouts using pvdisplay > backup.txt
• Use Appropriate Format: Choose column format for scripting, detailed format for manual inspection
• Combine with Other Tools: Use alongside df, lsblk, and other storage commands
• Automate Reports: Create scheduled reports for capacity planning

Security Considerations

The pvdisplay command requires root privileges to access low-level disk information. Always:

• Use sudo instead of switching to root user
• Limit access to storage management commands
• Log administrative activities for audit trails
• Be cautious when sharing output as it may contain sensitive system information

Conclusion

The pvdisplay command is an invaluable tool for Linux system administrators managing LVM configurations. Whether you’re monitoring disk usage, troubleshooting storage issues, or planning capacity expansion, mastering this command will significantly enhance your storage management capabilities. Regular use of pvdisplay helps maintain healthy storage systems and prevents unexpected disk space shortages.

Remember to combine pvdisplay with other LVM commands like vgdisplay and lvdisplay for comprehensive storage management. Practice using different output formats and options to find the most efficient workflow for your specific administrative needs.