xfs_info Command Linux: Complete Guide to Display XFS Filesystem Information

The xfs_info command is a powerful utility in Linux systems that provides comprehensive information about XFS filesystems. This command is essential for system administrators who need to understand filesystem characteristics, troubleshoot issues, or optimize storage performance.

What is xfs_info Command?

The xfs_info command displays detailed metadata information about mounted XFS filesystems. It reveals crucial details such as block sizes, inode allocation policies, log configurations, and various filesystem parameters that affect performance and behavior.

XFS (eXtended File System) is a high-performance journaling filesystem originally developed by Silicon Graphics. It’s designed to handle large files and filesystems efficiently, making it popular in enterprise environments and high-performance computing scenarios.

Basic Syntax and Usage

The basic syntax of the xfs_info command is straightforward:

xfs_info [options] mountpoint|device

Parameters:

• mountpoint: The directory where the XFS filesystem is mounted
• device: The device file containing the XFS filesystem

Installation and Prerequisites

Before using xfs_info, ensure that XFS utilities are installed on your system:

Ubuntu/Debian:

sudo apt update
sudo apt install xfsprogs

CentOS/RHEL/Fedora:

sudo yum install xfsprogs
# or for newer versions
sudo dnf install xfsprogs

Basic Examples

Example 1: Display Information for Mounted Filesystem

Let’s examine a typical XFS filesystem mounted at /home:

xfs_info /home

Sample Output:

meta-data=/dev/sda2              isize=512    agcount=4, agsize=6553600 blks
         =                       sectsz=4096  attr=2, projid32bit=1
         =                       crc=1        finobt=1, sparse=1, rmapbt=0
         =                       reflink=1
data     =                       bsize=4096   blocks=26214400, imaxpct=25
         =                       sunit=0      swidth=0 blks
naming   =version 2              bsize=4096   ascii-ci=0, ftype=1
log      =internal               bsize=4096   blocks=12800, version=2
         =                       sectsz=4096  sunit=1 blks, lazy-count=1
realtime =none                   extsz=4096   blocks=0, rtextents=0

Example 2: Using Device Path

You can also specify the device directly:

xfs_info /dev/sda2

This produces the same output as the previous example, showing that both mountpoint and device specifications work identically.

Understanding xfs_info Output

The output from xfs_info is organized into several sections, each providing specific information about different aspects of the filesystem:

Meta-data Section

• isize=512: Inode size in bytes
• agcount=4: Number of allocation groups
• agsize=6553600 blks: Size of each allocation group in blocks
• sectsz=4096: Sector size in bytes
• attr=2: Extended attribute version
• projid32bit=1: 32-bit project ID support enabled
• crc=1: CRC checking enabled
• finobt=1: Free inode B-tree feature enabled
• sparse=1: Sparse inode support enabled
• reflink=1: Reference linking support enabled

Data Section

• bsize=4096: Block size in bytes
• blocks=26214400: Total number of data blocks
• imaxpct=25: Maximum percentage of space for inodes
• sunit=0, swidth=0: Stripe unit and stripe width (RAID optimization)

Naming Section

• version 2: Directory naming version
• bsize=4096: Directory block size
• ascii-ci=0: ASCII case-insensitive naming disabled
• ftype=1: File type information stored in directory entries

Log Section

• internal: Log is stored internally within the filesystem
• bsize=4096: Log block size
• blocks=12800: Number of log blocks
• version=2: Log format version
• lazy-count=1: Lazy superblock counter updates enabled

Realtime Section

• none: No realtime device configured
• extsz=4096: Realtime extent size
• blocks=0: Number of realtime blocks

Advanced Usage Examples

Example 3: Checking Multiple Filesystems

To check information for multiple XFS filesystems, you can use a simple loop:

for mount in /home /var /opt; do
    echo "=== Information for $mount ==="
    xfs_info $mount 2>/dev/null || echo "$mount is not an XFS filesystem"
    echo
done

Example 4: Extracting Specific Information

To extract only the block size information:

xfs_info /home | grep "data" | grep -o "bsize=[0-9]*"

Output:

bsize=4096

Example 5: Getting Filesystem Size

Calculate the total filesystem size:

xfs_info /home | awk '/data/ && /blocks=/ {
    match($0, /bsize=([0-9]+)/, bsize)
    match($0, /blocks=([0-9]+)/, blocks)
    size_bytes = bsize[1] * blocks[1]
    size_gb = size_bytes / 1024 / 1024 / 1024
    printf "Filesystem size: %.2f GB\n", size_gb
}'

Practical Use Cases

Performance Optimization

Understanding filesystem parameters helps optimize performance:

• Block size: Larger blocks can improve performance for large files
• Allocation groups: More groups can improve parallel I/O performance
• Stripe settings: Important for RAID configurations

Troubleshooting

Use xfs_info to diagnose issues:

# Check if filesystem has modern features
xfs_info /data | grep -E "(crc|finobt|reflink)"

# Verify log configuration
xfs_info /data | grep "log"

Migration Planning

Before migrating data, understand source filesystem characteristics:

# Create a summary script
#!/bin/bash
MOUNT_POINT=$1
echo "XFS Filesystem Summary for $MOUNT_POINT"
echo "======================================"
INFO=$(xfs_info $MOUNT_POINT)
echo "Block Size: $(echo "$INFO" | grep -o 'bsize=[0-9]*' | head -1 | cut -d= -f2) bytes"
echo "Inode Size: $(echo "$INFO" | grep -o 'isize=[0-9]*' | cut -d= -f2) bytes"
echo "Allocation Groups: $(echo "$INFO" | grep -o 'agcount=[0-9]*' | cut -d= -f2)"
echo "CRC Enabled: $(echo "$INFO" | grep -o 'crc=[0-1]' | cut -d= -f2)"

Error Handling and Common Issues

Common Error Messages

Error: “xfs_info: /path is not a mounted XFS filesystem”

This occurs when:

• The path is not mounted
• The filesystem is not XFS
• You don’t have sufficient permissions

Solution:

# Check if path is mounted and filesystem type
mount | grep /path
df -T /path

Permission Issues

If you encounter permission errors, ensure you have read access to the mount point:

ls -ld /mount/point
# If needed, run with sudo
sudo xfs_info /mount/point

Comparison with Other Filesystem Tools

Best Practices

Regular Monitoring

Create monitoring scripts to track filesystem parameters:

#!/bin/bash
# xfs_monitor.sh
LOG_FILE="/var/log/xfs_info.log"
date >> $LOG_FILE
for fs in $(mount | grep xfs | awk '{print $3}'); do
    echo "=== $fs ===" >> $LOG_FILE
    xfs_info $fs >> $LOG_FILE 2>&1
done

Documentation

Always document your filesystem configurations:

# Generate documentation
xfs_info /data > /docs/xfs_data_config.txt

Integration with System Administration

Automated Reporting

Integrate xfs_info into system monitoring:

# Check for filesystem features
if xfs_info /data | grep -q "reflink=1"; then
    echo "Reflink feature available for deduplication"
fi

Backup Verification

Verify filesystem parameters match between source and backup systems:

# Compare filesystem configurations
diff <(xfs_info /source | sort) <(xfs_info /backup | sort)

Conclusion

The xfs_info command is an indispensable tool for managing XFS filesystems in Linux environments. It provides comprehensive information about filesystem structure, features, and configuration that is crucial for system administration, performance optimization, and troubleshooting.

Key takeaways:

• Use xfs_info to understand filesystem characteristics before making changes
• Regular monitoring helps identify potential issues early
• Understanding the output helps optimize performance for specific workloads
• Combine with other tools for comprehensive filesystem management

By mastering xfs_info, system administrators can make informed decisions about storage management, ensure optimal performance, and maintain reliable XFS filesystems in production environments.