PHP disk_total_space Function

last modified April 3, 2025

The PHP disk_total_space function returns the total size of a filesystem or disk partition. It’s useful for storage monitoring and management.

Basic Definition

The disk_total_space function returns the total space in bytes for the filesystem that the specified directory is on. It takes one parameter.

Syntax: disk_total_space(string $directory): float|false. Returns total bytes as float or false on failure. Requires filesystem permissions.

Basic disk_total_space Example

This shows the simplest usage of disk_total_space to get disk size.

basic_disk_space.php

<?php

declare(strict_types=1);

$directory = “/”; $totalSpace = disk_total_space($directory);

echo “Total space: " . $totalSpace . " bytes”;

This returns the total space of the root filesystem in bytes. The function requires read permissions for the specified directory path.

Converting Bytes to Human-Readable Format

Disk space is often more readable when converted to larger units.

human_readable.php

<?php

declare(strict_types=1);

function formatBytes(float $bytes, int $precision = 2): string { $units = [‘B’, ‘KB’, ‘MB’, ‘GB’, ‘TB’]; $bytes = max($bytes, 0); $pow = floor(($bytes ? log($bytes) : 0) / log(1024)); $pow = min($pow, count($units) - 1); $bytes /= (1 << (10 * $pow)); return round($bytes, $precision) . ’ ’ . $units[$pow]; }

$space = disk_total_space("/"); echo “Total space: " . formatBytes($space);

This converts raw bytes to a human-readable format like GB or TB. The helper function handles the conversion with configurable precision.

Checking Multiple Disks

You can check space on multiple mounted filesystems with one script.

multiple_disks.php

<?php

declare(strict_types=1);

$disks = [ “/” => “Root”, “/home” => “Home”, “/mnt/data” => “Data Storage” ];

foreach ($disks as $path => $name) { $space = disk_total_space($path); if ($space !== false) { echo “$name: $space bytes\n”; } else { echo “Failed to read $name disk\n”; } }

This checks multiple mounted filesystems and handles potential failures. Each disk is labeled for clarity in the output.

Calculating Free Space Percentage

Combine with disk_free_space to calculate usage percentages.

free_space_percent.php

<?php

declare(strict_types=1);

$directory = “/”; $total = disk_total_space($directory); $free = disk_free_space($directory);

if ($total !== false && $free !== false) { $used = $total - $free; $percentUsed = ($used / $total) * 100; echo “Disk usage: " . round($percentUsed, 2) . “%”; } else { echo “Unable to determine disk usage”; }

This calculates the percentage of disk space used. Both functions must succeed for the calculation to work. Error handling is included.

Windows Drive Example

The function works with Windows drive letters when properly formatted.

windows_drive.php

<?php

declare(strict_types=1);

$drive = “C:\”; $space = disk_total_space($drive);

if ($space !== false) { echo “Drive C: total space: " . $space . " bytes”; } else { echo “Unable to read drive C:”; }

On Windows, use backslashes and include the trailing slash. The function returns the total capacity of the specified drive in bytes.

Edge Cases

disk_total_space has specific behaviors with certain inputs.

edge_cases.php

<?php

declare(strict_types=1);

// Non-existent path $result1 = disk_total_space("/nonexistent/path”);

// No permissions $result2 = disk_total_space("/root”);

var_dump($result1); // bool(false) var_dump($result2); // bool(false) if no permissions

The function returns false for invalid paths or when permissions are insufficient. Always check the return value before using the result in calculations.

Best Practices

• Error Handling: Always check for false return values.

• Permissions: Ensure script has filesystem read access.

• Network Paths: May not work reliably with network shares.

• Caching: Results may be cached by the OS between calls.

• Units: Convert bytes for human-readable displays.

Source

PHP disk_total_space Documentation

This tutorial covered the PHP disk_total_space function with practical examples showing disk space monitoring in different scenarios.

Author

My name is Jan Bodnar, and I am a passionate programmer with extensive programming experience. I have been writing programming articles since 2007. To date, I have authored over 1,400 articles and 8 e-books. I possess more than ten years of experience in teaching programming.

List all PHP Filesystem functions.