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RAM Disk Utility - (ramdisk.py)

Python Version License: MIT Platform: Linux Made with: Shell commands

ramdisk.py is a Python script designed to simplify the creation and removal of RAM disks on Linux systems. It supports both traditional tmpfs RAM disks and compressed ZRAM RAM disks, providing a command-line interface to manage a RAM disk located at /ramdisk.

Features

  • Dual RAM Disk Types:
    • tmpfs RAM Disk: Create a standard RAM disk stored in volatile system memory.
    • ZRAM RAM Disk: Create a compressed RAM disk using ZRAM, potentially saving memory while still offering RAM-like speeds.
  • User-Specified Size: Easily create a RAM disk with a defined size (e.g., "4G" for 4 Gigabytes, "512M" for 512 Megabytes, "100K" for 100 Kilobytes).
  • Simple Removal: Cleanly unmounts and removes the RAM disk, automatically detecting if it's tmpfs or ZRAM for appropriate cleanup.
  • Fixed Mount Point: Operates on a predefined mount point: /ramdisk.
  • Directory Management: Automatically creates the /ramdisk directory if it doesn't exist during creation and removes it during the removal process.
  • Sudo Requirement: Enforces execution with sudo privileges, as mounting and unmounting filesystems are restricted operations.
  • Prerequisite Checks: For ZRAM, checks for necessary utilities like zramctl and mkfs.ext2.
  • Input Validation: Includes basic validation for the size argument format.
  • Status Messages: Provides informative messages about its operations and any errors encountered.

Script Workflow

The script operates based on the command-line arguments provided.

RAM Disk Creation

  1. Sudo Check: Verifies if the script is run with sudo privileges. Exits if not.
  2. Argument Parsing: Determines if a tmpfs or ZRAM disk is requested (via the optional --zram flag) and validates the size argument.
  3. Mount Point Check: Ensures /ramdisk is not already a mount point.
  4. Directory Creation: If /ramdisk does not exist, it's created.

tmpfs Creation (sudo python3 ramdisk.py <size>)

  1. Mount tmpfs: Executes mount -t tmpfs -o size=<size_str> tmpfs /ramdisk.

ZRAM Creation (sudo python3 ramdisk.py <size> --zram)

  1. Prerequisite Check: Verifies zramctl and mkfs.ext2 (or the configured ZRAM_FS_TYPE tool) are available.
  2. Load ZRAM Module: Ensures the zram kernel module is loaded using modprobe zram.
  3. Configure ZRAM Device:
    • Uses zramctl --find --size <size_str> --algorithm <ZRAM_COMP_ALGORITHM> to find an available ZRAM device (e.g., /dev/zram0), set its disk size, and specify the compression algorithm (default: lz4).
  4. Format ZRAM Device: Formats the allocated ZRAM device with the specified filesystem (default: ext2) using mkfs.<ZRAM_FS_TYPE> /dev/zramX.
  5. Mount ZRAM Device: Mounts the formatted ZRAM device to /ramdisk.

RAM Disk Removal (sudo python3 ramdisk.py remove)

  1. Sudo Check: Verifies sudo privileges.
  2. Mount Information Retrieval: If /ramdisk is mounted, uses findmnt (with a fallback to parsing /proc/mounts) to determine the source device and filesystem type.
  3. Unmount Operation: Unmounts /ramdisk using umount /ramdisk.
  4. ZRAM Device Reset (if applicable): If the source device was a ZRAM device (e.g., /dev/zramX), it resets the device using zramctl --reset /dev/zramX. This frees up the ZRAM device.
  5. Directory Removal: Attempts to remove the /ramdisk directory if it exists and is empty.

Installation

  1. Save the Script: Save the Python code into a file named ramdisk.py.

  2. Make it Executable (Optional but Recommended): Open your terminal and run:

    chmod +x ramdisk.py

  3. Dependencies:

    • Python 3.x
    • Standard Linux command-line utilities (mount, umount, mkdir, modprobe).
    • For tmpfs (usually pre-installed): No special dependencies beyond standard utilities.
    • For ZRAM:
      • util-linux: Provides the zramctl utility.
        • Debian/Ubuntu: sudo apt install util-linux
        • Fedora: sudo dnf install util-linux
      • e2fsprogs (or tools for your chosen ZRAM_FS_TYPE): Provides mkfs.ext2.
        • Debian/Ubuntu: sudo apt install e2fsprogs
        • Fedora: sudo dnf install e2fsprogs
      • The zram kernel module must be available and loadable.

Usage Examples

Note: All commands must be run with sudo.

  1. Create a 4GB tmpfs RAM Disk:

    sudo python3 ramdisk.py 4G

    If executable: sudo ./ramdisk.py 4G

  2. Create a 1GB ZRAM RAM Disk (compressed):

    sudo python3 ramdisk.py 1G --zram

    If executable: sudo ./ramdisk.py 1G --zram

  3. Create a 512MB tmpfs RAM Disk:

    sudo python3 ramdisk.py 512M

  4. Verify RAM Disk Creation:

    • For both types: 
      df -h /ramdisk
mount | grep /ramdisk
    • Additionally for ZRAM: 
      zramctl
# Check /proc/swaps if you configured it as swap, though this script uses it as a block device for a filesystem

  5. Remove the RAM Disk (works for both tmpfs and ZRAM):

    sudo python3 ramdisk.py remove

    If executable: sudo ./ramdisk.py remove

Important Considerations

  • Sudo Privileges: Essential for all operations.
  • Linux Specific: Relies on Linux-specific tools and kernel features (tmpfs, zram, mount, zramctl).
  • Data Volatility:
    • tmpfs: Data is stored in RAM and is lost on unmount or reboot.
    • ZRAM: Data is stored in a compressed form in RAM. It is also lost on unmount (which includes ZRAM device reset) or reboot.
  • Mount Point: Uses the hardcoded /ramdisk mount point.
  • ZRAM Specifics:
    • Compression: ZRAM uses compression (default lz4 in the script). The actual memory used will be less than the specified disk size, depending on data compressibility.
    • Performance: ZRAM involves a CPU overhead for compression/decompression. For highly compressible data, it can effectively increase available RAM for the disk. lz4 is generally fast.
    • Kernel Module: The zram kernel module must be available.
    • Filesystem on ZRAM: The script formats the ZRAM device with ext2 by default. This is a lightweight filesystem suitable for temporary use.
  • Error Handling: The script provides basic error messages. If umount fails due to "target is busy," use lsof /ramdisk or fuser -vm /ramdisk to find and stop processes using the RAM disk.

License

This script is released under the MIT License.

MIT License

Copyright (c) 2025 Cameron Walker - me@cameronwalker.nz

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.