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How to Speed Up Copy in Linux?

Published in File Management 4 mins read

There are several ways to speed up file copying in Linux, depending on the specific situation and the tools you have available. Here's a breakdown of common approaches:

1. Using cp with Optimized Options

The basic cp command can be surprisingly efficient with the right options.

  • -R or -r (Recursive): Use this to copy directories and their contents. It handles subdirectories and files within them.

  • -a (Archive): This is often the best general-purpose option. It preserves file attributes like permissions, ownership, timestamps, and symbolic links. It's essentially equivalent to -dR --preserve=all.

Example:

cp -a /path/to/SOURCE_FOLDER/ /path/to/DESTINATION_FOLDER/
  • Why it works: -a ensures that metadata is preserved, which can be crucial for certain applications and avoids potentially time-consuming recalculations.

Important Note: If you are copying within the same filesystem, hard links might be created instead of actual copies, which will be faster but means changes to one file affect the other.

2. Leveraging rsync for Efficient Transfers

rsync is a powerful utility designed for synchronizing files and directories. It's particularly good at incremental backups and transfers, as it only copies the differences between the source and destination.

  • -a (Archive): Same as with cp, preserves file attributes.
  • -v (Verbose): Increases the output to show which files are being transferred.
  • -z (Compress): Compresses the data during transfer, which can be helpful when copying over a network.
  • --progress: Displays a progress bar, which is useful for large transfers.

Example:

rsync -av /path/to/SOURCE_FOLDER/ /path/to/DESTINATION_FOLDER/

Why it's faster: rsync avoids copying files that are already identical in the destination. This is a huge time-saver when you're updating a directory or making backups.

3. Utilizing tar for Archiving and Copying

tar (Tape Archive) can be used to create an archive and then extract it in the destination, sometimes providing a performance benefit due to more efficient disk I/O. This method can be faster, especially when dealing with a large number of small files.

Steps:

  1. Create the archive:

    tar -cf - /path/to/SOURCE_FOLDER | (cd /path/to/DESTINATION_FOLDER && tar -xf -)
    • -c: create
    • -f -: Use standard output for the archive

  2. Extract the archive: The second part of the command pipes the output of tar into another tar command that extracts the archive.

    • cd /path/to/DESTINATION_FOLDER: Changes the directory to the destination.
    • -x: extract
    • -f -: Read from standard input

Why it can be faster: tar reads and writes data in larger chunks, reducing the overhead of individual file operations. The pipe also enables parallel read and write operations.

4. Other Considerations

  • Disk Speed: The speed of your hard drives (or SSDs) is a primary factor. Faster drives will significantly improve copy speeds.

  • Filesystem Type: Different filesystems have different performance characteristics. Some filesystems might be optimized for certain workloads.

  • System Load: High system load (CPU, memory, I/O) can slow down copy operations. Close unnecessary programs during the copy process.

  • Network Speed (for network copies): The speed of your network connection is crucial when copying files over a network. Use scp or rsync with compression (-z) for improved network efficiency.

  • ionice (I/O Scheduling): Use ionice to prioritize the cp, rsync, or tar command to get more I/O resources.

    ionice -c 1 cp -a /path/to/SOURCE_FOLDER/ /path/to/DESTINATION_FOLDER/
    • -c 1: Sets the I/O scheduling class to "realtime". Use with caution as it can impact other processes. -c 2 ("best-effort") is often a safer choice.

Summary

To speed up file copying in Linux, choose the right tool for the job. For simple copies, cp -a is a good starting point. rsync excels at incremental backups and network transfers. tar can improve performance when dealing with a large number of small files. Always consider your hardware limitations and overall system load.

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