Archiving and compressing files

Parent page: Storage and file management

Archiving means creating one file that contains a number of smaller files within it. Reducing the number of files by creating an archive can improve the efficiency of file storage and help you stay within quota limits. Archiving can also improve the efficiency of file transfers. It is faster for the secure copy protocol (scp), for example, to transfer one archive file of a reasonable size than thousands of small files of equal total size.

Compressing means encoding a file such that the same information is contained in fewer bytes of storage. The advantage for long-term data storage should be obvious. For data transfers, the time spent for compressing data must be balanced against the time saved moving fewer bytes as described in this discussion of data compression and transfer from the US National Center for Supercomputing Applications.

• The best-known tool for archiving files in the Linux community is tar. Here is a tutorial on 'tar'.
• A replacement for tar called dar offers some advantages in functionality. Here is a tutorial on 'dar'. Both tar and dar can compress files as well as archive.
• The zip utility, more commonly used in the Windows community but available on our clusters, also provides both archiving and compression.
• Compression tools gzip, bzip2 and xz can be used in conjunction with tar, or by themselves.