1 reply to this topic

[Jeremy Trask]

Hi Steve

Thanks for your interest in BackupBuddy.

The tar archive file format is not supported - please note that the tar file format is _only_ an archive format and does _not_ in itself support compression within the archive. Compressing a tar archive file is a separate operation that must be applied to the whole tar archive and this makes certain operations upon such a compressed archive less efficient and more processor intensive. The tar format is very dated (it originated in the days of tape backup) and has a number of weaknesses such that it may be suitable for basic complete system backups that a host might make but isn't really suitable for the type of use that users looking at something like BackupBuddy will be interested in. A host support that suggests using tar instead of zip either doesn't really understand the difference or has some other motivation for making such a suggestion.

The zip archive format supports per-file compression directly meaning that each file can be compressed as it is added to the archive which among other things allows decisions to be made about whether it is worth trying to compress a file (some files are already in a compressed format - some image files for example - and blindly trying to compress such a file is inefficient and wasteful if processor) and also allows direct access to individual files without having to decompress the complete archive. It is true that the ultimate size of a zip archive may be slightly more than that of an equivalent compressed tar archive but generally the difference is insignificant and outweighed by the other advantages of using the zip archive format.

As far as BackupBuddy is concerned it supports the use of the zip archive format through different means depending on what the hosting makes available. It will use command line zip/unzip utilities if these are available as this is the most efficient way to go but if the host does not make these available then it will fall back to using what we call a Compatibility Mode which uses a PHP library (that is included as a standard component in WordPress because WordPress needs to handle zip files) and standard underlying operating system libraries used by this in order to handle zip archive files (including compression). Because this is based more on PHP scripting rather than operating system command line utilities it will generally be slower but produces exactly the same zip archive files (sometimes slightly smaller if the operating system compression libraries are more efficient than those used by the zip utility).

I hope this provides the information that you need, if you have any further question or clarification required in this respect please let us know, thanks.

Regards...jeremy