[Dovecot] Uncompressing dboxes

Timo Sirainen tss at iki.fi
Wed Feb 1 22:11:40 EET 2012

On 1.2.2012, at 17.43, Lauri Alanko wrote:

> I have an mdbox directory that has been created with the zlib plugin active, using bzip2 compression. I would now like to convert these into uncompressed mdbox format. How do I do this? I have tried unsetting all zlib-related configuration options, but dsync still produces compressed mdbox at the other end, too.

Do something like:

dsync backup dsync -o plugin/zlib_save= -o mail=mdbox:/tmp/uncompressed

> (Incidentally, it's a bit funny that when the zlib plugin is enabled, dsync automatically creates compressed dboxes, and even compressed maildirs (which is pretty useless), but not compressed mboxes, although that's where compression would be most beneficial.)

Dovecot supports only read-only compressed mboxes. Also compressed mboxes are always pretty slow, since there's no way to quickly jump around in the file (to go to offset X, you need to uncompress the first X bytes of the mbox file, that's one reason why for mdbox I decided against using full file compression).

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