On 2019-02-22, David Pottage via dovecot dovecot@dovecot.org wrote:
On 2019-02-21 22:14, Christoph Haas via dovecot wrote:
NO! My mail storage is mdbox. And at the moment I have no intention to convert it to Maildir! Could I ask why? maildir is a better storage format is almost every respect.
well, I have a mailbox with about 50k emails ..., so one reason seems to me better backup performance with mdbox, since there are much less files to save.
Assuming that you backup regularly then maildir is much better, because new emails show up as new files, while old ones are left unchanged. This means that an incremental backup only has to process new emails. With mailbox, the file for the entire folder changes every time a new email is delivered or the user edits any of them, so the whole mailbox needs to be backed up again, resulting in far more I/O and time.
It sounds like perhaps you're confusing mdbox with mbox. mdbox uses multiple files but not a single file per message. It is fairly sane for backup handling - depending on how you set things up, you can have it rotate after a fixed size, fixed time, or combination.