In order to save space I prefer no to have such half-files (mails) , and it is for this reason that I am asking if there is any way to prevent this.

I'm not an expert in field of file systems, so I can be asking very naive questions... but I appreciate your comments on this topic.

Filesystem consistency is different than, for lack of a better term, dovecot consistency. The latter places additional constraints on the content of files, rather than treating them as sequences of disk blocks.

I don't think you can ensure the latter without stopping all dovecot processes (and maybe the MTA/LDA as well), which will be much more difficult and disruptive than just taking a snapshot.

(I think some snapshot aware application like databases and hypervisors allows the operator to put the application in a state of acquiesence, long enough to take a snapshot, then unblock all processes after the snapshot.)

I'd take the suggestion of the previous poster: take snapshots, don't worry, be happy. The small amount of inconsistencies is trivial compared with quickly recovering a mail store after disaster.

Joseph Tam <jtam.home@gmail.com>