Mailbox hierarchy determination?

[Simon Matter]

> The first couple of times I set up cyrus-imapd I used Debian packages
> which separated mailboxes in the default partition into folders based on
> the starting letter of the mailbox; i.e. something like:
>
>    /var/spool/cyrus/mail/{[A-Z,a-z,0-9]}/user
>
> Since I have fewer than 50 users and since I found myself frequently
> "going to the files" so to speak to definitely determine the presence or
> absence of some message a user was concerned about, this hierarchy was
> something of a annoyance, so during the last major upgrade I switched
> this to:
>
>     /srv/imap/{user1,user2,...,userN}
>
> i.e. flattening the folder structure and moving the default partition to
> a large non-system disk unaffected by /var volatility.
>
> Now for the life of me I can't figure out what setting in imapd.conf (if
> any) facilitated this structure (not the location of the default
> partition, but rather not using the [A-Z,a-z,0-9] subfolders.
>
> Last time I left the sieve folders divided by letter; in the next
> iteration I'd like to flatten that folder structure to.
>
> Looking at the Arch package post_install script, it pre-creates a ton of
> folders:
>
> --------------------------
>      # all kinds of directories needed for the IMAP spool
>      for subdir in imap/{,db,log,msg,proc,socket,sieve}
> spool/imap/{,stage.}; do
>          if [ ! -d /var/${subdir} ]; then
>              mkdir -m 0750 -p "/var/${subdir}"
>          fi
>      done
>      for subdir in imap/{user,quota,sieve} spool/imap; do
>          for i in a b c d e f g h i j k l m n o p q r s t v u w x y z \
>                   A B C D E F G H I J K L M N O P Q R S T U V W X Y Z \
>                   0 1 2 3 4 5 6 7 8 9; do
>              if [ ! -d /var/${subdir}/${i} ]; then
>                  mkdir -m 0750 -p "/var/${subdir}/${i}"
>              fi
>          done
> --------------------------
>
> I'm wondering how much or if any of this is really necessary. Will cyrus
> autocreate the necessary folders if missing?

Dirhashing is controlled by "fulldirhash" and "hashimapspool".

IIRC creating the dirs like above is not needed, they are created on demand.

Regards,
Simon