flags on backuped mails

[Phil Pennock]

On 2006-11-14 at 13:18 +0100, Marten Lehmann wrote:
> 2. Why aren't flags stored in the file name, too? I used to see that 
> with Maildirs and it is very clever: Flags are permanent and aren't lost 
> if the index is broken. Anyway, the index speeds up access to the flags 
> and the index can be rebuild from the flags in the filename. The 
> flag-structure might be adopted from the Maildir-specification.

(1) That doesn't allow for per-user flags, only global flags.  Shared
    folders.

(2) With large-scale servers, this means that every flag-based action
    involves a rename, which means file-system internal locks on the
    directory.  This doesn't scale at the high end, but isn't a problem
    for small to mid-size installations.  File renames are not free and
    they push the atomicity where you really don't want to be pushing it
    for scalability, although it can be simple.

-Phil, not running high-end Cyrus, but has run a largish mail-system in
       previous employment.