Thanks Aki.  For the number of users I have I'm sure the NFS is fast enough, but I've implemented in shared memory already and it seems to be working fine. I appreciate the confirmation that it is OK to make changes to the prestart script.

Doug

On 4/10/2022 2:28 PM, Aki Tuomi wrote:
Hi!

Dovecot uses permissions from mail user storage folder and in absence of that, 
the parent folder.

Your pre-start script looks good.

If your NFS is fast enough, it's ok to keep .cache and .log in NFS.

Aki

On 25/03/2022 18:57 João Silva<joaopfml...@lipc.fis.uc.pt>  wrote:


In that case things can be more peacefull.
I once had the mail in a NFS storage and was told to move to local storage 
because of speed issues.
Really don't know if the .cache and .log should be put in a fast local storage 
to speed up things.

On 25/03/2022 16:40, doug wrote:

Thank youJoão! I too am concerned if this is a risky configuration. My 
understanding is that the list indexes are not critical and that is why the 
recommendation in an NFS environment is to place just those and the lock files 
in memory. Other index files are on permanent storage:
[doug@mailserverdev doug]$ find ./ -name *index*
  ./mail/mailboxes/INBOX/dbox-Mails/dovecot.index.cache
  ./mail/mailboxes/INBOX/dbox-Mails/dovecot.index.log
  ./mail/storage/dovecot.map.index.log.2
  ./mail/storage/dovecot.map.index
  ./mail/storage/dovecot.map.index.log
Should I still be concerned? Doug


On 3/25/2022 11:46 AM, João Silva wrote:

I'm not sure about that configuration.

I have seen huge index cache files for users with lots of mail, putting those 
in memory may be a risk.


On 25/03/2022 14:56, doug wrote:

Hi,

  Environment: Dovecot 2.3.18 running on CentOS 7, mdbox, LDAP users
I'm in the process of moving my mailboxes to NFS and moving with lock and index files in temp storage following instructions fromhttps://doc.dovecot.org/configuration_manual/nfs. I set mail_location as:

mail_location = 
mdbox:/mailstore/%u/mail:VOLATILEDIR=/dev/shm/dovecot/%u:LISTINDEX=/dev/shm/dovecot/%u/dovecot.list.index

What I discovered is /dev/shm/dovecot is created by the initial user who 
accesses their mail from a client, and with permissions 700. This prevents 
subsequent users from creating their own index and lock files.

# ls -l /dev/shm/dovecot
total 0
drwx------ 2 mary users 60 Mar 25 10:00 mary


Sample error message from maillog during mail delivery and from a dsync script.
Mar 25 10:37:15 mailsrv1 dovecot: imap(doug)<19284><WKcX5gvbRe7AqFhA>: Error: 
mkdir(/dev/shm/dovecot/doug) failed: Permission denied (euid=1002(doug) egid=100(users) 
missing +x perm: /dev/shm/dovecot, dir owned by 97:100 mode=0700)

dsync(test): Error: mkdir(/dev/shm/dovecot/test) failed: Permission denied 
(euid=2003(test) egid=100(users) missing +x perm: /dev/shm/dovecot, dir owned 
by 97:100 mode=0700)


I couldn't locate documentation or discussions on how to set the ownership or 
permissions for /dev/shm/dovecot in the Dovecot configuration files.
As a hack, I added this to /usr/libexec/dovecot/prestartscript.

! [[ -d /dev/shm/dovecot ]] && mkdir /dev/shm/dovecot
  chown dovecot:users /dev/shm/dovecot
  chmod 770 /dev/shm/dovecot
This solved the problem, but left me wondering if I missed something obvious or 
if I am setting myself up for a problem later on, like with a Dovecot version 
upgrade.I could run these commands at bootup out of rc.local or a systemd 
script rather than customizing a Dovecot provided script.
Is there a appropriate way of doing this that I missed?

  TIA,
  Doug


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