Maybe I misunderstand.  Each user is only able to access their mailbox from a single connection at a time.  Other users can access the NFS Spool from other connections, I think that is what I am calling Concurrent connections.

Is that the same definition you have?

From: dovecot [mailto:dovecot-bounces@dovecot.org] On Behalf Of Aki Tuomi
Sent: Friday, October 19, 2018 10:05 AM
To: Albert Whale <Albert.Whale@it-security-inc.com>; dovecot@dovecot.org
Subject: RE: Dovecot 2.2.13 error message

Concurrent access is not supported. One user should access mail using one backend at a time. You can use dovecot in director mode to prevent this.

Aki

On 19 October 2018 at 16:47 Albert Whale < Albert.Whale@IT-Security-inc.com> wrote:

Yes, there is currently concurrent usage because the Mail spool is NFS

Mounted.

Here is the current configuration:

dovecot -n

# 2.1.15: /etc/dovecot/dovecot.conf

# OS: Linux 3.10.54-server-2.mga3 i686 Mageia 3

base_dir = /var/run/dovecot/

disable_plaintext_auth = no

lock_method = dotlock

login_greeting = SpamZapper Email ready.

login_log_format_elements = user=<%u> method=%m rip=%r lip=%l %c

mail_debug = yes

mail_fsync = always

mail_location = maildir:~/Maildir

mail_nfs_index = yes

mail_nfs_storage = yes

mail_privileged_group = mail

mbox_lock_timeout = 15 mins

mmap_disable = yes

passdb {

driver = pam

}

protocols = imap pop3

service anvil {

client_limit = 1000

process_limit = 1

}

service auth {

user = root

}

service imap-login {

chroot = login

client_limit = 10

user = dovecot

vsz_limit = 256 M

}

service pop3-login {

chroot = login

client_limit = 1024

user = dovecot

}

ssl = no

syslog_facility = local2

userdb {

driver = passwd

}

verbose_proctitle = yes

protocol pop3 {

mail_max_userip_connections = 20

pop3_logout_format = top=%t/%p, retr=%r/%b, del=%d/%m, size=%s

pop3_uidl_format = %08Xv%08Xu

}

protocol lda {

postmaster_address = postmaster@example.com

}

protocol imap {

mail_max_userip_connections = 30

}

For the time being, I have isolated usage of POP3 connections on a single

Servers, however IMAP is especially problematic.

From: Aki Tuomi [mailto: aki.tuomi@open-xchange.com]

Sent: Friday, October 19, 2018 2:51 AM

To: Albert Whale < Albert.Whale@IT-Security-inc.com>; dovecot@dovecot.org

Subject: Re: Dovecot 2.2.13 error message

On 18.10.2018 15.15, Albert Whale wrote:

In attempting to reactivate my IMAP communications with my Email Spool (NFS

Mounted), I have gotten the following while attempting to download the

Emails via POP3.

Oct 18 08:00:45 ns4 dovecot: pop3-login: Login: user=<aewhale>,

method=PLAIN, rip=74.109.213.194, lip=66.207.133.232

Oct 18 08:02:40 ns4 dovecot: pop3(aewhale): Error: Timeout (180s) while

waiting for dotlock for transaction log file

/home/aewhale/Maildir/dovecot.index.log

Oct 18 08:02:40 ns4 dovecot: pop3(aewhale): Disconnected: Storage error

during logout. top=0/0, retr=11511/1566975544, del=11511/11511,

size=1566691807

Oct 18 08:02:58 ns4 dovecot: pop3(aewhale): Connection closed top=0/0,

retr=0/0, del=0/11520, size=1566929900

This is significantly more information than what I can receive from 2.1.15,

but still does not resolve the communications issues.

Any help is certainly appreciated.

--

Albert E. Whale, CEH CHS CISA CISSP

Hi!

Seems something is locking the index. Do you have concurrent usage between

two or more nodes for same user?

Aki

---
Aki Tuomi