I mean same user having concurrent session on more than one backend. This will likely cause index corruption. Same applies for dovecot doing delivery on differenr backend than where the user is currently logged in. 

Aki
On 19 October 2018 at 17:57 Albert Whale < Albert.Whale@IT-Security-inc.com> wrote:


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 <mailto: 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 <mailto: 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 <mailto: aki.tuomi@open-xchange.com> ]

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

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



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Aki Tuomi

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Aki Tuomi