no full syncs after upgrading to dovecot 2.3.18

Paul Kudla (SCOM.CA Internet Services Inc.) paul at
Sun Apr 24 17:36:16 UTC 2022

Question having similiar replication issues

pls read everything below and advise the folder counts on the 
non-replicated users?

i find  the total number of folders / account seems to be a factor and 
NOT the size of the mail box

ie i have customers with 40G of emails no problem over 40 or so folders 
and it works ok

300+ folders seems to be the issue

i have been going through the replication code

no errors being logged

i am assuming that the replication --> dhclient --> other server is 
timing out or not reading the folder lists correctly (ie dies after X 
folders read)

thus i am going through the code patching for log entries etc to find 
the issues.


[13:33:57] [root:0] /usr/local/var/lib/dovecot
# ll
total 86
drwxr-xr-x  2 root  wheel  uarch    4B Apr 24 11:11 .
drwxr-xr-x  4 root  wheel  uarch    4B Mar  8  2021 ..
-rw-r--r--  1 root  wheel  uarch   73B Apr 24 11:11 instances
-rw-r--r--  1 root  wheel  uarch  160K Apr 24 13:33 replicator.db

[13:33:58] [root:0] /usr/local/var/lib/dovecot

replicator.db seems to get updated ok but never processed properly.

# sync.users
nick at                   high     00:09:41  463:47:01 - 
keith at                  high     00:09:23  463:45:43 - 
paul at                      high     00:09:41  463:46:51 - 
ed at                        high     00:09:43  463:47:01 - 
ed.hanna at              high     00:09:42  463:46:58 - 
paul at                high     00:09:44  463:47:03 580:35:07 

so ....

two things :

first to get the production stuff to work i had to write a script that 
whould find the bad sync's and the force a dsync between the servers

i run this every five minutes or each server.

in crontab

*/10    *                *    *    *    root            /usr/bin/nohup 
/programs/common/sync.recover > /dev/null

python script to sort things out

# cat /programs/common/sync.recover

#Force sync between servers that are reporting bad?

import os,sys,django,socket
from optparse import OptionParser

from lib import *

#Sample Re-Index MB
#doveadm -D force-resync -u paul at -f INBOX*

usage: %%prog %s[options]

parser = OptionParser(usage=USAGE_TEXT % '', version='0.4')

parser.add_option("-m", "--send_to", dest="send_to", help="Send Email To")
parser.add_option("-e", "--email", dest="email_box", help="Box to Index")
parser.add_option("-d", "--detail",action='store_true', 
dest="detail",default =False, help="Detailed report")
parser.add_option("-i", "--index",action='store_true', 
dest="index",default =False, help="Index")

options, args = parser.parse_args()

print (options.email_box)
print (options.send_to)
print (options.detail)


print ('Getting Current User Sync Status')
command = commands("/usr/local/bin/doveadm replicator status '*'")

#print command

sync_user_status = command.output.split('\n')

#print sync_user_status

synced = []

for n in range(1,len(sync_user_status)) :
         user = sync_user_status[n]
         print ('Processing User : %s' %user.split(' ')[0])
         if user.split(' ')[0] != options.email_box :
                 if options.email_box != None :

         if options.index == True :
                 command = '/usr/local/bin/doveadm -D force-resync -u %s 
-f INBOX*' %user.split(' ')[0]
                 command = commands(command)
                 command = command.output

         #print user
         for nn in range (len(user)-1,0,-1) :
                 #print nn
                 #print user[nn]

                 if user[nn] == '-' :
                         #print 'skipping ... %s' %user.split(' ')[0]


                 if user[nn] == 'y': #Found a Bad Mailbox
                         print ('syncing ... %s' %user.split(' ')[0])

                         if options.detail == True :
                                 command = '/usr/local/bin/doveadm -D 
sync -u %s -d -N -l 30 -U' %user.split(' ')[0]
                                 print (command)
                                 command = commands(command)
                                 command = command.output.split('\n')
                                 print (command)
                                 print ('Processed Mailbox for ... %s' 
%user.split(' ')[0] )
                                 synced.append('Processed Mailbox for 
... %s' %user.split(' ')[0])
                                 for nnn in range(len(command)):
                                         synced.append(command[nnn] + '\n')

                         if options.detail == False :
                                 #command = '/usr/local/bin/doveadm -D 
sync -u %s -d -N -l 30 -U' %user.split(' ')[0]
                                 #print (command)
                                 #command = os.system(command)
                                 command = subprocess.Popen( 
["/usr/local/bin/doveadm sync -u %s -d -N -l 30 -U" %user.split(' ')[0] ], \
                                 shell = True, stdin=None, stdout=None, 
stderr=None, close_fds=True)

                                 print ( 'Processed Mailbox for ... %s' 
%user.split(' ')[0] )
                                 synced.append('Processed Mailbox for 
... %s' %user.split(' ')[0])

if len(synced) != 0 :
         #send email showing bad synced boxes ?

         if options.send_to != None :
                 send_from = 'monitor at'
                 send_to = ['%s' %options.send_to]
                 send_subject = 'Dovecot Bad Sync Report for : %s' 
                 send_text = '\n\n'
                 for n in range (len(synced)) :
                         send_text = send_text + synced[n] + '\n'

                 send_files = []
                 sendmail (send_from, send_to, send_subject, send_text, 


second :

i posted this a month ago - no response

please appreciate that i am trying to help ....

after much testing i can now reporduce the replication issues at hand

I am running on freebsd 12 & 13 stable (both test and production servers)

sdram drives etc ...

Basically replication works fine until reaching a folder quantity of ~ 
256 or more

to reproduce using doveadm i created folders like

and so forth ......

I created 200 folders and they replicated ok on both servers

I created another 200 (400 total) and the replicator got stuck and would 
not update the mbox on the alternate server anymore and is still 
updating 4 days later ?

basically replicator goes so far and either hangs or more likely bails 
on an error that is not reported to the debug reporting ?

however dsync will sync the two servers but only when run manually (ie 
all the folders will sync)

I have two test servers avaliable if you need any kind of access - again 
here to help.

[07:28:42] [root:0] ~
# sync.status
Queued 'sync' requests        0 

Queued 'high' requests        6 

Queued 'low' requests         0 

Queued 'failed' requests      0 

Queued 'full resync' requests 0 

Waiting 'failed' requests     0 

Total number of known users   255 

username                       type        status
paul at                   normal      Waiting for dsync to finish
keith at               incremental Waiting for dsync to finish
ed.hanna at           incremental Waiting for dsync to finish
ed at                     incremental Waiting for dsync to finish
nick at                incremental Waiting for dsync to finish
paul at             incremental Waiting for dsync to finish

i have been going through the c code and it seems the replication gets 
requested ok

replicator.db does get updated ok with the replicated request for the 
mbox in question.

however i am still looking for the actual replicator function in the 
lib's that do the actual replication requests

the number of folders & subfolders is defanately the issue - not the 
mbox pyhsical size as thought origionally.

if someone can point me in the right direction, it seems either the 
replicator is not picking up on the number of folders to replicat 
properly or it has a hard set limit like 256 / 512 / 65535 etc and stops 
the replication request thereafter.

I am mainly a machine code programmer from the 80's and have 
concentrated on python as of late, 'c' i am starting to go through just 
to give you a background on my talents.

It took 2 months to finger this out.

this issue also seems to be indirectly causing the duplicate messages 
supression not to work as well.

python programming to reproduce issue (loops are for last run started @ 
200 - fyi) :

# cat mbox.gen

import os,sys

from lib import *

user = 'paul at'

for count in range (0,600) :
         box = 'INBOX/folder-%s' %count
         print count
         command = '/usr/local/bin/doveadm mailbox create -s -u %s %s' 
         print command
         a = commands.getoutput(command)
         print a

for count in range (0,600) :
         box = 'INBOX/folder-0/sub-%' %count
         print count
         command = '/usr/local/bin/doveadm mailbox create -s -u %s %s' 
         print command
         a = commands.getoutput(command)
         print a


Happy Sunday !!!
Thanks - paul

Paul Kudla Internet Services <>
004-1009 Byron Street South
Whitby, Ontario - Canada
L1N 4S3

Toronto 416.642.7266
Main 1.866.411.7266
Fax 1.888.892.7266

On 4/24/2022 10:22 AM, Arnaud Abélard wrote:
> Hello,
> I am working on replicating a server (and adding compression on the 
> other side) and since I had "Error: dsync I/O has stalled, no activity 
> for 600 seconds (version not received)" errors I upgraded both source 
> and destination server with the latest 2.3 version (2.3.18). While 
> before the upgrade all the 15 replication connections were busy after 
> upgrading dovecot replicator dsync-status shows that most of the time 
> nothing is being replicated at all. I can see some brief replications 
> that last, but 99,9% of the time nothing is happening at all.
> I have a replication_full_sync_interval of 12 hours but I have thousands 
> of users with their last full sync over 90 hours ago.
> "doveadm replicator status" also shows that i have over 35,000 queued 
> full resync requests, but no sync, high or low queued requests so why 
> aren't the full requests occuring?
> There are no errors in the logs.
> Thanks,
> Arnaud

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