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Rajesh M

2015-Sep-12 18:53 UTC

concerning dovecot settings for high volume server

hi

centos 6 64 bit

hex core processor with hyperthreading ie display shows 12 cores
16 gb ram
600 gb 15000 rpm drive

we are having around 4000 users on a server


i wish to allow 1500 pop3 and 1500 imap connections simultaneously.

need help regarding the settings to handle the above

imap-login, pop3-login
imap pop3 service settings

i recently i got an error 
imap-login: Error: read(imap) failed: Remote closed connection (process_limit
reached?)


my current dovecot config file

# 2.2.7: /etc/dovecot/dovecot.conf
# OS: Linux 2.6.32-431.23.3.el6.x86_64 x86_64 CentOS release 6.5 (Final)
auth_cache_negative_ttl = 0
auth_cache_ttl = 0
auth_mechanisms = plain login digest-md5 cram-md5
default_login_user = vpopmail
disable_plaintext_auth = no
first_valid_gid = 89
first_valid_uid = 89
log_path = /var/log/dovecot.log
login_greeting = ready.
mail_max_userip_connections = 50
mail_plugins = " quota"
managesieve_notify_capability = mailto
managesieve_sieve_capability = fileinto reject envelope encoded-character
vacation subaddress comparator-i;ascii-numeric relational regex imap4flags copy
include variables body enotify environment mailbox date ihave
namespace {
  inbox = yes
  location   prefix   separator = .
  type = private
}
passdb {
  args = cache_key=%u webmail=127.0.0.1
  driver = vpopmail
}
plugin {
  quota = maildir:ignore=Trash
  quota_rule = ?:storage=0
}
protocols = imap pop3
service imap-login {
  client_limit = 256
  process_limit = 400
  process_min_avail = 4
  service_count = 0
  vsz_limit = 512 M
}
service pop3-login {
  client_limit = 1000
  process_limit = 400
  process_min_avail = 12
  service_count = 0
  vsz_limit = 512 M
}
ssl_cert = </var/qmail/control/servercert.pem
ssl_dh_parameters_length = 2048
ssl_key = </var/qmail/control/servercert.pem
userdb {
  args = cache_key=%u quota_template=quota_rule=*:backend=%q
  driver = vpopmail
}
protocol imap {
  imap_client_workarounds = delay-newmail
  mail_plugins = " quota imap_quota"
}
protocol pop3 {
  pop3_client_workarounds = outlook-no-nuls oe-ns-eoh
  pop3_fast_size_lookups = yes
  pop3_lock_session = no
  pop3_no_flag_updates = yes
}


thanks very much,

rajesh

Tony Morehen

2015-Sep-12 21:57 UTC

head link

concerning dovecot settings for high volume server

You may be running up against Linux system/user limits.  Run
$ cat /proc/sys/kernel/pid_max
and
$ ulimit -a
That should give some insight into your problem.

On 12/09/2015 2:53 PM, Rajesh M wrote:> hi
>
> centos 6 64 bit
>
> hex core processor with hyperthreading ie display shows 12 cores
> 16 gb ram
> 600 gb 15000 rpm drive
>
> we are having around 4000 users on a server
>
>
> i wish to allow 1500 pop3 and 1500 imap connections simultaneously.
>
> need help regarding the settings to handle the above
>
> imap-login, pop3-login
> imap pop3 service settings
>
> i recently i got an error
> imap-login: Error: read(imap) failed: Remote closed connection
(process_limit reached?)
>
>
> my current dovecot config file
>
> # 2.2.7: /etc/dovecot/dovecot.conf
> # OS: Linux 2.6.32-431.23.3.el6.x86_64 x86_64 CentOS release 6.5 (Final)
> auth_cache_negative_ttl = 0
> auth_cache_ttl = 0
> auth_mechanisms = plain login digest-md5 cram-md5
> default_login_user = vpopmail
> disable_plaintext_auth = no
> first_valid_gid = 89
> first_valid_uid = 89
> log_path = /var/log/dovecot.log
> login_greeting = ready.
> mail_max_userip_connections = 50
> mail_plugins = " quota"
> managesieve_notify_capability = mailto
> managesieve_sieve_capability = fileinto reject envelope encoded-character
vacation subaddress comparator-i;ascii-numeric relational regex imap4flags copy
include variables body enotify environment mailbox date ihave
> namespace {
>    inbox = yes
>    location >    prefix >    separator = .
>    type = private
> }
> passdb {
>    args = cache_key=%u webmail=127.0.0.1
>    driver = vpopmail
> }
> plugin {
>    quota = maildir:ignore=Trash
>    quota_rule = ?:storage=0
> }
> protocols = imap pop3
> service imap-login {
>    client_limit = 256
>    process_limit = 400
>    process_min_avail = 4
>    service_count = 0
>    vsz_limit = 512 M
> }
> service pop3-login {
>    client_limit = 1000
>    process_limit = 400
>    process_min_avail = 12
>    service_count = 0
>    vsz_limit = 512 M
> }
> ssl_cert = </var/qmail/control/servercert.pem
> ssl_dh_parameters_length = 2048
> ssl_key = </var/qmail/control/servercert.pem
> userdb {
>    args = cache_key=%u quota_template=quota_rule=*:backend=%q
>    driver = vpopmail
> }
> protocol imap {
>    imap_client_workarounds = delay-newmail
>    mail_plugins = " quota imap_quota"
> }
> protocol pop3 {
>    pop3_client_workarounds = outlook-no-nuls oe-ns-eoh
>    pop3_fast_size_lookups = yes
>    pop3_lock_session = no
>    pop3_no_flag_updates = yes
> }
>
>
> thanks very much,
>
> rajesh

Robert Schetterer

2015-Sep-13 06:13 UTC

head link

concerning dovecot settings for high volume server

Am 12.09.2015 um 20:53 schrieb Rajesh M:> hi
> 
> centos 6 64 bit
> 
> hex core processor with hyperthreading ie display shows 12 cores
> 16 gb ram
> 600 gb 15000 rpm drive
> 
> we are having around 4000 users on a server
> 
> 
> i wish to allow 1500 pop3 and 1500 imap connections simultaneously.
for pop3 you will have no problems, perhaps you need a little tuning
imap is different cause many clients will stay idle perhaps you should
consider a setup with loadbalancers and more then one servers


Best Regards
MfG Robert Schetterer

-- 
[*] sys4 AG

http://sys4.de, +49 (89) 30 90 46 64
Franziskanerstra?e 15, 81669 M?nchen

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Vorstand: Patrick Ben Koetter, Marc Schiffbauer
Aufsichtsratsvorsitzender: Florian Kirstein

Axel Luttgens

2015-Sep-13 06:26 UTC

head link

concerning dovecot settings for high volume server

> Le 12 sept. 2015 ? 20:53, Rajesh M a ?crit :
> 
> hi
> 
> [?]
> 
> i wish to allow 1500 pop3 and 1500 imap connections simultaneously.
> 
> need help regarding the settings to handle the above
> 
> imap-login, pop3-login
> imap pop3 service settings
> 
> i recently i got an error
> imap-login: Error: read(imap) failed: Remote closed connection
(process_limit reached?)
> 
> [?]
Hello Rajesh,

I guess you could have a look at:

	http://wiki2.dovecot.org/Services

For example, a pop3 connection requires one pop3-login process and one pop3
process (unless your are running in "high performance mode"; but this
doesn?t seem to be the case).
So, you would have to adjust the process_limit setting for both of these
services.

IIRC, those settings are by default set to 0 and thus take the value of
default_process_limit (which in turn defaults to 100).

Of course, as others have already noted, such settings must remain within the
limits configured at the system level.

HTH,
Axel

Urban Loesch

2015-Sep-13 07:33 UTC

head link

concerning dovecot settings for high volume server

Hi,

I have running dovecot with about 28k users.
Here comes my relevant config for pop3 and imap from "doveconf -n".
No problems so far.

-- snip --
default_client_limit = 2000
...

service imap-login {
   inet_listener imap {
     port = 143
   }
   process_limit = 256
   process_min_avail = 50
   service_count = 1
}
service imap {
   process_limit = 2048
   process_min_avail = 50
   service_count = 1
   vsz_limit = 512 M
}
...

service pop3-login {
   inet_listener pop3 {
     port = 110
   }
   process_limit = 256
   process_min_avail = 25
   service_count = 1
}
service pop3 {
   process_limit = 256
   process_min_avail = 25
   service_count = 1
}
...

protocol imap {
   imap_client_workarounds = tb-extra-mailbox-sep
   imap_id_log = *
   imap_logout_format = bytes=%i/%o session=<%{session}>
   mail_max_userip_connections = 40
   mail_plugins = " quota mail_log notify zlib imap_quota imap_zlib"
}

...
protocol pop3 {
   mail_plugins = " quota mail_log notify zlib"
   pop3_logout_format = bytes_sent=%o top=%t/%p, retr=%r/%b, del=%d/%m, 
\ size=%s uidl_hash=%u session=<%{session}>
}
-- snip --

Regards
Urban


Am 12.09.2015 um 20:53 schrieb Rajesh M:> hi
>
> centos 6 64 bit
>
> hex core processor with hyperthreading ie display shows 12 cores
> 16 gb ram
> 600 gb 15000 rpm drive
>
> we are having around 4000 users on a server
>
>
> i wish to allow 1500 pop3 and 1500 imap connections simultaneously.
>
> need help regarding the settings to handle the above
>
> imap-login, pop3-login
> imap pop3 service settings
>
> i recently i got an error
> imap-login: Error: read(imap) failed: Remote closed connection
(process_limit reached?)
>
>
> my current dovecot config file
>
> # 2.2.7: /etc/dovecot/dovecot.conf
> # OS: Linux 2.6.32-431.23.3.el6.x86_64 x86_64 CentOS release 6.5 (Final)
> auth_cache_negative_ttl = 0
> auth_cache_ttl = 0
> auth_mechanisms = plain login digest-md5 cram-md5
> default_login_user = vpopmail
> disable_plaintext_auth = no
> first_valid_gid = 89
> first_valid_uid = 89
> log_path = /var/log/dovecot.log
> login_greeting = ready.
> mail_max_userip_connections = 50
> mail_plugins = " quota"
> managesieve_notify_capability = mailto
> managesieve_sieve_capability = fileinto reject envelope encoded-character
vacation subaddress comparator-i;ascii-numeric relational regex imap4flags copy
include variables body enotify environment mailbox date ihave
> namespace {
>    inbox = yes
>    location >    prefix >    separator = .
>    type = private
> }
> passdb {
>    args = cache_key=%u webmail=127.0.0.1
>    driver = vpopmail
> }
> plugin {
>    quota = maildir:ignore=Trash
>    quota_rule = ?:storage=0
> }
> protocols = imap pop3
> service imap-login {
>    client_limit = 256
>    process_limit = 400
>    process_min_avail = 4
>    service_count = 0
>    vsz_limit = 512 M
> }
> service pop3-login {
>    client_limit = 1000
>    process_limit = 400
>    process_min_avail = 12
>    service_count = 0
>    vsz_limit = 512 M
> }
> ssl_cert = </var/qmail/control/servercert.pem
> ssl_dh_parameters_length = 2048
> ssl_key = </var/qmail/control/servercert.pem
> userdb {
>    args = cache_key=%u quota_template=quota_rule=*:backend=%q
>    driver = vpopmail
> }
> protocol imap {
>    imap_client_workarounds = delay-newmail
>    mail_plugins = " quota imap_quota"
> }
> protocol pop3 {
>    pop3_client_workarounds = outlook-no-nuls oe-ns-eoh
>    pop3_fast_size_lookups = yes
>    pop3_lock_session = no
>    pop3_no_flag_updates = yes
> }
>
>
> thanks very much,
>
> rajesh
>

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