Hi Rajesh,
our setup looks as follows:
- we are running linux-vserver as virtualization technology
- we have 2 dedicated IMAP/POP3 Proxies in front of 8 dovecot containers.
- totally about 2900 concurrent imap sessions on each imap proxy and about 180
concurrent pop3 sessions
- all dovecot containers are running on the same hardware (no problems until
today):
DELL PER720 with 2x 200GB RAID 1 SSD's for dovecot indexes, 8x 4TB RAID 10
for maildata, 2x300GB RAID1 for OS
64GB RAM, 2x CPU E5-2640 0 @ 2.50GHz
- HA is Active/Passive with DRBD on 10GBIT dedicated NIC's for all 3
partitions.
- in summary there are about 47k accounts on it.
- 15minutes system load is between 0.5 - 2.5
- mailserver software is always postfix
- amavis with spamassassin and clamav
- opendkim, opendmarc as milter implementations
Front MX and antispam filtering is running on 2 different machines. Mail volume
is between 200k and 600k (spam inclusive) per day.
We never faced some email re-download, only if the customers changes his mail
client. But that's normal.
Hope that helps.
Best
Urban
Am 13.09.2015 um 19:35 schrieb Rajesh M:> thanks very much urban. this was very helpful.
>
> i have around 12500 users spread over 3 independent servers each having
around 4000+ users
> i am using qmailtoaster, vpopmail, spamassassin and dovecot.
>
> in future i am planning to consolidate all using a HA cluster.
>
> if it is ok with you could you kindly share some information about your
email server configuration. if you do not wish to put it on the list then you
can directly email me.
>
> 1) is your email volume high ?
> 2) server hardware to support 28000 users
> 3) mailserver software - exim or postfix ??.
> 4) antispam software like spamassassin if any
>
> also if you have faced any email re-download issues with dovecot sometimes
randomly incase of pop3 users storing emails on the server ?
>
>
> thanks
> rajesh
>
>
>
> ----- Original Message -----
> From: Urban Loesch [mailto:bind at enas.net]
> To: dovecot at dovecot.org
> Sent: Sun, 13 Sep 2015 09:33:14 +0200
> Subject: Re: 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
>>
>