Hi,
We actually have a mail hosting solutions with aprox. 100 thousand of email account, where about 90% of a customers use POP3 like email configuration. About a few mounths (we perfomed a lot of migration throught mbox email software to Maildir with dovecot) but i can see that the performance is very poor and receive complaint about delays of autentications of accounts.
The solution lives in Metrocluster Netapp storage, filesystem NFS, VMware as a virtualization (the mtas are a virtual machines lives in netapp too) about 4T of data mails and a 10G network connection (betwen mtas and nfs storage) All account information work in LDAP plataform (two servers in replicated mode, no high average or delays detected in this servers)
When the traffic have a peak of 1800 concurrent connections POP3, all of service suffer a high load average (about 8 - 20 load average in each dovecot) and authenticacion takes about 2 -10 seconds (in low traffic, autenticacion takes about 60 miliseconds)
Also, each dovecot instance lives un MTA server CentOS 5.8 x86_64 with 6G RAM (virtual machine) and share's hardware with a exim instance, like a MTA relay system (autenticated relay)
Usage of network have peaks of 80Mbits (all dmz network have 1Gbits of bandwith)
Attach of dovecot -n output:
# 2.0.18: /etc/dovecot/dovecot.conf # OS: Linux 2.6.18-308.1.1.el5 x86_64 CentOS release 5.8 (Final) auth_debug_passwords = yes auth_default_realm = portalplata.cl auth_realms = portalplata.cl auth_verbose = yes auth_verbose_passwords = plain auth_worker_max_count = 100 base_dir = /var/run/dovecot/ debug_log_path = /var/log/dovecot.log default_process_limit = 200 default_vsz_limit = 512 M disable_plaintext_auth = no first_valid_gid = 12 first_valid_uid = 8 lock_method = dotlock login_greeting = Dovecot mta10 mail_cache_min_mail_count = 5 mail_debug = yes mail_fsync = always mail_full_filesystem_access = yes mail_gid = 12 mail_location = maildir:%h/Maildir:INDEX=/data/cache/indexes/%2d/%1u/%2u/%u mail_nfs_storage = yes mail_plugins = " quota" mail_uid = 8 maildir_copy_with_hardlinks = no passdb { args = /etc/dovecot/dovecot-ldap.conf.ext driver = ldap } plugin { mail_log_events = delete undelete expunge copy mailbox_delete mailbox_rename mail_log_fields = box from subject quota = maildir } postmaster_address = mail@mail.com protocols = imap pop3 sendmail_path = /usr/lib/sendmail service auth { unix_listener auth-userdb { mode = 0600 user = exim } } service imap-login { service_count = 0 } service imap-postlogin { executable = script-login /usr/local/bin/postlogin.sh user = root } service imap { executable = imap imap-postlogin } service pop3-login { inet_listener pop3s { port = 995 ssl = yes } service_count = 0 } service pop3 { process_limit = 1024 } ssl_cert =
Output of account information in a LDAP:
# nettester, email.net, MAIL, USERS, cl dn: uid=nettester,dc=email.net,o=MAIL,o=USERS,c=cl dc: email.net mailMessageStore: /export/mdir/3/12/nettester@email.net/Maildir uid: nettester cn: nettester@email.net sn: nettester@email.net gidNumber: 12 homeDirectory: /export/mdir/3/12/nettester@email.net mail: nettester@email.net uidNumber: 8 objectClass: mailUser objectClass: posixAccount objectClass: mailSetting loginShell: /bin/false description: enable service: pop3 service: imap service2: webmail mailRate: 200 mailQuota: 1024M deliveryMode: none mailReplyText: .
Any suggestions? All ideas will be have a good receptions ;)
Pd: Sorry my english
-- Mauricio López Riffo Red Hat Certified Engineer 804006455319519 Administrador de Servicios Internet Área Ingeniería Gtd Internet S.A. http://www.grupogtd.com/ Moneda 920, Oficina 602 - Fono : +562 4139742