[Dovecot] Significant performance problems

[Brian Hayden]

imapproxy can only take you from "doesn't work" to "might as well not work", ime. If at all possible look into a stateful web client. 

-bdh

On Oct 6, 2010, at 6:32 PM, Chris Hobbs <chobbs at nhusd.k12.ca.us> wrote:

> Hi all,
> 
> I'm sure my issues are a result of misconfiguration, but I'm hoping someone can point me in the right direction. I'm getting pressure to move us back to GroupWise, which I desperately want to avoid :-/
> 
> We're running dovecot 1.2.9 on Ubuntu 10.4 LTS+postfix. The server is a VM with 1 vCPU and 4GB of RAM. We serve about 10,000 users with anywhere from 500-1000 logged in at any one time. Messages are stored in Maildir format on two NFS servers (one for staff, the other for students).
> 
> Today I implemented the "High performance" setup described here: http://wiki.dovecot.org/NFS (mainly moving indexes off of NFS, since I'm only using the one server).
> 
> I also added imapproxy to our webmail client server (SOGo). The vast majority of our users come in over the web.
> 
> We currently see load averages spiking into the 20-30 range. When this happens, service crawls to a near standstill, and ultimately the SOGo client starts crashing out.
> 
> I'm wondering if anything jumps out at anybody here - feel free to mock if/when you find an obvious configuration problem. I just want it to work :-)
> 
> dovecot -n
> 
> # 1.2.9: /etc/dovecot/dovecot.conf
> # OS: Linux 2.6.32-25-server x86_64 Ubuntu 10.04.1 LTS
> log_timestamp: %Y-%m-%d %H:%M:%S
> protocols: imap imaps pop3 pop3s managesieve
> listen(default): *
> listen(imap): *
> listen(pop3): *
> listen(managesieve): *:2000
> ssl_cert_file: /etc/dovecot/certs/mail_nhusd_k12_ca_us.crt
> ssl_key_file: /etc/dovecot/certs/mail_nhusd_k12_ca_us.key
> disable_plaintext_auth: no
> login_dir: /var/run/dovecot/login
> login_executable(default): /usr/lib/dovecot/imap-login
> login_executable(imap): /usr/lib/dovecot/imap-login
> login_executable(pop3): /usr/lib/dovecot/pop3-login
> login_executable(managesieve): /usr/lib/dovecot/managesieve-login
> login_process_per_connection: no
> login_process_size: 512
> login_processes_count: 20
> login_max_processes_count: 3000
> login_max_connections: 64
> max_mail_processes: 2048
> mail_max_userip_connections(default): 20
> mail_max_userip_connections(imap): 20
> mail_max_userip_connections(pop3): 10
> mail_max_userip_connections(managesieve): 10
> mail_access_groups: staffmailusers
> mail_privileged_group: dovecot
> mail_uid: mail
> mail_gid: 502
> mail_location: maildir:~/Maildir:INDEX=/var/indexes/%u
> mail_nfs_storage: yes
> mbox_write_locks: fcntl dotlock
> mail_executable(default): /usr/lib/dovecot/imap
> mail_executable(imap): /usr/lib/dovecot/imap
> mail_executable(pop3): /usr/lib/dovecot/pop3
> mail_executable(managesieve): /usr/lib/dovecot/managesieve
> mail_plugins(default): acl imap_acl quota imap_quota expire
> mail_plugins(imap): acl imap_acl quota imap_quota expire
> mail_plugins(pop3):
> mail_plugins(managesieve):
> mail_plugin_dir(default): /usr/lib/dovecot/modules/imap
> mail_plugin_dir(imap): /usr/lib/dovecot/modules/imap
> mail_plugin_dir(pop3): /usr/lib/dovecot/modules/pop3
> mail_plugin_dir(managesieve): /usr/lib/dovecot/modules/managesieve
> namespace:
>  type: private
>  separator: /
>  inbox: yes
>  list: yes
>  subscriptions: yes
> namespace:
>  type: shared
>  separator: /
>  prefix: shared/%%u/
>  location: maildir:%%h/Maildir:INDEX=~/Maildir/shared/%%u
>  list: children
> lda:
>  deliver_log_format: %$ -- FROM=%f SUBJECT=%s
>  mail_plugins: cmusieve acl expire
>  log_path:
>  info_log_path:
>  syslog_facility: mail
>  postmaster_address:postmaster at nhusd.k12.ca.us
>  hostname: mail.nhusd.k12.ca.us
>  auth_socket_path: /var/run/dovecot/auth-master
> auth default:
>  passdb:
>    driver: pam
>  passdb:
>    driver: ldap
>    args: /etc/dovecot/dovecot-ldap.conf
>  userdb:
>    driver: ldap
>    args: /etc/dovecot/dovecot-ldap.conf
>  socket:
>    type: listen
>    master:
>      path: /var/run/dovecot/auth-master
>      mode: 384
> plugin:
>  quota: maildir:User quota
>  quota_rule: *:storage=9G
>  quota_rule2: Trash:storage=200M
>  acl: vfile
>  acl_shared_dict:file:/home/staff/dovecot/shared-mailboxes
>  expire: Trash 7 Trash/* 7 Spam 30
>  expire_dict: proxy::expire
>  sieve: ~/.dovecot.sieve
>  sieve_dir: ~/sieve
>  sieve_extensions: +imapflags
> dict:
>  expire: mysql:/etc/dovecot/dovecot-dict-expire.conf
> 
> 
> 
> -- 
> Chris Hobbs
> Director, Technology
> New Haven Unified School District
> 
> --
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