Hi,

I'll try to keep short. My primary question is what, in people's experience, are the best configuration settings for to avoid potential NFS cache locking issues in an interesting heterogeneous environment? We appear to have a workaround for some locking issues we have seen, which is turning off IDLE. Upgrading our version of dovecot from 1.1.4 is likely to address some core issues, but I want to get the system setup in tune first. There are some things in our setup that seem dumb, and I would like to make sure they are dumb.

As far as our environment goes, it isn't unusual for our users to connect with multiple different clients from multiple locations. Some of these clients behave well, and some not so well. In addition we have multiple distributed servers with multiple instances. Generally the connection from one of their clients/desktops goes to the same server but their different desktops may connect to different servers.

If anyone has a similar enough environment, do you find it better to have the hard link setting off or is it better for you to turn it on?

The attribute cache is the default (60 seconds) which works well enough in a polling setting but may be a problem with IDLE (30 second check). Do you find it better to bump up the IDLE check interval or drop the attribute cache? Our cache and maildir are on separate NFS volumes so we can change one without changing the other.

Our tcp timeout setting is too long (it is the default). Do you find 180-300 seconds more reasonable?

---Jack

To give some context, we have a handful of users with intermittent caching locking where the dovecot.index.cache file would simply not update. One of our internal people managed to get this problem when he was using pine (non-IDLE) with gnubiff (IDLE) from the same desktop. We haven't had any alarms since taking the brute force approach of turning off IDLE.

Unfortunately other projects are inhibiting my capacity for additional debugging at this time. Also, it isn't clear to me that we will learn anything useful since the servers do not appear to be tuned and they are only running dovecot 1.1.4.

Just for reference, below is our dovecot configutation.

disable_plaintext_auth = yes base_dir = /var/run/dovecot/imap-server-its/ protocols = imap imaps syslog_facility = local4 shutdown_clients = yes

ssl_cert_file = xxx.pem ssl_key_file = yyy.key ssl_ca_file = zzz.pem

mail_location = maildir:/var/spool/maildir/%1Ln/%Ln:INDEX=/var/spool/dovecot/indexes/%1Ln/%Ln

login_greeting_capability = no verbose_proctitle = yes mail_debug = yes imap_capability = "IMAP4rev1 SASL-IR SORT THREAD=REFERENCES MULTIAPPEND UNSELECT LITERAL+ CHILDREN NAMESPACE LOGIN-REFERRALS UIDPLUS LIST-EXTENDED I18NLEVEL=1"

# MAILDIR Performance settings maildir_copy_with_hardlinks = yes maildir_copy_preserve_filename = no

# Handling web logins & imap traffic login_processes_count = 16 login_max_processes_count = 2048 max_mail_processes = 4096 mail_max_userip_connections = 2000

# NFS settings mmap_disable = yes fsync_disable = no mail_nfs_index = yes mail_nfs_storage = yes dotlock_use_excl = yes

lock_method =fcntl

protocol imap { listen = *:10143 ssl_listen = *:10993 imap_client_workarounds = delay-newmail outlook-idle netscape-eoh }

## Authentication processes

namespace private { separator = . prefix = Mail. inbox = yes }

auth_verbose = yes

auth default { mechanisms = plain login

passdb ldap { args = /etc/dovecot.conf-ldap } userdb static { args = uid=vmail gid=mail home=/var/spool/maildir/%1Ln/%Ln }

socket listen { master { path = /var/run/dovecot/imap-server-its/auth-master user = vmail group = mail } user = root }