Hello everybody,
We are updating our old dovecot 1.1 servers to 2.0. We have a farm os servers, with users in nfs filesystems and indexes in local fs. Mail is stored in maildir format. We don't warrant that a user is always directed to the same server, although our load balancer sends all request from one IP to the same server (during a session time with a inactivity timeout). This is the second scenario described at http://wiki2.dovecot.org/NFS.
We are now trying to migrate to the third scenario and using mdbox.
As an intermediate step, we have configured this second scenario, but with indexes in NFS filesystems. The configuration is:
mmap_disable = yes
dotlock_use_excl = no
mail_nfs_storage = yes
mail_nfs_index = yes
lock_method = fcntl (we have also tried with dotlock)
This configuration works without any problems with few users, but with high load, we have a lot of lock timeouts error like:
Jun 29 10:24:04 myotis34 dovecot: imap(mpm): Error: Timeout (180s) while waiting for lock for transaction log file /home/pas/01/014601/maildir_indexes/.INBOX/dovecot.index.log
These errors cause a corrupted index and we have to manually delete the user's index so he could read his mail again.
So we are planning to configure the third scenario. In this configuration, we don't have any problem during our tests if we use maildir format. But if we use mdbox one, we have problems when we have to change the final server for the server (We allways send the user to the same final server, but sometimes, if the server is down, for example, this is not possible). The tests we have done (with POP) are:
I connect to "my" server. There's no problem. I have my mail. I delete a mail.
I connect then to a server that have no index for me. The only problem is that the previously deleted mail appears again.
I connect then to a server with an outdated index: this is the problem. I have only the messages in that outdated index. The mail received since then has disappeared (although I could receive new mail).
How could I solve this problem? Is this really a problem? Should I use a shared storage for indexes? What is the best configuration for a high availability service?
-- Angel L. Mateo Martínez Sección de Telemática Área de Tecnologías de la Información _o) y las Comunicaciones Aplicadas (ATICA) / \\ http://www.um.es/atica _(___V Tfo: 868887590 Fax: 868888337