[Dovecot] Finally upgrading from v1.0.15 to v1.2.16 -- advice please

It's long over due, but now I finally plan on upgrading from v1.0.15 to v1.2.16 on our servers. Would appreciate any comments!

We have 7 servers, all running of the same GPFS filesystem. Both maildirs and indexes are stored here. We use dovecot for POP/IMAP and deliver. Currently we're using mysql as authentication source, but want to move to using ldap instead.

Can we upgrade one server at a time, or do we need to upgrade all servers at the same time ? http://wiki2.dovecot.org/Upgrading/1.1 says "Index files have slightly changed as well. Upgrading to v1.1 should go transparently, but moving back to v1.0 might again cause some errors." which makes me think we can't have both versions running against the same users ?

Also, if we upgrade only one server, should we switch to "mmap_disable=no" on this one, or keep running with "mmap_disable=yes" on all servers ?

"NFS users should now set mail_nfs_storage=yes and mail_nfs_index=yes." Does this apply to any shared/networked filesystems, and is this relevant for GPFS ?

The sql queries we're doing now is:

password_query = select U.Account as user,S.Password as password from Users U, UserSession S where U.Account=S.Account and U.Account='%u'
user_query = SELECT 3000 as uid, 3000 as gid, concat(concat('maildir:', MailDir), concat(':INDEX=', replace(MailDir, '/usr/local/atmail/users', '/usr/local/atmail/users/indexes'))) as mail, concat('maildir:storage=', UserQuota) as quota FROM Users WHERE Account = '%u'

I plan on doing ldap bind() for authentication:

hosts = maildb3.example.net:389
auth_bind = yes
ldap_version = 3
base = ou=people,o=%d,o=ISP,o=example,c=net
deref = never
scope = onelevel
user_filter = (&(objectClass=altiboxperson)(uid=%n))
default_pass_scheme = SSHA

but the user_query is a challenge.. In LDAP we have:

uid = janfrode, ou=people,o=domain1.net,o=ISP,o=example,c=net
mail = janfrode@domain1.net
mailMessageStore = /usr/local/atmail/users/j/a/janfrode@domain1.net
mailQuota = 1000000
domain = domain1.net
userPassword = SSHA-string

So, outside of the user_attrs we need:

mail_uid = 3000
mail_gid = 3000

But I'm having a hard time understanding how I can use the ldap value mail=/usr/local/atmail/users/j/a/janfrode@domain1.net to translate into dovecot's "mail" containing both "maildir:" and "INDEX=".

Does the below look correct ?

user_attrs = mailMessageStore=mail=maildir:%$:INDEX=/usr/local/atmail/users/indexes/%1u/%1.1u/%u, mailQuota=quota_rule=*:storage=%$

i.e. will it point dovecot at:

mail = maildir:/usr/local/atmail/users/j/a/janfrode@domain1.net:INDEX=/usr/local/atmail/users/indexes/j/a/janfrode@domain1.net
quota_rule=*:storage=1000000

-jf