dovecot - Oct 2013 - couple of errors on new setup

I have stood up a new test mail server as an upgraded version of my existing
mail server.
I have been fairly consistently getting two types of error messages.
I'm thinking they may be related permissions issues, but I can't figure
out what their problem is.

Oct  4 12:45:47 digory dovecot: imap(guenther): Error: file_dotlock_open()
failed with file /home/guenther/mail/ForUs/.imap/Home/dovecot.index.log:
Resource temporarily unavailable


Oct  4 12:46:16 digory dovecot: imap(guenther): Error:
file_dotlock_open(/home/guenther/mail/ForUs/PCS/.imap/PCS
misc/dovecot.index.log) failed: Permission denied (euid=500(guenther)
egid=500(guenther), access(/home/guenther/mail/ForUs/PCS/.imap/PCS
misc/dovecot.index.log, 4) failed: No such file or directory)

Here are my specifics:

OS:  CentOS 6.4 - 2.6.32-358.11.1.el6.x86_64
MailScanner: 4.84.6
Postfix: 2.6.6
DoveCot: 2.2.4
NFS v4  (both the mail spool and /home are NVS v4 mounts to file server)

Here are the non-default settings:

dovecot -n

# 2.2.4: /etc/dovecot/dovecot.conf
# OS: Linux 2.6.32-358.11.1.el6.x86_64 x86_64 CentOS release 6.4 (Fina
auth_verbose = yes
disable_plaintext_auth = no
mail_access_groups = users,guenther
mail_location = mbox:~/mail:INBOX=/var/spool/mail/%u
mail_privileged_group = mail
mbox_write_locks = fcntl
namespace inbox {
  inbox = yes
  location   mailbox Drafts {
    special_use = \Drafts
  }
  mailbox Junk {
    special_use = \Junk
  }
  mailbox Sent {
    special_use = \Sent
  }
  mailbox "Sent Messages" {
    special_use = \Sent
  }
  mailbox Trash {
    special_use = \Trash
  }
  prefix }
passdb {
  driver = pam
}
service auth {
  unix_listener /var/spool/postfix/private/auth {
    group = postfix
    mode = 0666
    user = postfix
  }
}
ssl_cert = </etc/postfix/ssl/xxxxxxxxxx.crt
ssl_key = </etc/postfix/ssl/xxxxxxxxxx.key
userdb {
  driver = passwd
}
verbose_ssl = yes


Thanks -- Dean Guenther

On 06/10/2013 03:16, Dean Guenther wrote:


> mail_location = mbox:~/mail:INBOX=/var/spool/mail/%u
> mail_privileged_group = mail
> mbox_write_locks = fcntl

mbox over NFS has *never* been recommended, it is unsafe - for any 
pop/imap type server, not just dovecot. If its not too late, and since 
you are testing a new server it cant be, change to Maildir, it was 
designed specifically for this very reason.


also should use:

mail_fsync = yes
mail_nfs_index = yes
mail_nfs_storage = yes
mmap_disable = yes