[Dovecot] Mount options and NFS: just checking...

[Mike Brudenell]

Greetings -

I'm now in the last couple of weeks before going live with Dovecot  
(v1.0.3) on our revamped IMAP service.  I'd like to double-check  
about the best mount options to use; could someone advise, please?

I have three separate directory trees for the message store, the  
control files and the index files.  These are arranged as follows:

Message Store
     Mounted over NFS from a NetApp filer; filestore quotas are ENABLED.

Control Files
     Mounted over NFS from the NetApp filer; filestore quotas are  
DISABLED.

Index Files
     Mounted on local disk; filestore quotas are DISABLED.

We will have a pair of Solaris 10 servers on which Dovecot 1.0.3 is  
running.  Users are normally directed to their "preferred" server  
but, if it is unavailable, will go via the other server.

Q1.  Am I right in thinking that for the Message Store and Control Files
      I should NFS-mount both of them with the "actimeo=0"?

      (Or would "noac" be better, which also turns off client write- 
caching
      as well as the attribute cache?)

Q2.  Should I NFS-mount either or both of the Message Store and  
Control Files
      with the "noxattr" option to turn off extended attributes?

Q3.  Which of the filestores should I mount with the "noatime" option?
      (I understand that for the filer-based NFS mounts this can be  
done on the
      filer, as the option isn't available with "mount" for NFS-monted
      filestores.)

Q4.  Any other options to use/miss out?


Currently my understanding from the list and the NFS page at the Wiki  
is:

A1.  Use "actimeo=0" for both Message Store and Control Files.
      No idea about the need for/impact of using "noac".

A2.  No idea.

A3.  Safe to use "noatime" for all three filestores.
      (I understand Dovecot will use utime() when needed on such  
filestores,
      but am not sure if it will work on the NFS-mounted filestores  
from the
      filer if access times are turned off at the filer end.)

Any thoughts, please?

Cheers,
Mike B-)

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