Partition selection algorithm and ZFS filesystems

[Nic Bernstein]

Friends,
The man page for imapd.conf contains this note (emphasis added):

    defaultpartition: <none>
    The partition name used by default for new mailboxes. *If not
    specified, the partition with the most free space will be used for
    new mailboxes.*

However, with the advent of ZFS and other filesystems with Thin 
Provisioning, it is common for all partitions to have the same amount of 
free space reported by the filesystem.  For example, this from a 
client's system with 30 data partitions and 30 meta-data partitions:

    data2/mailstore/1             4.9T     18G    4.9T     0%    /var/mailstores/1
    data2/mailstore/10            4.9T     12G    4.9T     0%    /var/mailstores/10
    data2/mailstore/11            4.9T     10G    4.9T     0%    /var/mailstores/11
    data2/mailstore/12            4.9T     16G    4.9T     0%    /var/mailstores/12
    data2/mailstore/13            4.9T     15G    4.9T     0%    /var/mailstores/13
    data2/mailstore/14            4.9T     16G    4.9T     0%    /var/mailstores/14
    ...
    data2/imapmeta/1              4.9T    1.2G    4.9T     0%    /var/imapmeta/1
    data2/imapmeta/10             4.9T    283M    4.9T     0%    /var/imapmeta/10
    data2/imapmeta/11             4.9T    370M    4.9T     0%    /var/imapmeta/11
    data2/imapmeta/12             4.9T    251M    4.9T     0%    /var/imapmeta/12
    data2/imapmeta/13             4.9T    369M    4.9T     0%    /var/imapmeta/13
    data2/imapmeta/14             4.9T    230M    4.9T     0%    /var/imapmeta/14
    ...

In light of this, we intend to have our account creation scheme base its 
choice on space used, rather than free space.  But, would it be 
possible, in light of the wide spread adoption of thin provisioned 
filesystems, to have the default behavior changed in 2.5 or some future 
version of Cyrus imapd?

Thanks in advance,
     -nic

-- 
Nic Bernstein                             nic at onlight.com
Onlight, Inc.                             www.onlight.com
219 N. Milwaukee St., Suite 2a            v. 414.272.4477
Milwaukee, Wisconsin  53202

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