[Dovecot] Rebuilding indexes fails on inconsistent mdbox

[Stan Hoeppner]

On 10/24/2012 9:45 AM, Charles Marcus wrote:
> On 2012-10-24 10:01 AM, Stan Hoeppner <stan at hardwarefreak.com> wrote:
>> If the box is truly unresponsive, i.e. hard locked, then the corrupted
>> indexes are only a symptom of the underlying problem, which is unrelated
>> to Dovecot, UNLESS, the lack of responsiveness was due to massive disk
>> access, which will occur when rebuilding indexes on a 6.6GB mailbox.
>> You need to know the difference so we have accurate information to
>> troubleshoot with.
> 
> Hmmm... I wonder would it be possible for dovecot to automatically lower
> the 'niceness' for index rebuilds (on systems that support such) to
> avoid causing such distress?

Changing the process priority would not help.  Indexing a large mailbox
is an IO bound, not a compute bound, operation.  With Linux, changing
from the CFQ to deadline scheduler may help some with low
responsiveness.  But the only real solution for such a case where iowait
is bringing the system to its knees is to acquire storage with far
greater IOPS and concurrent IO capability.  I.e. a server.

-- 
Stan