[Dovecot] index IO patterns

[Cor Bosman]

> 
>> Alternatively, does anyone have any experience with other redundant storage options? Im thinking things like MooseFS, DRBD, etc? 
> 
> You seem to be interested in multi-site clustering/failover solutions,
> not simply redundant storage.  These two are clustering software
> solutions but DRBD is not suitable for multi-site use, and MooseFS
> doesn't seem to be either.  MooseFS is based heavily on FUSE, so
> performance will be far less than optimal.  MooseFS is a distributed
> filesystem, and as with all other distributed/cluster filesystems its
> metadata performance will suffer, eliminating maildir as a mail store
> option.
> 
> Can you provide more specifics on your actual storage architecture needs?


There are some people in our company that like MooseFS, so i'll just
include it in the tests and let that speak for itself :) We are not looking
for multisite solutions. Then we may as well stay with the metrocluster.
I dont even care if it has to be in the same rack. It's only for the indexes,
not the mail store itself which will stay on the metrocluster.  In the very 
worst case, when the whole site explodes, i can always tell dovecot 
to use memory for indexes temporarily :)

The indexes are doing a lot of iops on the metrocluster, and it's a bit
of an expensive option for something it's not even that good at. 

Im aiming for something with 2 servers, each with a 12 disk enclosure
with SSD for fast random io with 10G network interfaces, 24 core, 48GB
memory. 

I just want to test some io patterns on different hardware/software
solutions, including the metrocluster itself, before we commit to
a specific solution. Im slightly leaning towards DRBD right now.

Cor