[Dovecot] Virtual Servers

[Patrick Domack]

I wouldn't worry about *duplicate cache* as far as disk goes at all.

This duplicate cache is only going to benifit your vm, if the host  
machine has enough left over ram. If the host machine doesn't have  
enough ram, there won't be any cache to worry about. I think this also  
only applies when using a file based drive, where if you use a raw  
partition it doesn't get cached, cause the vfs is bypassed.


Quoting "Daniel L. Miller" <dmiller at amfes.com>:

> Maybe a little off-topic - but I hope not too much.
>
> Looking for some insight on setting up Dovecot under a virtual  
> server.  In particular, I use VirtualBox - and at the moment, Ubuntu  
> Linux.
>
> Initial questions on configuration:
>
> Caching.  It seems to me - and I'm probably wrong - that running a  
> Linux in a VM on a Linux host, there would be a duplication of  
> caching.  That is, the host server has a file cache - and the VM,  
> which is otherwise a standard Linux installation, is also going to  
> try to cache its files.  This strikes me as a duplication of effort  
> and waste of RAM.  Is this something I should devote any time to  
> thinking about and trying to minimize?  If so, how?
>
> Mail storage.  My current mail store is a RAID-10, using the mdbox  
> format.  I wish to continue storing the mail on "raw" disks - not  
> place the mail inside a virtual disk.  Accordingly, the VM needs to  
> reach the mail outside the VM environment - which according to  
> conventional wisdom means NFS.  My initial testing shows NFS results  
> in a dramatically reduced performance for Dovecot.  Given that this  
> NFS access is going to be exclusively for Dovecot, and I'm only  
> running a single server, are there any NFS or Dovecot tweaks I  
> should implement?  Is there an alternative connectivity for the  
> VirtualBox environment I should explore?
>
> -- 
> Daniel