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" <dmil...@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
