Re: RAID config for mailboxes host

On 09/09/2011 22:52, Emmanuel Halbwachs wrote:
> We consider two RAID config for the 12 disks:
>
>          A   2 disks RAID 1 for system
>             10 disks RAID 6 for mailbox space
>
>          B  12 disks RAID 6 for the whole
>
> In A, we lose 1.2 (raw) TB with respect to B. Advocates of A say that
> in B, the heads read/write activity of the mailboxes will seriously
> impact the system performance. In A, the system has its own axes,
> separate from the mailboxes ones.

I still would go with option A -- you actually gain a lot of it.  All 
the logs and OS specific operations + MTA spools will go on a separate 
set of spindles and in some situations that helps a lot.

Make sure you get battery for the PERC controller with ideally 1GB NV 
cache -- it makes difference especially for massive amount of small 
writes which I'm sure you are going to have.

Also, I am not sure how dovecot handles fsync() however this can be pain 
in the ass if you are using ext3/4 file system which by the way is 
definitelly not the right choice in this case ;-) (what you already know 
I am sure).

I went through similar problem few months back - we were considering 
upgrading our mail server for 200+ mail accounts (~ 400 mail addresses 
in total) and we ended up... getting Google Apps for Businesses.  Highly 
recommend just having a look at it -- cost wise it looks a bit scary 
initially but you are gaining *a lot*.