On Tue, 19 Jan 2016 12:22:31 PM Craig Sanders via luv-main wrote:
On Tue, Jan 19, 2016 at 10:12:12AM +1000, Piers Rowan wrote:
- dovecot - apache (roundcube webmail) - sendmail
unless you're a sendmail expert with a decade or two of experience working with it, you might want to think about switching to postfix.
While Sendmail is generally a bad choice, it seems unlikely that it is contributing to the disk IO performance here. One thing that can be done to improve performance on the MTA side is to use Dovecot's delivery agent instead of having the MTA deliver directly or use Procmail or similar. If Dovecot delivers directly it will index the mail while delivering it which will save tim later.
You can get Samsung 850 Pro 128GB for $116. $188 for 256GB. if your total mail size is < 128GB and unlikely to grow that large in the forseeable future, you're better off with a pair of 128GB drives in RAID-1 than a single 256GB drive.
if it's a VM at a co-lo facility, talk to them about getting a host with at least one SSD so you can move your mail spool to that.
hetzner.de has some good deals on servers with SSD.
so you're regularly importing mail into a database of some sort?
that may be the source of your problem - dovecot will be contending with mysql for disk I/O unless the mysql db and the mail spool are on different disks (ideally, two separate SSDs. or two separate RAID-1 devices on SSD)
I find it difficult to imagin a mail service of that nature which needs performance that is greater than a pair of SSDs in a RAID-1 can provide. I think we're talking about a mail server for a small company not hotmail.
as russell suggested, run iostat - and run it on the host, not on the VM.
Run it on both. Generally run everything everywhere. It doesn't do any harm and you never know what you might discover. But in the specific case of iostat if the host is doing disk IO that causes delays for the VM it's something you need to know. -- My Main Blog http://etbe.coker.com.au/ My Documents Blog http://doc.coker.com.au/