My typical set up — 2 email servers for all of my domains. One primary with local delivery, and another one as a backup MX. Then for all my other servers, MTA is installed but either bound only to localhost, or external access to port 25 firewalled. Emails will be sent out from these servers but they shall never receive any from emails, i.e. they are all null mailer. Just in case I mis-configured the MTA and opened them up for relaying, I firewalled all SMTP access.

Well, it has actually caused more problems than I have originally envisioned.

I have been using Cacti, a RRDTool-based graphing solution, to monitor my servers/VPS over the last year or two (and before that, with MRTG). My needs are simple — I just need graphing of several server metrics and Cacti fits the bill perfectly when the data is well supplied. Cacti is installed on one of my servers, and it will pull stats from my other servers all around the globe at 5 minutes interval.

Data collection from the actual servers is another story. Usually I need

• Number of bytes transmitted and received on all network interfaces except local.
• Current load average over 1 minute, 5 minutes and 15 minutes.
• Current memory usage.

This review is a follow up from my previous blog entry. Long story short — I have been a customer of VPSLink for 17 months and have been using their OpenVZ VPS to host various projects. Recently they launched their Xen VPS hosting product, and Cameron from VPSLink has provided me a Xen Link-3 account to play around.

Before I go on, I feel that I might need to make some disclaimer. VPSLink has also been a regular sponsor of this blog since June this year (in case you have not spotted their skyscraper ads on the right), but I will try to keep my review unbiased :) I was going to give their Xen beta program a try any way when it was announced 2 months ago, but was too busy to do so.

I have been a VPSLink customer for about as long as they have been offering the service — since June 2006 I think — although I rarely blogged about them here. Recently I had an opportunity to test out their recently launched Xen VPS hosting. VPSLink now offers both OpenVZ and Xen based VPS hosting at the same price point, and I will be reviewing their Xen offering here shortly. However I would like to look into an obvious question — Xen or OpenVZ VPS — which one is suitable for me? I will be looking at the differences between Xen and OpenVZ especially in memory model, and how it is affecting us the VPS customers.

Downtime sucks, but it sort of reminded you how good it has been. HostingFu, along with about a dozen other sites hosted on this SliceHost VPS, were down between 8pm and 10pm AEST last night, when traffic is about the busiest from Australia. No good. Maybe that is one reason for hosting locally in Australia so the datacentre won’t schedule network maintenance at inconvenient time. Then I feel sorry for the now gang-of-four at SliceHost as the network dropped out at 4AM in the morning, CST time!

Here is the network graph generated by Cacti.

Two events this week that just made hosting business in Australia a bit tougher.

1. Weakening US Dollar

Australian dollar has just hit 93 cent USD today, and it is still on its way to parity (which I doubt will happen but I can be very wrong). Everything has already been more expensive in Australia than in US, and strong Aussie dollar + weak US dollar has just made the gap even wider.