Paul McCormack’s Web Site

I do.

I am a bit particular about accurately knowing the current time so I have set up two Stratum 2 NTP time servers at home. One syncs from the atomic clocks run by the National Measurement Institute in Australia (they are the folks that define the official time in Australia) and the other connects to GPS clocks run by various Australian universities.

As a result, all computers in my home are accurate to within one thousandth of a second of the official time.

Having a pair of Stratum 2 servers and not sharing them seems a bit selfish, so I have recently registered as a member of the NTP Pool which provides public access to accurate NTP servers. If you sync from *.au.pool.ntp.org then there is a chance that you are getting time from my servers. You can also add ntp.paulmccormack.com as a server if you want.

Performance information on my server can be found here.

There is no excuse to be late any more!

As mentioned in my last post, I have migrated from Optus ADSL to TPG Naked ADSL2+. I have had a few reliability problems with the connection dropping out regularly which compounded the DNS migration issues.

TPG recommended changing the DSL modulation type to G.dmt, however my trusty NETGEAR modem/router does not have an option for this. After a short search, I found an article on the Whirlpool forums that described how to telnet onto the device and change the settings. Reading all the way to the bottom, I found a gem about an unofficial release of firmware for the NETGEAR DG834 range from DGTeam.

You see, NETGEAR did a good thing a couple of years back when they released their firmware to the community under an open source licence. The good folk at DGTeam picked up the code and have fixed numerous bugs and added functionality. Uploading the new firmware was simple and it worked straight away.

The new code has a drop down box to change the modulation type to G.dmt. The router reconnected and has been solid ever since. It has even connected at a higher speed than with the automatic setting.

Another bonus seems to be that the Asterisk SIP trunk disconnection that was occurring when the WAN IP changed seems to be working OK now. Previously, every time the modem dropped the line, my two external SIP trunks would become “UNREACHABLE” until I rebooted the server.

Another success for open source thanks to the guys at DGTeam.

I have changed ISP from Optus Business ADSL to TPG Naked ADSL2+. There have been a few problems during the transition which have prevented a smooth cut over.

The main problem has been that my new static IP address has not been configured properly by TPG despite being informed of the new address 10 days prior to activation of the line. This has meant that my IP changes frequently and the DNS lookups for my servers was failing. My web sites may appear to be down and inbound email delivery was intermittent.

I tried to avoid this problem up front by adding the new static IP to my DNS records. This was cunning foresight, but the problem with constantly changing dynamic IP addresses messed things up.

I also made an oversight with the TTL (Time To Live) settings for the DNS entries. I left these as 1 week which was far too high long as this meant that an incorrect DNS lookup could have been stored for up to a week before being re-checked. I have dropped this to 30 minutes until the IP address allocation has been fixed.

Good job I don’t change ISP very often. Sorry if you were having problems accessing our web sites in the meantime, however my upload speed has increased fourfold from 256Kb to 1Mb so the sites should load a lot quicker.

I currently run a number of home servers for various purposes (email, web, IM, NFS, PBX, calendar, MythTV, music & DNS hosting). These are running on five different systems around the house. At times, this strikes me as excessive!

Ever since VMWare launched their free server offering, I have been wanting to consolidate the number of systems, however the hindrance was always the amount of RAM that I would need to purchase to make the host run properly.

Recently, I have been thinking about the cost of electricity vs the cost of the additional RAM and I started to do some calculations. We get our electricity from Energy Australia on their SmartMeter tariff which varies the cost of the power during the day:

• Mon - Fri: 9 hours off-peak, 9 hours shoulder, 6 hours peak
• Weekend: 9 hours off-peak, 25 hours shoulder

The rates for these three tariffs are currently (per kWh):

• 8.14c off-peak
• 14.08c shoulder
• 35.64c peak (pricey)

A quick calculation works out the weekly hours as 63 off-peak, 75 shoulder and 30 peak which costs $26.38 per kW.

One of my servers (mail & NFS) is a Dell SC420 which uses about 160W when idle according to this report.

This means that one of my systems costs me $220 a year to run. That is a lot more than I thought!

I think that I can virtualise my Dell GX150 (Asterisk VOIP PBX server) and HP/Compaq EVO D510 SFF (web & IM) without too much drama. These boxes are smaller than the SC420 and the environmental reports for these are not available, but I reckon that there is a saving of $300 a year to be made by switching them off.

I have just purchased 2Gb RAM for the SC420 so that I can install and run VirtualBox without any performance problems. This will increase the current memory footprint five-fold and will easily swallow the other two servers memory requirements. Total cost for the RAM: $60.

I found a very useful article today on the MakeUseOf web site. The article goes into some detail about what you should do to safeguard your privacy when using Facebook. I have a Facebook profile, but I rarely use it, preferring to control the information that I release through this web site instead. I can control every aspect of this site and I trust myself a great deal more than I trust Facebook!

Click here to view the article. I found point 8 particularly interesting - I was unaware that applications installed by Friends have access to my profile.