All Posts By

Davy Jones

Jan 20 2009
2

Nagios plugins: a two minute hate

By | Technical | One Comment

If you asked one of your friends how their parents were doing (assuming that their parents were nominally alive, and that you had an appropriate degree of friendship that permitted such social intercourse), and they replied “I’m not sure, I haven’t seen them in a while”, is it reasonable for you to reply with a statement of your condolences, on the assumption that they’re dead? No, of course not. That would be foolish. Whilst it is possible that the reason why your friend hasn’t seen them in a while is because they’re dead, and it’s possible that they’ve died without your friend being aware of it, there is no practical reason to believe that your friend’s parents are, in fact, deceased. The number and probability of the non-death-related reasons why…

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Jan 20 2009
4

New co-location suite in Global Switch

By | Company News, Technical | No Comments

On the back of a very strong 2008 for Anchor and despite the doom and gloom that has been flooding the media we’ve taken the plunge and decided to double our rack capacity in Global Switch’s Sydney facility. We’ve picked up capacity for about 29 standard (600mm wide) racks but have decided to do a fitout with the larger 750mm x 1070 mm APC server racks. The large racks should make server installation and cable management that bit easier, as well as helping with cooling. One of the nice fringe benefits of the APC racks is the oh so simple mounting of the managed power rails (which we use on all or co-location). Saves having to fiddle with custom mounting brackets. We’re hoping this new space will see us through…

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Jan 20 2009
2

Deep Bug Hunting

By | Technical | No Comments

As practically anyone who has spent more than a couple of hours of their life using computer can attest, software is not the most reliable of human creations. Most software is very, very buggy, to the point that small errors and irritations happen so often that most people’s instinctual reaction is either to ignore them, or just apply an almost-instinctual workaround. The cause of most bugs that aren’t ignorable are solidly at the “trivial” end of the scale, too — a config problem, usually, or at worst a fairly trivial logic bug, where the symptoms and logging information point quite clearly to the source of the problem. However, every once in a while, something really vicious comes along, and it’s those bugs that make people really, really glad that they’ve…

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Jan 20 2009
3

Keeping your kernel output safe

By | Technical | No Comments

Keeping logs of the operation of your system(s) is really important; when something goes wrong in the middle of the night, a good log can give you all the information you need to diagnose and fix the problem before it happens again. One area of your system that’s quite crucial to keep, but which is often forgotten, is your kernel’s dmesg output. This is all of the messages that come direct from the kernel, from “filesystem mounted” to “Aiee! Penguins on the SCSI bus!” or “lp0: on fire”. While the former isn’t so important to keep for posterity, when the kernel crashes, you really do want to capture that output, but you can’t use your system’s normal logging because when the kernel dies, it usually takes userland processes like syslogd…

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Jan 20 2009
2

….So you think you have a spam problem?

By | Technical | No Comments

Earlier today we started seeing multiple monitoring alerts from our network monitoring station suggesting that two mail servers which we manage were under considerable amounts of system load. This became so bad that email began to be delayed and in some occasions clients attempting to connect via pop and imap were timing out… meaning that mail was unable to be retrieved … This is strange behavior and something that is really only going to occur when the system is under considerable amounts of load. Subsequently, after completing an amount of investigation it appeared that the vast majority of the mail was destined for one specific domain, and addressed to some really suspect emails addresses which were never likely to exist such as: [email protected] – It seemed as though that email…

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Dec 11 2008
3

Web hosting statistics vs Google Analytics

By | Company News, Technical | No Comments

We get the request from time to time, “can you track XYZ in the website statistics for our web hosting?” We get a bit of “Your statistics reports aren’t very pretty”. We include two very commonly used statistics generators with all shared web hosting, AWStats and Webalizer. Both of these tools generate statistics using the logs that the web server keeps for every page request. These logs look something like this: 88.179.0.194 – – [11/Dec/2008:04:48:03 +1100] “GET / HTTP/1.1” 302 20 “http://www.google.fr/search?hl=fr&q=anchor+blog&start=10&sa=N” “Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.5; fr; rv:1.9.0.4) Gecko/2008102920 Firefox/3.0.4” Without explaining the log file in detail, in summary, the above line tells us: What IP address each request comes from The date and time of the request If the user clicked on a link to…

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Dec 09 2008
3

End of Year Support Hours

By | Company News | No Comments

Unfortunately as much as we’d like to to let the servers fend for themselves over the end of year period whilst we take a well earned break we can’t, there’s always someone that forgets a password or decides to break their website during the holiday period. Anchor will be available on all business days – that excludes public holidays and weekends over the break. We will operate on reduced staff numbers on other days reflecting the reduced support load. There will be a provisioning embargo in place for dedicated servers and co-location services between the 17th of December and the 5th of January 2009. Note that this embargo only applies to provision of new services – it does not effect support of existing services. Throughout the holiday period – dedicated…

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Dec 04 2008
2

How not to handle errors: phpmyadmin edition

By | Technical | No Comments

The user does something that fails, due to server-side problems, and you wish to inform the user of this problem so it can be fixed. You redirect to a page with a URL something like /error.php?message=Something+has+gone+wrong.+Please+fix+it+and+try+again The user fixes the error on the server, and (since staring at the location bar isn’t a whole lot of fun) simply hits ‘reload’ in their browser. This causes much wailing and gnashing of teeth, as the problem apparently persists. I’ll give phpMyAdmin partial credit for at least HTML escaping their errors, but… the stupid, it BURNS!

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