Serious server rooms have large (and expensive) air-conditioning and filtering systems. Most “server rooms” however are not like that, often it’s just some space in a store-room, sometimes near printers (which are a source of air pollution [1]).

The servers that are stored in serious server rooms have air filters as a standard feature. For small server installations it’s often a desktop PC used as a server which has no filters (and often lacking other server features such as ECC RAM). Recently Dell in Australia started selling low-end PowerEdge servers for $450 plus delivery (similar machines to the $800 Dell servers I previously blogged about [2]). Also refurbished machines from HP and IBM can often be purchased at auction for similar prices.

Even if you have a proper server with filters on all air inlets it’s still a benefit to have reasonably clean air in the server area. A few years ago I bought four Sunbeam HEPA [3] air filters for my home to alleviate allergy problems. I’ve had one running 24*7 in my main computer area for most of the time since then. As well as wanting to keep my machines free of dust I have the extra issue of machines that I buy at auction which often are filled with dust – the process of cleaning them frees some dust in the air and it’s good to have a filter running to remove it.

Excessive dust in the air can prevent cooling fans from operating and cause damage to hardware and loss of data. Of course the really good servers have fan speed sensors that allow the CPU to be throttled or the machine to be halted in case of severe problems. But for desktop machines you often only have the temperature control mechanisms that are built in to the CPU and sometimes machines just start having memory errors when the fan malfunctions and the machine gets hot.

As one of the biggest problems facing server rooms is heat dissipation I decided to measure my air filters and see how much electricity they use (it seems reasonably to assume that all their energy eventually gets converted to heat). I’ve now got a blog page about power use of items related to computers [4]. My air filters take 114W when on the highest speed and 13.9W when on the lowest. Initially I was a little surprised at the figure for the high speed, but then I recalled that the energy required to move air is proportional to the speed cubed. I’ll just have to make sure I don’t leave an air filter on overnight in summer…

I’m now going to recommend such filters to some of my clients. Spending $400 on an air filter is nothing compared to the amount of money that a server failure costs (when you have expensive down-time and pay people like me to fix it).

• [1] http://www.computeractive.co.uk/computeractive/news/2195474/laser-printer-research-worrying
• [2] http://etbe.coker.com.au/2007/08/25/designing-computers-for-small-business/
• [3] http://en.wikipedia.org/wiki/Hepa
• [4] http://doc.coker.com.au/environment/computer-related-power-use/

Yesterday I received an unsigned notice in the mail from some residents of an area comprising my street and an adjacent one. They advised me that their children were going to do the Halloween thing and that if I wanted to be involved I should leave my porch light on. This is a really good idea, people who like that sort of thing can leave their light on and give lollies to children (whatever happened to “don’t take lollies from strangers”?). People who don’t like pagan festivals can leave their porch light off and not be bothered.

One thing that occurred to me is that the anonymous flyer might have been posted by someone who doesn’t like Halloween to provide a way for themselves and like-minded people to opt-out of it. I’m sure that everyone told their children not to knock on a door unless there is a porch light on.

It’s almost 10PM and no-one has rung my doorbell, it seems to have worked.

I’ve just started getting a lot of traffic referred by live.com. It seems that my post Porn for Children [1] is the second link returned from a live.com search for “porn” and my post Porn vs Rape [2] is the third link. These results occur in two of the three settings for “safe search” (the most safe one doesn’t return any matches for a query about “porn”). A query for “porn” and “research” (which would reasonably be expected to match a blog post concerning scientific research made my page the 8th listing (behind http://www.news.com.au/404, http://www.news.com.au/couriermail/404, and http://www.theaustralian.news.com.au/404). It seems strange that a query which should match my page gives it a lower ranking than three 404 error pages while a query which shouldn’t match my page (no-one who searches for “porn” on it’s own wants to read about scientific research) gives it a high ranking.

One very interesting thing about the live.com search is that it doesn’t filter out some of the least effective ways of gaming search engines. For example the URL http://gra.sdsu.edu/research.php has a huge number of links to porn pages and pages that apparently sell illegal pharmecuticals) that are not visible (view page source to see them). The links that I tested were all broken so it seems that the other sites (including http://www.hcs.harvard.edu/~hraaa, http://base.rutgers.edu/pgforms, http://www.wccs.edu/employees, http://base.rutgers.edu/mirna, http://www.calstatela.edu/faculty/jperezc/students/oalamra, and http://institute.beacon.edu/), were cleaned up long ago. There is probably some money to be made in running a service that downloads all content from a web site and/or has a firewall device that sniffs all content that is sent out and makes sure that it seems to be what is intended (about half the URLs in question appear to relate to content that is illegal under US law).

As an aside, I did a few other live.com searches for various sites and the word “porn” and found one Australian university running a forum with somewhat broken HTTP authentication that has some interesting posts about porn etc. I’m not going to provide a link because the content didn’t appear to violate Australian law and you expect some off-topic content on a forum.

But to be fair, live.com have significantly improved their service since last time I tested it [3]. Now a search for “bonnie” or “bonnie++” will give me the top two spots which is far better than the previous situation. Although I have to admit that the Google result of not giving me a high ranking for “bonnie” is probably better.

• [1] http://etbe.coker.com.au/2007/08/12/porn-for-children/
• [2] http://etbe.coker.com.au/2007/07/30/porn-vs-rape/
• [3] http://etbe.coker.com.au/2007/04/02/livecom-malware/

I often get reports such as “the server was dead so I rebooted it“. This really doesn’t help me fix the problem, so if the person who uses the server wants reliability (and doesn’t want to be rebooting it and losing data all the time) then more information needs to be provided. Here is a quick list of tests to perform before a reboot if you would like your server not to crash in future:

1. Does pressing the CAPS-LOCK key on the keyboard make the CAPS LED light up? If so then the OS isn’t entirely dead.
2. What is on the screen of the server (you may have to press a key to get the screen to un-blank)? If it’s a strange set of numbers then please photograph them if possible, I might understand what they mean. If you don’t have a camera with high enough resolution to capture them then please make a note of some of the messages. Don’t write down numbers – they are not useful enough to be worth the effort. Write down words, including special words such as OOM and pairs of words seperated by a “_” character.
   If the “server” is a Xen virtual machine then save the contents of the console (as described in my previous post [1]).
3. Can you ping the machine (usually by ping servername)? If so then networking is basically operational.
4. Are the hard drive access lights indicating heavy use? If so then it might be thrashing due to excessive memory use (maybe a DOS attack).
5. Can you login at the console? If so please capture the output of free, ps auxf, and netstat -tn.
6. If the machine offers TCP services (almost all servers do) then use the telnet command to connect to the service port and make a note of what happens. For example to test a mail server type “telnet server 25” and if all goes well you expect to see “220 some message from the mail server“, note how long it takes for such a message to be displayed. Some protocols don’t send a message on a connect, for example with HTTP (the protocol used by web servers) you have to enter a few characters and press ENTER to get a response (usually some sort of HTTP error message).

Finally please don’t tell me that the server is too important and that the users couldn’t wait for you to perform any tests before rebooting it. If the server is important then it is important that it doesn’t crash repeatedly. A crash may even be caused by something that could cause data loss (EG hardware that is failing) or something that could incur extra expense if not fixed quickly (EG failing hardware that will be out of warranty soon). You have to tell users that the choice is to wait for an extra few minutes or risk having another crash tomorrow with further data loss.

If the server is important enough for it to be worth my time to try and fix it then it’s important enough to have these tests performed before the reboot.

• [1] http://etbe.coker.com.au/2007/07/27/a-support-guide-to-xen/

I’m just completing Jeff and Pia Waugh’s Australian Open Source Industry & Community Census [1]. There are some things that can be improved with that survey in particular and surveys in general.

It seems to be assumed that everyone is trying to work full-time. I admit that there are probably few people who have decided that they don’t need as much money as they would earn in full-time work and reduced their work hours to match their financial needs (as I have done). Surveys that just ask a for a figure of how much is earned add to the pressure to earn as much as possible, which isn’t what’s best for most people.

I have the impression that the questions about “how long have you been doing X” assume that doing so is contiguous. If that’s the case then asking “when did you first do X” and giving a drop-down list-box of the last 20 years to select from would probably be better (more precise and remove confusion).

Debian wasn’t listed as a Linux distribution! It only has Ubuntu, RHEL, Fedora, and SUSE.

The question mixing kernels and distributions was a little strange. It gives BSD as a kernel option but no BSD option in user-space, so apparently it’s assumed that there is only one user-space/distribution for BSD (there have been some attempts to release Debian with the various BSD kernels). Also it wasn’t clear what you have to do regarding the kernel to select it (is the couple of hundred lines of patches I submitted to the Linux kernel adequate to let me list it?).

There were a bunch of questions that would get very predictable answers. Do you want to have access to official government web-sites and documents with free software? I guess that they want to get a large number of people requesting such things. Incidentally much of that is in the Greens IT policy…

Immediately below the buttons on the screen to go to the Next and Previous pages there is a link to clear the form and exit. When doing something difficult like sys-admin work it’s expected that a command to wipe out your work will be immediately next to something innocuous, but for something that generally doesn’t require much concentration (such as filling out a survey) it would be good to have the dangerous options a little further away.

At the end of the survey there are questions about whether you want to be contacted about events held by various companies. I think that it would be better to have an RSS feed of such events that we can poll when we have spare time. I’m sure that the PR people running the events are happy when they see a good number of people signed up to their mailing list. But if you actually want to get people to sign up without prior contact the best thing to do is have it on a web site with an RSS feed (either a blog or a CMS) so that it can be polled, syndicated, and googled.

• [1] http://waughpartners.com.au/research/census2007″

Here is a Google Custom Search for Planet Linux Australia (homepage):

Recently my iRiver [1] H320 had some milk based drink spilt on it. I’m not sure what the drink was (I discovered it when my iRiver stopped working and the drink was dry) but it smelled like coffee or hot chocolate when I washed it off (I considered tasting it but decided that knowing exactly which drink had damaged my iRiver probably wouldn’t help me fix it).

The initial problem was that no buttons other than the play button (which is also used to turn it on) worked. When I first discovered this I had no way of hitting the reset button so my iRiver played until the battery ran flat. I tried to disassemble it by removing the five tiny phillips-head screws from the sides, but that didn’t make any part of it loose. I tried using a small amount of force on the front piece of plastic and broke two of the clips that hold it in place while getting another two loose without breaking (but there were still at least four clips to go).

Then I realised that the problem was that the keys were physically sticking and that maybe if I washed the keypad out I might get it to work. So I spent some time in a cycle of dripping water into my iRiver, pressing the buttons to get some of the nasty stuff dissolved, and then using a towel to soak up some of the water with milk or whatever. After repeating this for a while the buttons all seemed to work well apart from the play button which kept registering presses when I wasn’t touching it. This meant that it always automatically turned on and then played a song in a stuttering manner as the play button is also the pause button and it paused and played as rapidly as it could.

Finally I left it in the sun to dry for a few hours, which seemed to do some good. The play button mostly works now. Also it seems quite easy to get water between the front layer of protective plastic and the layer behind (which actually houses the keypad). So I have several large drops of water spread out between the layers which move around as I squeeze it. I think that if I get that dried out before algae can grow then everything will be fine.

• [1] http://www.iriver.com/

I recently wrote about problems with Google Earth [1]. In comments it was pointed out to me that there are some Debian packages of it in contrib. Installing the package ttf-bitstream-vera solved the font problem and running it directly (not through ssh -Y) on a machine with DRI support made it run reasonably fast on a machine with identical hardware to my mother’s.

The animation is quite slick when the hardware works, and I have used it a bit.

However I’m still disappointed in the program. The animation should be disabled for hardware that doesn’t support it at a reasonable speed (a reasonable default would be to disable animation if the display is :10.0 so that it doesn’t try to do animation over ssh). Also the feature of having movement continue should be disabled if there is any question about the performance. When performance (of scrolling and network access) is good it’s nice to be able to swipe with the mouse and have the scenery slide past until you tell it to stop. When performance is bad it’s annoying to have it keep trying to slide somewhere and make the entire machine run slowly.

• [1] http://etbe.coker.com.au/2007/09/11/google-earth-almost-a-great-program/