Column Width in Blogs

July 22, 2007 | etbe

I have just been reading the LinuxWorld Community blog which seems to be mostly Don Marti’s personal blog (currently there seems to be no-one else blogging on that site).

One thing that disappointed me is that the theme designer made it look good at a width of 1000 pixels and no other size. At a smaller width the adverts on the right are cut off (more of a problem for the site owner than for the readers) and at a larger width you have a thin column of text in the middle of the screen. A quick test revealed that while my own blog looks good in wide windows it doesn’t work too well in 800 pixel width and gets very bad at lower widths – my blog would be essentially unusable at 640×480 resolution as the text column in the middle (the most important column) is the one that reduces in size. The LinuxWorld blog has a minimum size of 1000 pixels for the scaling so it allows horizontal scrolling in 640 pixel width and remains quite readable.

The top entry in a google search for web size stats is Browser News which claims that 12% of web browsers are on 800 pixel wide screens. The next link I found claims that as of January 2007 there are 26% of web users with screens that have higher than 1024×768 resolution and 14% with 800×600.

Apart from the first couple of months of blogging my blog has always looked good in screens greater than 1000 pixels wide, but not having it work at 800×600 is a problem. The first thing I did was alter the style.css file for the Blueline theme for WordPress to use 100% of the display width (not 86%). Wasting 14% of the screen width is not a good thing when using a width-intensive three-column theme. This change made my blog work well in 800 pixel width and be bearable in 640 pixel width.

The other change was to use min-width: 700px; in the style.css sections blogtitle, container, and navigation. This means that at 640 pixel width the text column will take more than 1/3 of the screen and should be quite readable (unless the reader has an unusually large font setting). The down-side to this is that if your window width is less than 700 pixels then you will have some horizontal scrolling, but I think that this is an acceptable trade-off.

I was forced to confront this issue when talking to a prospective client about the potential for blogs to be used in his business, he loaded up my blog on an ancient windows machine and it didn’t look very good at all, this coincidentally happened a few hours after I had been reading the LinuxWorld blog on a big screen.

Ron Paul

July 21, 2007 | etbe

A politician named Ron Paul is running for the Republican party nomination for president. Tech Crunch has an article about his Web 2.0 based campaign which also includes a link to a google interview with him.

Here’s the good things about him:

He strongly defends the constitution and the rule of law, so he’s not a totally bad guy (unlike many of the current politicians who believe that the US president should be able to do whatever he wishes).
He wants to refrain from “helping” other countries with their “defense” – such help from the US has caused most of the wars and terrorism around the world since WW2.
He wants to reduce military spending to 1/3 current levels (he could reduce it to 1/10 current levels and still be able to prevent a combined attack by Russia and China).
He wants to restore liberty.
He seems to be in support of repealing most drug laws – but his statements weren’t clear.

Here’s the bad:

He wants to remove income tax and give the smallest possible government – no consumer protection laws among other things.
He thinks that hospitals should be run by churches and have no government funded medical system.
He doesn’t want restrictions on pharmacists who refuse to sell certain drugs (IE the contraceptive pill) – but with no restrictions on who can be a pharmacist such things could be bought without prescription even…

Here’s the ugly:

He claims that guns on planes might have prevented 9-11.

Still, he’s a lot better than any other Republican who seems to be in the running.

unaligned access on IA64

July 21, 2007 | etbe

I recently had some problems with unaligned access on IA64, messages about unaligned access were being logged via printk and I couldn’t determine the cause – or even how to track it down. To test what an unaligned access means (which wasn’t documented anywhere that a quick google search could find) I wrote the test program in the second half of this post. Below is the output of the test program which accesses an integer at various offsets. As you can see it’s addresses that are congruent to 5, 6, and 7 mod 8 that cause the errors. At the int is 4 bytes long it seems that the cause of an unaligned access error is an access to a data type that crosses an 8 byte boundary. So a pointer or long long would have to be aligned to an 8 byte boundary, an int has to be at an address that is congruent to 4 or less mod 8, and a character can be anywhere.

Also if the sysctl /proc/sys/kernel/ignore-unaligned-usertrap is set to 1 then these messages will be disabled. But you really don’t want to do that, such errors apparently cause a significant performance loss so you want to file bug reports against programs that do this.

# ./a.out
index: 0
index: 1
a.out(10393): unaligned access to 0x607fffffff34ee25, ip=0x4000000000000961
index: 2
a.out(10393): unaligned access to 0x607fffffff34ee26, ip=0x4000000000000961
index: 3
a.out(10393): unaligned access to 0x607fffffff34ee27, ip=0x4000000000000961
index: 4
index: 5
index: 6
index: 7
index: 8
index: 9
a.out(10393): unaligned access to 0x607fffffff34ee2d, ip=0x4000000000000961
index: 10
a.out(10393): unaligned access to 0x607fffffff34ee2e, ip=0x4000000000000961
index: 11
a.out(10393): unaligned access to 0x607fffffff34ee2f, ip=0x4000000000000961
index: 12
index: 13

Below is the test program I used:
Continue reading →

HP Sponsors Computer Recycling

July 20, 2007 | etbe

Hewlet-Packard is sponsoring the recycling of old computers in Victoria, Australia in a program named Byteback – note that they accept all brands of computer and charge nothing to accept the e-waste. This is a really good thing, I’ll start saving up my old computer parts to deliver to them!

Is there a directory of computer recycling plants that accept old hardware for no charge? If you know of one in your area then please blog about it and send a track-back to my post.

Bizarre “No space left on device” error from Xen

July 20, 2007 | etbe

What should have been a routine “remove DIMMs and run memtest until things work” procedure to solve a memory error became a lot more complex due to poor error handling in Xen.

The following error occured because the tdb database /var/lib/xenstored/tdb was corrupt. To fix it you must rm the file and kill the xenstored process (which will otherwise recreate the file with the same corrupt data). It took me a few hours to work this out.

# xm create -c smtp
Using config file “/etc/xen/smtp”.
Error: (28, ‘No space left on device, while writing /local/domain/0/backend/vbd/
18/768/online : 1’)

Strangely the command “/etc/init.d/xend restart” does not restart xenstore or xenconsole (which is why running “/etc/init.d/xend stop” before rm’ing the file didn’t do any good).

After fixing the above problem I encountered the following error condition. It seems that there is no support for restarting daemons such as xenstored. So I had to reboot the machine. After that it worked.

# xm create -c smtp
Using config file “/etc/xen/smtp”.
Error: Device 0 (vif) could not be connected. Hotplug scripts not working.

I’ve filed Debian bug 433780 about this.

The ABC and the Supposed Liberal Bias

July 19, 2007 | etbe

A common meme is that the media is biased towards the political left. This meme was deliberately created to encourage well-meaning journalists to be more generous in their reporting of Neo-Cons in a misguided attempt at being fair and also as a mechanism for refuting criticism of any media reports that criticise Neo-Cons.

The ABC has been criticised for being biased towards the left as part of this attack on fair media and have recently demonstrated that they are in fact biased towards the Neo-Con ideas by airing a pseudo-documentary about climate change The Great Global Warming Swindle.

The fake documentary has been refuted by many scientists, here is one by George Monbiot published in The Age.

I wonder whether this blog post will get Google adverts related to Nostradamus and UFOs – I’m sure that the google search engine has worked out that cranks are interested in that fake-doco.

Religion and Cars

July 19, 2007 | etbe

The Catholic Church has recently issued a set of 10 road commandments. Number 9 is “On the road, protect the more vulnerable party” which ties in with an article by Barney Zwartz published in the religious column of The Age about the spiritual issues related to 4WD cars.

Barney makes better points than the Catholic Church starting with “How can Christians living in suburban Melbourne justify getting around in huge four-wheel drives? It’s harder to imagine a more “me-first, up yours” statement to the rest of the world*“. He also links to a report by the Australian Academy of science showing that 4WDs are less safe for their owners (which fits the theory of some Christians that bad actions tend to get punished in this world as well as the next).

IEA predicts global oil crisis

July 18, 2007 | etbe

The ABC reports that an oil shortage is predicted soon. The International Energy Agency predicts that oil supply problems will start within the next five years. Oil production has been dropping over the last two years (we have passed the “peak oil” point) and demand is steadily increasing. Regardless of wars oil prices will increase significantly in the near future.

According to the Australian Bureau of Statistics the average age of Australian cars was 10.7 years at the end of 1998. So the vast majority of the current fuel-hungry cars on Australian roads will still be in use in five years time – if the owners can afford them.

The government needs to start providing tax incentives for fuel efficient cars and to end tax incentives for inefficient cars. Currently 4WD vehicles have reduced taxes and the tax deduction for a business car is based on the engine size (get a less efficient car and get a bigger tax deduction).

The government claims to be protecting the economy (at the expense of the environment). But with the way things currently work the economy will be destroyed in less than five years.

Even though the government cares little for the environment (in spite of the effect that climate change is having on farmers) they need to do something if they want to fulfill their claims of protecting the economy!

Thanks to Chris Samuel for informing me of this.

Correspondent Inference Theory and the US

July 18, 2007 | etbe

Bruce Schneier writes about Correspondent Inference Theory which deals with situations when the motives of an individual or group are inferred by the results of their actions. Both his article and the MIT article on which it is based only consider the results of terrorist actions against the US and allied countries.

I believe that this is a serious mistake by Bruce, the MIT people, and most people who write about terrorism. The most sensible writing about Terrorism is by Noam Chomsky. Noam considers the definition of Terrorism in both propaganda and literally. By the literal definition of terrorism the US government is responsible for more than it’s fair share of terrorist acts performed around the world.

There is no reason to believe that people in the Middle-East are any less intelligent than people in the US and Europe. It seems obvious that some of the people who’s countries are destroyed by violence sponsored by the US government will believe that the US is entirely inhabited by blood-thirsty monsters. The number of US citizens who realise what their government does and approve is very low as is the number of Muslims who know what Al Quaeda does and approve of it.

The US government claims that it wants democracy in the Middle-East, and Osama bin Laden claims to want the US military out of the Middle-East. If the US forces were withdrawn from Saudi Arabia then it would probably lead to a significant increase in democracy in the region (it couldn’t get any less democratic) – both sides could get what they claim to want.

The discussion of the MIT paper seems to be largely based on the fact that Correspondent Inference causes the US government (and other governments) to decrease the probability of doing anything that might meet the terrorist goals. But no-one has mentioned the possibility that the same may apply to the probability of non-state organisations doing anything that might meet the goals of the US government. The wars in Iraq and Iran have significantly decreased the capabilities of the US military, they can’t recruit enough new soldiers and the current soldiers have reduced effectiveness due to long tours of duty with short breaks. The US economy is stagnating partly due to the direct effects of financing the wars, partly due to the way the airline security theatre has hurt trade and tourism, and partly because everyone has been concentrating on other things instead of fixing the economy.

When two states have a war there is always the possibility of it being ended by a peace treaty or one side surrendering. With modern communications fighting can end in a matter of hours after a cease-fire has been arranged between states. But when non-state forces are involved things become much more difficult to manage. A state can make a deal with one non-state group only to discover that another non-state group (or a dissident faction within the original group) doesn’t like the treaty and continues fighting. With non-state terrorist acts connected to Al Quaeda in the US, the UK, Spain, and Indonesia (and more acts apparently planned in other countries) it’s obvious that we aren’t going to get a clean or quick solution to this problem.

It seems to me that the only way the US and allied countries can escape from Correspondent Inference is to withdraw from the Middle-East entirely. If the people of Iran or Palestine want to elect a government that you don’t like then let it go (that’s what democracy is about anyway). If a dictator seizes control of Iraq then either leave him in control or provide air-support to any province that wants to rebel and establish a democratic government. Either make a stand on the principle of support for freedom and democracy or do nothing on the principle of letting people in other countries sort out their own problems. An invasion for the wrong reasons might fool people on the other side of the world but is unlikely to fool many people who live in the target country.

Testing STONITH

July 17, 2007 | etbe

One problem that I have had in configuring Heartbeat clusters is in performing a STONITH that originates outside the Heartbeat system.

STONITH was designed for the Heartbeat system to know when a node is not operating correctly (this can either be determined by the node itself or by other nodes in the network) and then force a hardware reset so that the non-functional node will not interfere with another node that is designated to take over the service.

However sometimes code that is called by Heartbeat will have more information about the state of the system than Heartbeat can access. For example if I have a service that accesses a filesystem on an external RAID then it’s common for the RAID to track who is accessing it. In some situations the RAID hardware has the ability to “fence” the access (so that when machine B mounts the filesystem machine A can no longer access it). In other situations the RAID may only be capable of informing the system that another machine is registered as the owner of the device. To solve this problem a machine that is to mount such a device must either prohibit the previous owner from accessing the device (which may be impossible or unreasonably difficult) or reset the previous owner.

Until recently I had been doing this by writing some code to extract the STONITH configuration from the CIB and call the stonith utility. The problem with this is that there is no requirement that every node be capable of performing a STONITH on every other node, and that even if every node is are designed to be capable of rebooting every other node a partial failure condition may restrict the set of nodes that are capable of performing a STONITH on the target.

Currently the recommended way of doing this is via the test program. Below is an example of the command used to reset the node node-1 with a timeout of 20000ms and the result of it being successfully completed. I have suggested that the Heartbeat developers make an official interface for doing this (rather than a test of the API) and I believe that this is being considered. In the mean time the following is the only way of doing it:

# /usr/lib/heartbeat/stonithdtest/apitest 1 node-1 20000 0
optype=1, node_name=node-1, result=0, node_list=node-0

etbe – Russell Coker

Linux, politics, and other interesting things