So Apparently I’m An Exceptionally Dull Weirdo …

 Computing, General, Media, Politics  No Responses »
Oct 252013
 

Apparently this idiot thinks that all coders are exceptionally dull weirdos. I’ll quite happily admit to being a weirdo, but as to exceptionally dull … I only seem that way to the exceptionally thick, or prejudiced.

Concentrating for the moment about this journalist’s (in the loosest possible sense of the word) insult to a good number of people, we can probably deduce the following :-

  1. He doesn’t know many developers socially. If he accidentally encounters one in a social setting one of the following occurs :-
    1. The developer denies all knowledge of computers because of the prejudice of idiots like him. This is a bit of self defence we geeks learned in the past and used in the past. So we can also assume he’s a bit of a dinosaur (like me).
    2. Once he learns someone is a developer, he will climb the walls to get out of the way.
    3. He converses in his own specialised area, and anyone who runs away is classified as an exceptionally dull weirdo.
  2. If he thinks that coding is mechanistic, he is totally clueless about programming, and thinks that anyone can simply start writing code immediately. As a little hint, the majority of the time spent programming is thinking; simply grinding out code is a relatively small part of the job.
  3. Lumping coding in with car mechanics, or plumbing in a derogatory manner indicates this guy is one of those fools who think that anything technical is a low-status activity. Hope his plumber tells him to fix it himself when his next water leak occurs, or charges him double!

Now onto the main point of his ill educated rant on the subject of teaching “coding” to school children. Hopefully the government plans to teach “programming” rather than “coding”, but does he have a point? Perhaps, although it’s a bit difficult to take an idiot like this seriously.

It really depends on exactly what and how it is being taught.

If the plan is to turn out vast swarms of fully fledged developers, everyone is going to be disappointed; apart from anything else, if we were going to turn out fully fledged developers it would have a catastrophic effect on every other subject being taught. After all, it would take so much teaching time away from other subjects, there wouldn’t be enough time for Maths, English, History, etc.

But if the intention is to teach programming in a fun way (say with Logo and robots), with the intention of giving students a better idea of how computers work and how they are instructed, it could well be a good thing.

Not everyone needs to code he claims. Actually most people may find themselves coding in ways that may not be thought of as programming – setting up formula in a spreadsheet, setting up a database, automating a task in a word processor. Although none of these are “true” programming, they do share some elements with it – not least to think about the task in hand, dividing it up into sub-tasks, and setting about telling the computer how to do those tasks in a way that the computer will understand.

Does everyone need this? Perhaps not, but they will find using computers much more effective if they have a better idea of what is going on.

What Happens When You Have 100 Partitions?

 Computing, Working Notes  No Responses »
Oct 232013
 

Crazy experiment time. What happens when you have a disk with 100 partitions? The replacement for the old MBR standard for partitions on PC hardware is slowly being replaced with GUID partitions. The later increased the maximum number of partitions to 128 which is probably far more than anyone needs, but what happens when you have a disk with 100 partitions?

As it happens, I had a spare external drive to play with, so set something up :-

for x in {1..99}     
do
  parted /dev/sdc mkpart FAT $(($x * 100)) $((x * 100 + 99))
  mkfs -t vfat /dev/sdc${x} 
done

This took a surprising amount of time to run with two interesting effects :-

  1. The mkfs tool refused to make a filesystem on /dev/sdc16 and /dev/sdc80 as it claimed it would be creating a filesystem on a full disk device. I suspect that this is a bug due to simplistic assumption of what constitutes a full disk device based on minor device numbers (/dev/sdc16 happened to be 0 and /dev/sdc80 happened to be 64). This could probably be solved by using device nodes within /dev/disk/by-${something}/${whatever}.
  2. The Unity Launcher appeared to attempt to populate itself with the new filesystems as they were being created, but very rapidly decided not to bother. This happened several times.

Once the creation process was complete, I reconnected the external drive to my Ubuntu machine, and yes the launcher does contain a ton of hard disk icons. The launcher is still full functional, but having a hundred (or so) devices below the normal icons does make using it a little clumsy.

Fortunately it did not mount all the filesystems automatically – closing that many windows would be very tedious. Mounting them all via a file manager window was pretty tedious, but it worked :-

/dev/sdc56             95M     0   95M   0% /media/mike/8663-39C5
/dev/sdc65             95M     0   95M   0% /media/mike/8673-0919
/dev/sdc71             95M     0   95M   0% /media/mike/873E-FEE7
/dev/sdc72             95M     0   95M   0% /media/mike/8741-47B3
/dev/sdc79             95M     0   95M   0% /media/mike/874D-4B53
/dev/sdc81             95M     0   95M   0% /media/mike/874E-D280
/dev/sdc82             95M     0   95M   0% /media/mike/8752-1ACE
/dev/sdc83             95M     0   95M   0% /media/mike/8754-2562
/dev/sdc84             95M     0   95M   0% /media/mike/8755-D262
/dev/sdc86             95M     0   95M   0% /media/mike/8759-0D82
/dev/sdc87             95M     0   95M   0% /media/mike/875A-E5C5
/dev/sdc89             95M     0   95M   0% /media/mike/875E-035B
/dev/sdc92             95M     0   95M   0% /media/mike/8763-8FB5
/dev/sdc93             95M     0   95M   0% /media/mike/8765-7A2F
/dev/sdc94             95M     0   95M   0% /media/mike/8767-1DBC
/dev/sdc95             95M     0   95M   0% /media/mike/8768-D314
/dev/sdc96             95M     0   95M   0% /media/mike/876A-A46E
/dev/sdc97             95M     0   95M   0% /media/mike/876B-F064
/dev/sdc98             95M     0   95M   0% /media/mike/876D-9D90
/dev/sdc58             95M     0   95M   0% /media/mike/8666-B9AA
/dev/sdc61             94M     0   94M   0% /media/mike/866B-8EFA
/dev/sdc62             95M     0   95M   0% /media/mike/866D-1726
/dev/sdc64             95M     0   95M   0% /media/mike/8671-5EE1
/dev/sdc66             95M     0   95M   0% /media/mike/8736-C2F5
/dev/sdc67             95M     0   95M   0% /media/mike/8737-EE95
/dev/sdc68             95M     0   95M   0% /media/mike/8739-7213
/dev/sdc69             94M     0   94M   0% /media/mike/873B-181F
/dev/sdc70             95M     0   95M   0% /media/mike/873C-E80C
/dev/sdc73             95M     0   95M   0% /media/mike/8743-11E7
/dev/sdc74             95M     0   95M   0% /media/mike/8745-28A8
/dev/sdc75             95M     0   95M   0% /media/mike/8746-CA94
/dev/sdc77             95M     0   95M   0% /media/mike/874A-1D30
/dev/sdc78             95M     0   95M   0% /media/mike/874B-C1C7
/dev/sdc85             95M     0   95M   0% /media/mike/8757-77A0
/dev/sdc88             94M     0   94M   0% /media/mike/875C-6DF9
/dev/sdc90             95M     0   95M   0% /media/mike/8760-8FD5
/dev/sdc91             94M     0   94M   0% /media/mike/8762-01DA
/dev/sdc99             94M     0   94M   0% /media/mike/8770-0F74
/dev/sdc1              93M     0   93M   0% /media/mike/8609-229A
/dev/sdc17             95M     0   95M   0% /media/mike/8621-921D
/dev/sdc21             95M     0   95M   0% /media/mike/8628-8CDB
/dev/sdc22             95M     0   95M   0% /media/mike/862A-2217
/dev/sdc23             94M     0   94M   0% /media/mike/862B-8EF9
/dev/sdc25             95M     0   95M   0% /media/mike/862F-0BE5
/dev/sdc27             95M     0   95M   0% /media/mike/8633-1F9D
/dev/sdc28             95M     0   95M   0% /media/mike/8634-A26F
/dev/sdc34             95M     0   95M   0% /media/mike/863E-14EB
/dev/sdc37             95M     0   95M   0% /media/mike/8643-1F63
/dev/sdc4              95M     0   95M   0% /media/mike/860D-2753
/dev/sdc40             95M     0   95M   0% /media/mike/8647-8E49
/dev/sdc41             95M     0   95M   0% /media/mike/8649-033D
/dev/sdc42             94M     0   94M   0% /media/mike/864A-A12A
/dev/sdc43             95M     0   95M   0% /media/mike/864C-6EEF
/dev/sdc44             95M     0   95M   0% /media/mike/864E-3469
/dev/sdc45             95M     0   95M   0% /media/mike/8650-8796
/dev/sdc46             95M     0   95M   0% /media/mike/8652-64DF
/dev/sdc47             95M     0   95M   0% /media/mike/8653-F743
/dev/sdc48             95M     0   95M   0% /media/mike/8655-B14B
/dev/sdc49             95M     0   95M   0% /media/mike/8657-34FF
/dev/sdc5              95M     0   95M   0% /media/mike/860E-EBD7
/dev/sdc50             94M     0   94M   0% /media/mike/8658-A04A
/dev/sdc51             95M     0   95M   0% /media/mike/865A-D4D3
/dev/sdc52             95M     0   95M   0% /media/mike/865C-33D1
/dev/sdc53             95M     0   95M   0% /media/mike/865D-FA56
/dev/sdc54             95M     0   95M   0% /media/mike/8660-6C95
/dev/sdc55             95M     0   95M   0% /media/mike/8661-D456
/dev/sdc57             95M     0   95M   0% /media/mike/8665-0AFD
/dev/sdc59             95M     0   95M   0% /media/mike/8668-3D53
/dev/sdc6              95M     0   95M   0% /media/mike/8610-F9B0
/dev/sdc60             95M     0   95M   0% /media/mike/866A-0A0E
/dev/sdc63             95M     0   95M   0% /media/mike/866E-F6E7
/dev/sdc76             95M     0   95M   0% /media/mike/8748-8D02
/dev/sdc10             95M     0   95M   0% /media/mike/8616-B29F
/dev/sdc11             95M     0   95M   0% /media/mike/8618-6462
/dev/sdc12             94M     0   94M   0% /media/mike/861A-5208
/dev/sdc13             95M     0   95M   0% /media/mike/861B-BA6E
/dev/sdc14             95M     0   95M   0% /media/mike/861D-5133
/dev/sdc15             95M     0   95M   0% /media/mike/861E-C384
/dev/sdc18             95M     0   95M   0% /media/mike/8623-BFCF
/dev/sdc19             95M     0   95M   0% /media/mike/8625-9D85
/dev/sdc2              95M     0   95M   0% /media/mike/860A-504E
/dev/sdc20             94M     0   94M   0% /media/mike/8627-1391
/dev/sdc24             95M     0   95M   0% /media/mike/862D-457F
/dev/sdc26             95M     0   95M   0% /media/mike/8631-5F8A
/dev/sdc29             95M     0   95M   0% /media/mike/8636-2F58
/dev/sdc3              95M     0   95M   0% /media/mike/860B-8C77
/dev/sdc30             95M     0   95M   0% /media/mike/8637-F726
/dev/sdc31             94M     0   94M   0% /media/mike/8639-6B19
/dev/sdc32             95M     0   95M   0% /media/mike/863A-FBBC
/dev/sdc33             95M     0   95M   0% /media/mike/863C-AE68
/dev/sdc35             95M     0   95M   0% /media/mike/8640-3A10
/dev/sdc36             95M     0   95M   0% /media/mike/8641-93A6
/dev/sdc38             95M     0   95M   0% /media/mike/8644-AFCF
/dev/sdc39             94M     0   94M   0% /media/mike/8646-1BAE
/dev/sdc7              95M     0   95M   0% /media/mike/8612-54E8
/dev/sdc8              95M     0   95M   0% /media/mike/8613-C38C
/dev/sdc9              95M     0   95M   0% /media/mike/8615-3522

Yes I have cut the “interesting” filesystems out of that output.

Windows (7) does deal quite so well with the situation. After rebooting into Windows with the disk plugged in, the login process seemed to take longer than usual (although I don’t boot Windows enough to be sure).

Once logged in, everything seemed fine including the little popup window by the status bar saying it was configuring the plugged in disk drive. However that took longer than expected – after clicking on it for details, it took around 5 minutes to complete. At which point it stuck a red cross by the “Disk Drive” whilst it popped up an Autoplay window for drives E: through Z:. With an offer to format drive T: – so it could at least use the drive that Linux refused (by default) to format.

However except for that little red cross, there was no clear warning that it failed to do anything with nearly 80 partitions. And closing all those popup Autoplay windows was pretty tedious.

OSX (10.9) dealt a little better with the disk; it at least recognised all of the disks, and stuck up little icons for each one. And mounted them all.  However Finder didn’t seem to respond to attempts to unmount the disks … I had to resort to the command-line. Perhaps I wasn’t patient enough.

And the moral of this little crazy experiment? Whilst we can perhaps throw a little mud at Microsoft, the main lesson learnt is that you too can annoy someone using Windows by handing them an external hard disk with 100 partitions. Especially if the information they want is not in the first 20-odd partitions <Evil Grin>

Oh! And just stating the obvious – it’s a good idea to remove the partitions before putting the spare disk away, or you may encounter a nasty surprise later!

 

Is The US Government Still Lurching Around Like A Drunken Sailor?

 Politics  No Responses »
Oct 172013
 

With apologies to all drunken sailors who will no doubt resent – quite reasonably – being compared with a dysfunctional government.

The big news today (and yesterday – different time zones confuse these things) is that the US government has grasped just a bit of sanity and has stepped back from the abyss. Well most of them did, but the lunatic fringe of the Republican party (also known as the Tea Party) still persisted in trying to block the government from doing any work and paying any debts it owes.

But it is only temporary, and unless some more sanity returns to US politicians, we will get to see this mess repeated in January.

Ultimately this is all the fault of a fanatic wing of the Republican party who believe it is their right to undemocratically block the government budget until their favourite hobby horse is taken care of. Obamacare. Whether it is a good or a bad thing, it is a done deal, and it is undemocratic to try to sabotage it without first giving it a chance.

Yes the US has too much public debt, but too much is made of the so-call US ‘debt crisis’. The overall figure is immense to be true – so big that it is impossible to understand; so big that we have clever means to make it understandable, and to understand it in terms of affordability. If you look at the US debt as a proportion of GDP (in other words how affordable it is), you will see that the US is in 35th position (according to CIA figures) with a figure of 73.6% of GDP. Or 9th position (using the IMF figures).

Not a good position certainly, but hardly a basket case.

Now there’s a great deal of sense in reducing US government debt, but not in this way. Simply by stopping US government cheques would cause a catastrophic effect on the US (and world) economies.

Perhaps those with a vote in the US would like to remember this when it comes to voting next time. Your current set of politicians look dangerously dysfunctional; even in comparison to politicians in other countries.

Creating and Using The Linux zRAM Feature

 Computing, Linux, Working Notes  No Responses »
Oct 132013
 

I discovered this cool feature of Linux quite by accident. zRAM is a block device (i.e. a “disk”) where the contents are compressed and stored in memory, which makes it sound rather mundane and hardly very interesting. However in use, it does appear to be quite nifty; sufficiently so that Google are enabling it for Chrome OS. So why?

The way that it is usually configured is as a swap space … so in effect, zRAM is used to compress normal memory, trading processor utilisation for more memory. What should happen is that instead of hitting the performance brick wall of suddenly paging to disk when you hit the memory limits of your machine, the zRAM is used instead eating a bit of processor time but with any luck keeping everything within memory rather than going to disk. It should have no effect during normal operation, but during temporary surges of memory utilisation, it should allow things to proceed at more or less normal performance.

That’s the theory anyway; but if it were not the case would Google be enabling it by default?

Of course in addition to using it as a swap device, there are other possible uses for zRAM devices :-

  1. As an L2ARC cache device for those using ZFS.
  2. To use as a block device for very hot disk spots in examples such as Exim’s retry database – which can be safely discarded on reboot.
  3. Or any other cache whose contents can be safely discarded at any point.

The last point is worth remembering. Because zRAM devices are contained within main memory, their contents are discarded when the power goes away.

Configuration

To use zRAM, we need to load the zRAM module, and choose how many devices to make at the same time. Some people believe that it makes sense to create as many devices as you have cores, as that gives each core (or thread) a device to spend it’s time compressing. To do this, we add the following to the /etc/rc.local file (assuming a Debian system) :-

/sbin/modprobe zram zram_num_devices=$(cat /proc/cpuinfo | grep processor | wc -l)

By default the zRAM will allocate 25% of the main memory to all of the zRAM devices; personally I think that is reasonable enough. However it seems that as soon as you set the number of devices, the size defaults to zero … so we have to set the size of the device as we configure it. Once created, you will have to decide how to use the devices. In my case, I wanted to use half of the devices for swap and half for L2ARC, which I did by adding the following to /etc/rc.local :-

size=$(( ($(cat /proc/meminfo | awk '/^MemTotal/ {print $2}')*1024) / (4 * $(cat /proc/cpuinfo| grep "^processor" | wc -l)) ))
#       Complex way of determining the size of each zRAM device
for dev in /dev/zram*
do
  base=$(basename $dev)
  echo $size > /sys/block/${base}/disksize
  odd=$(( $(echo $dev | sed -e "s/^.*zram//") % 2 ))
  if [ $odd = 0 ]
  then
    /sbin/mkswap $dev
    /sbin/swapon -p 32767 $dev
  else
    zpool remove pool0 $dev > /dev/null 2>&1
    zpool add pool0 cache $dev
  fi
done

This is a rather complex way of doing it, and doesn’t contain much in the way of error checking, but it does work.

A Growlery?

 General  No Responses »
Oct 122013
 

Sometimes people get amused when they see my blog’s tag line (“Grumbles from the Growlery”), because they get the word “growlery” confused with the word “growler”. Just to show this isn’t that sort of blog, I’m going to define it.

It’s a room for growling in; nothing more and nothing less. See “Bleak House” by Charles Dickins which has: “This, you must know, is the growlery. When I am out of humour, I come and growl here.”.

Other definitions come from :-

  1. The Collins dictionary: “a place to retreat to, alone, when ill-humoured”.
  2. The Phrontistery list of unusual words (you have to scroll down): “a retreat for times of ill humour”.

And you can probably find many other definitions yourself.

The Growlery

The Growlery

 

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