Bog Roll ::

It's Not Magic, It's Work!

29 Jan 2011

Making a Virtual Machine's Filesystem Larger

We have a remote server at work that is running virtual machines for various web purposes. Alas when originally created the file system of the virtual machines was smaller than we needed. The physical host system has plenty of space, we just have to grow the virtual file systems.

In principle I could have grown the file systems on the server but that would have loaded the server during the working day when the customers use it, plus our corporate network is too slow to do anything significant over the public Internet.

My original plan was top stop the virtual machines for a few seconds, copy the virtual file system, restart the virtual machine then transfer the copy to a machine at work. Once I have it on a fast system with plenty of disk-space I'd then cat some zeros on to the end of the container, boot it up with a live disk and extend the filesystem over the empty space. I'd reboot it with it's own Kernel to make sure it's all okay and happy, then copy the enlarged file back up to the remote server.

I however hit some problems... Though we have a fancy network at work, in practice it's slower than the ADSL network I have at home and not only is it slow but it often hits capacity problems, dropping connections. "Plan B" was to use a test ADSL link to pull the files down, but that still left a slight outage during the working day. Even if I could get the filesystems down to a work machine, our desktop systems all run Windows and have tiny hard drives - which isn't much help. I managed to find an older desktop system and borrow a 1 TB external drive, but in the end I decided it would be easier to do at home on my home systems.

Yesterday I pulled down a development and staging virtual system as Qemu/KVM qcow2 files. On my home server I converted them to raw image files and made them larger. Using a Debian GNU/Linux live image I booted them up, expanded the ext3 filesystem and shut them down. I rebooted them with their own KVM Kernel to test that they were okay, then converted the raw image back into a qcow2 and at the moment I'm scping them back to the server.

It's sad that I couldn't really do this at work, but at least I learnt some new stuff and I know my home infrastructure is better than works. I also found out that as expected a 2 GiB file as qcow2 expands to a 4 GiB raw imaged, which I expanded to 20 GiB, compresses back to a 2 GiB qcow2 - very cool!


24 Jan 2011

Debian GNU/Linux 6.0 "Squeeze"

Very shortly Debian 6.0 will be released, this is good as it's got good stuff in it that will be a nice step up from the current version which is starting to show it's age.

Some new things have arrived such as Google Chromium-Browser and KDE4, and some things have gone such as KDE3 and Splashy. I run testing on my desktop so won't see a radical change when the new version comes out but I'll have to upgrade the various stable systems I run once I'm happy it can all be done without any pain - which is usually the case.

KDE4 is really good now I've got use to it and it's big step up from KDE3 which while good was getting long in the tooth. Most KDE3 software is now available upgraded to KDE4 but there are some notable exceptions, for example Quanta+.

Splashy has been replaced by Plymouth, except that Plymouth doesn't work on my system. Having said that Splashy has been buggy so it's not a major change really.


04 Jan 2011

Microsoft Office 2007

After the Mythmas and New Year break I returned to work to discover that my work PC has had MS Office 2007 installed on it, instead of Office 2003.

I didn't start life hating Microsoft products, once upon a time I actually liked what they did. Now I see every change as a negative. Windows and Office gets worse at every "upgrade". Office 2007 is particularly nasty, doesn't fit with the rest of XP, looks like a child's toy, seems to be as slow as hell, and uses an already abandoned file format...

Open-source software seems to change without the same pain as Microsoft. KDE4 is radically different from KDE3 but somehow I didn't mind the transition - so it's not change that I don't like...


01 Jan 2011

Light Bulbs

Yesterday we were at our local DIY store looking for light bulbs and loft-insulation. There is a bewildering list of stuff available even in a small B&Q. Annoyingly not what we wanted. We did however get some things.

Light bulbs in the UK are annoying and getting worse:

  • Most sensible fittings use a bayonet fitting such as the BA22d/BC. In the past few years there has been an influx of cheap tat from China using the alternative Edison Screw fit system. That now means you have to deal with two incompatible socket and bulb systems.
  • There are also three kinds of bulbs in use, plain old "incandescent", "halogen" incandescent and compact fluorescent ("cfl"). Most bulbs quote their energy use in Watts and not their light output in Lumen.
    • So the newer bulbs will say something like 11 W, output 75 W. Meaning 11 W in electricity and the light out put of an old style incandescent 75 W light bulb.
    • To add to the complexity, most of the new and very popular halogen bulbs use a wide range of strange fittings and are a royal pain to find. Additionally they don't quote their light output or an equivalent to incandescent!
  • LED bulbs are also available, but they are very expensive and limited in output so hardly used yet.

At long last some things are starting to change. Old inefficient incandescent bulbs are being voluntarily phased out of use. To try and avoid confusion between the remaining bulbs, they are now at long last putting the luminosity of the bulb on the boxes, so you can at last compare them and have a better understanding of what is going on!

Lamp Type Typical Wattage Lumen Per Watt Typical Lumen Expected life (days) Cost per bulb
Incandescent 60 12-15 720-900 41.7 £30.00
Halogen 50 15-25 750-1250 125 £25.00
Compact fluorescent 11 60-80 660-880 333.3 £5.50
Fluorescent Tube (strip light) 10 80-100 800-1000 416.7 £5.00
LED 5 100-125 500-625 5 years £1.50
Life time is total running time, assuming normal usage patterns.
Cost is total running cost in electricity and bulbs over 5 years.

Modern cfl bulbs are much quicker to start then older ones, but still not as instant as incandescent (old or halogen). Some of them do claim to reach a high output level very quickly and there are clear differences between bulbs.

Modern cfl bulbs are available in a variety of colours and though I do have some in the house that are slower to start none of them have funny colours that they were prone to a decade or so ago. I've not seen oddly coloured cfl bulbs in over a decade.

Modern cfl bulbs do not flicker, cheap magnetic ballasts can cause flicker but almost all modern fluorescent lamps use electronic ballasts now - which also means they reach peak light output very quickly too.

Modern cfl bulbs are now available in a wide variety of shapes, you are not stuck with the old folded "U" shaped tube design. However the straight "U" shaped design is the cheapest and most efficient.

You can even use some cfl bulbs in dimmer systems, though they do not have the same range of light output as old incandescent bulbs and they are very expensive.

Finally if you really, really don't want use use cfl (like my father) you can now get halogen incandescent bulbs that are designed as alternatives to plain incandescent bulbs and while not as efficient as cfl or LED they still give our more light and less heat than plain incandescent bulbs.

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