Rainbow Chard – Page 3 – An assortment of indigestible things

It’s always useful to get your network gear to send their logs somewhere else in case they die, reboot, or go on fire. In a domestic setting this can be very useful if you have some problems with the stability of your link. However, in the case of the X3500, Linksys’s knowledge base says

11.Does the X3500 support transmission of log information to a log server?

No, the Linksys X3500 does not support transmission of log information to a log server.

Welllll…. that’s kind of true, in that there’s no option to enable it, so I suppose it’s not supported. However, it can be done. Linksys would probably say that this will invalidate your warranty, set your hair on fire and poison the groundwater, but a big fat ‘muh’ to them.

How to get line stats out of a Linksys X3500

By Ian Chard

On 4th June 2013

In networking

My Linksys X3500 (complete with muddy paw-prints)

The Linksys X3500 is, as the manufacturer would have it, a very capable device indeed. I won’t bore you with the details because, if you’re reading this, you’ve probably already got one. If that’s the case, you’ll know that (like so much consumer networking kit) the management interface leaves a great deal to be desired: it’s buggy, slow, unreliable, and has a penchant for dropping your connection when you make changes. What’s more, Linksys hasn’t provided updated firmware for over six months, and for such a new device that’s kind of worrying. But that’s a rant for another day.

How to stop Thunderbird hammering your CPU

By Ian Chard

On 19th February 2013

In random

My mail client of choice is Thunderbird. It’s always served me well, but recently I’ve noticed that my laptop’s battery life is abysmal when it’s running. A bit of poking reveals that it’s a real CPU hog if you have large mail folders (and I never delete anything!). Finally I found this bug report which has a working solution. It makes Thunderbird 17.0.2 much more gentle on the CPU, and according to the report, should work from version 15 onwards. Perhaps they’ll fix this by default eventually, but for now here’s a quick step-by-step on how to fix the problem yourself.

Another reason to dislike my MP (as if I needed one)

By Ian Chard

On 12th February 2013

In politics, rants

This is a picture of Geoffrey Clifton-Brown, my MP. There are several reasons why I don’t like him. Firstâ€”and most obviousâ€”is that he’s a Tory, and just about the only thing I have in common with Conservatives is that we both like the colour blue. Secondly, he’s an archetypical Tory^[1]: he’s related to the 1st Viscount Ruffside, went to Eton, receives an income from properties in London and Norfolk, ‘flipped’ his second home to Gloucestershire, and of course he likes firing guns at things. Finally—and most annoyingly—I’m stuck with him. He’s been an MP continuously since 1992, and in 2010 he polled a majority of over 12,000, making him pretty much untouchable.

How to align partitions for best performance using parted

By Ian Chard

On 30th January 2013

In storage

Some nicely aligned macarons There are two common problems when creating partitions in Linux on big storage arrays. The first is easy, and the warning message from fdisk is a bit of a giveaway:

WARNING: The size of this disk is 8.0 TB (7970004230144 bytes).
DOS partition table format can not be used on drives for volumes
larger than (2199023255040 bytes) for 512-byte sectors. Use parted(1) and GUID 
partition table format (GPT).

The answer: use parted. Don’t have it? Install it!

If the Church of England wants to be sexist, it should walk away from the Lords

By Ian Chard

On 21st November 2012

In politics, religion

The Lords Spiritual remain all male

Despite blanket coverage in the quality media, most of the British population did little more than raise a puzzled eyebrow at the decision of the Church of England’s General Synod to reject proposed legislation which would have allowed for the consecration of women as bishops. The majority of the population has little contact with the church, and it’s easy to dismiss the recent news as a curious anachronism: a decision which is plainly at odds with our progressive society, but only affects the Anglican church and its members. Most religions, after all, have sexism built into their doctrines at some level.

Unfortunately, this misguided decision affects us all.

Cotswold District Council’s finances laid bare

By Ian Chard

On 29th October 2012

In politics

A couple of weeks ago (when I was supposed to be revising), I added some code to Armchair Auditor, a great bit of free software by Adrian Short. He wrote it to ingest spending data from Windsor and Maidenhead and present it to the public in a form that’s easily used for analysis and general poking around.

Recently, Cotswold District Council announced that it would start including all payments to suppliers without a lower limit (previously this limit was Â£500). My addition to Armchair Auditor allows for the processing of CDC’s spending data (with all its formatting idiosyncrasies) so that it can be presented in as useful a way.

I’m no data analyst, but perhaps there are interesting things to be found in the data. Have a look at the Cotswold District Council Armchair Auditor, and see what you can find—and please do leave a comment if anything interesting turns up!

Getting rid of automounts that won’t go away

By Ian Chard

On 22nd October 2012

In Uncategorized

If you delete an automount from a map and restart the daemon, the mountpoint should go away… but sometimes it doesn’t, and you end up with this:

drwxr-xr-x 2 root root 0 Oct 22 11:24 /wibble

The size of zero indicates that the system still sees a mountpoint here, and in /proc/mounts you’ll see something like

/etc/auto.mymap /wibble autofs rw,relatime,fd=5,pgrp=31311,timeout=86400,minproto=5,maxproto=5,direct 0 0

So the mountpoint is both there and not there, and any attempt to access it will hang. Trying to unmount it manually doesn’t work either. This can cause merry hell: on a default system, the updatedb process that locate uses will hang forever when it reaches the mountpoint (even though it’s configured to ignore nfs and autofs), and the rest of cron.daily will never be reached, so no log rotation for you. After a few days you’ll see lots of find processes cluttering up the place.

A reboot will fix it of course, but there is a much simpler and less destructive way:

umount -l /wibble

The ‘-l’ option is described in the manpage as

Lazy unmount. Detach the filesystem from the filesystem hierarchy now, and cleanup all references to the filesystem as soon as it is not busy anymore. (Requires kernel 2.4.11 or later.)

That suggests a reboot might be warranted at some point to make sure it’s completely gone away, but it certainly does the trick. The entry in /proc/mounts disappears, and the directory now looks like

drwxr-xr-x 7 root root 4096 Oct 22 11:40 /wibble

A much healthier-looking directory, which you can now safely delete. Don’t forget to kill all those backlogged jobs too.

The fragments of a short and tragic life

By Ian Chard

On 26th September 2012

In random

The story of Jewish migration in the last 150 years is amply documented. It is a seemingly endless trail of persecution, destitution, and desperate flight from home. Its legacy is written across the world, and is etched into the modern Jewish character: many older Jews will wear expensive jewellery as an instinctive hedge against the possibility that one day they might have to flee. Ultimately—at least from a popular modern perspective—it was a story with a happy ending: those that escaped worked hard and eventually built successful lives elsewhere, securing a bright future for their children. Of course this is saccharine. Like the refugees of today, many migrants remained desperate and obscure, leaving little for history to record. From the fragments that remain, I have reconstructed the life of one unremarkable man.

Did you know Don Richards?

By Ian Chard

On 22nd September 2012

In random

This grainy image is the only picture I have ever seen of my maternal grandfather David Samuel Richards, known to his friends as Don. He worked for a family in Theydon Bois in the 1930s, as an engineer at Martin-Baker during and after the war, and was also an amateur wrestler. My grandmother divorced him in 1960, shortly before destroying every piece of evidence that he ever existed. All contact was subsequently lost. This may be the only surviving image.