Petrol prices are always on the rise. I decided to do some analysis on some raw data comparing the price of Brent crude oil and the price of petrol. The details of the analysis are on my site. I found out that there is a direct correlation between the price of Brent crude oil and the price of petrol at the pump excluding duty and VAT.
A colleague asked me how much bandwidth Spotify uses. I basically had no idea. I want to run Spotify on my mobile at some point, so it got me thinking. I decided to do some basic analysis. I ran the client behind a http proxy for a day or so and ran a tcpdump at the same time with a filter to capture all the traffic to the proxy. The dump ran from 19/10/2010 11:46 to 20/10/2010 17:19 and produced a 362M capture file. For the most part I was not playing any music, then for the last few hours I played music I had not played before.
This year seems to have flown by so it’s resolutions time again. I’ve done quite well; I managed to stay relatively healthy and read loads of books but I failed completely to keep up to date with LWN.
Rsync is ace. It’s also available for Windows as part of the Cygwin distro. Every time I need it I have to do a token Cygwin install, install rsync, copy out the various rsync files and remove the Cygwin install. Here, mostly for my pleasure, is a very out of date zip with just the rsync files in!
On Sunday (03/10/2010) my laptop had a bad crash. The screen went blank; I could still see the cursor and move it around, but could do nothing else. I could not even log in on a virtual console. After I typed the user name it came straight back with a login prompt again. I rebooted, grub loaded, Linux ran, the initramfs loaded and started and then it moaned about not being able to mount the root filesystem and dropped me to a prompt.
This is a quick guide on how to configure an ODBC connection from windows to a Symantec OpsCenter Server. OpsCenter is a Symantec product that integrates various backup products including Netbackup to generate various reports and warnings about how the systems are performing. It used to be a purchasable option with NetBackup 6, however since the release of NetBackup 7 a cut down version is bundled in. It works quite well and can generate pretty reports in various forms and do various things to them. However it’s not very customisable. OpsCenter actually uses SQL Anywhere RDBMS as a back end for all the data. Thus if ODBC is configured anything can query the very same data and produce reports. I’m going to use crystal reports to generate many pretty pie charts.
OpsCenter is a Symantec product that makes reports for various backup products including Symantec NetBackup. I recently decided that I wanted to improve the reporting of our backups so looked into playing with OpsCenter. It turns out that it’s not actually that configurable, which is a shame as it’s mostly quite good.
I use Nagios for monitoring. Up to recently I used a regular modem to send sms text messages to various people when systems are going wrong. The way this works is by using smsclient which dials up to a TAP server. [TAP] (http://en.wikipedia.org/wiki/Telelocator_Alphanumeric_Protocol) is a fairly archaic way of sending messages. It’s been fairly reliable however it has two major drawbacks, sending takes a long time and it’s limited to 160 characters. As far as I can tell it will not do long text messages, which are really just multiple short message combined together in a special way.
I was looking at a development web site I am involved with and I was interested in where the site was in the big bad world, so I decided to traceroute to it [1]. What seemed very unusual was that the 5th hop reported an IP address in the 10.0.0.0/8 private address space. To quote Sam “10.what now?”. I’m still amazed that packets with private source addresses are routed across the Internet![2]
I go to spinning quite a bit and I think I have had six teachers over the last year since I started. I think every teacher has one phrase they use most; this is not a bad thing, it’s just something I have noticed. I present an anonymous list of them here.
Recently I needed to find a way to search for accounts in an active directory that are enabled and have not logged on for a while. Fortunately there is a lastLogon attribute, unfortunately this is not replicated across the various domain controllers. Lord only knows why, but lastLogon is the number of 100 nano second intervals since 1601, fortunately this is documented.
Since Christmas I have been up to loads. I went skiing in March and I went to Cuba in June. I have done well with resolutions, I managed to stay super healthy for January and managed to mostly keep to it since. However I utterly failed to read LWN :-(
It’s time for some new year’s resolutions! Hopefully if they are cast in stone (well blog) there is more of a chance of success.
I passed my amateur radio Intermediate exam, so now I can kick out 50W! My new call sign is 2E0TDS. My thanks go to all at SADARS that helped with the practical day and two days of lectures and exams. All I need now is some sort of radio!
Last week I got back from a little holiday in Dublin. I went over for my cousin’s graduation. I had an amazing time, it was a very relaxed and slow paced get away from everything. We went to all sorts of different cafes, restaurants and live music bars in the evening. It felt so luxurious to stay in a hotel in the centre of town, we were able to roll out of which ever bar we were in, hail a cab and be back home in no time. Coming back to a made bed and fresh towels can’t be beaten.
After reading depesz’s great speeding-up-dumprestore-process blog post, I started thinking about how to securely transfer a file from one server to another in the fastest possible way. The problem being that scp/sftp is slow for various reasons. ftp, http, nc, cifs, rsync are all plain text so can be quickly discounted. I don’t know if ssltunnel suffers from the same window limitations that ssh suffers from. I guess using a dedicated VPN would do the trick. However I liked the idea of using gpg. I was not sure which cipher to use so I decided to run a few benchmarks to see. The results are on my site. Once the encrypted file has been created then it can be transferred using any of the available plain text mechanisms. I think nc or ftp have the least overhead.
So today I played a bit with some big cheap disks. I have 3 fairly old desktops each with 4*1TB disks, all exported via ATA over Ethernet to a much more modern sort of disk head. Basically it’s a “build a large store on half a shoe string” project. I’ve not quite got the network side of it sorted yet. Currently the disk head’s gigabit card is being saturated. On a single disk node each disk can do about 80M read sustained. If all 4 are read at the same time it goes down to about 50M, which is 200M in total. Which seems quite amazing for a Pentium 4 3.0Ghz. Also this seems a bit high as the PCI bus can only do 133M, I’m guessing that the onboard sata ports are somehow separated from the extra pci sata card I added. Interestingly one disk node can sustain 80M read from disk to the disk head. Again this backs down to 30M if all 4 disks are read, that’s 120M total, no surprise this is saturating the gigabit link. So the major bottleneck is the disk head. Currently max raid sync speed is 10M, ie 120M total for 12 disks. Ideally 3 nics in the disk head would be best, but then there is no way for the data to get to the disk head.
AnchorFix is a Greasemonkey script that I wrote to fix anchor links. This script searches for links that have anchors and adds an anchor icon that links to that anchor. Use case: sending a URL to someone without having to scroll to the top to find an anchor link or worse reading the HTML source and hand editing the URL to add the anchor. It also searches for links that link to an anchor on the current page and signifies this by adding an anchor icon after the link text. Use case: reading a page with a menu system at the top; some links are off site and some are anchors to the current page. After reading the whole page which links are worth clicking, the anchor indicates this.
