Tuesday, March 11, 2008

The silent MP3: To bed with the iPod Shuffle or Zen Stone

Flaws in products call for hacks, so that's why I tried to solve the following annoyingness.

Lots of people listen to their mp3 player in bed and fall asleep with the music still on. "Shuffle" players like the iPod Shuffle and Zen Stone don't have a "do not repeat" option, so they just continue playing songs until the battery dies. That will most probably disturb your good night's rest, and apart from that you will wake up with an empty battery. And we don't want either of these, do we.

I figured that a small hack could solve both problems: put a very long silent MP3 in your playlist. You could peacefully sleep over it and it wouldn't drain your player's power either. So I generated a set of MP3 files that occupy just 3.5 MBytes per hour of true quality silence. They are encoded at 8 bits, mono and 8 KHz (the minimum sound quality playable by most players). The links are at the bottom of this post, packed as .rar archives. This is how it works:
  1. Determine how long you want to sleep, e.g. 7 hours.
  2. Download the corresponding silent mp3 file and put it in your playlist just after the track by which you will likely fall asleep. If you don't have a playlist, simply rename the mp3 so that it is played after the last music track you want.
  3. Go to bed with your favorite music, fall asleep and enjoy the silence.
  4. Get up, switch off your mp3 player, and have a croissant.
Suggestions are open for other uses of these silent MP3s. So onto the next problem now: avoiding being strangled by the headphone chord while sleeping.

Files (compressed with RAR):
Update 16th April 2009: Due to popular demand I'm adding a complementary set of shorter MP3s, for all you sleephackers out there. This should cover your napping needs.

Monday, February 18, 2008

Hosting Uptime/Downtime Calculation

While searching for hosting companies for a number of websites I'm working on, I noticed that a lot companies in Spain try to sell 99.5% guaranteed uptime as being very little downtime. Since this seemed like less than the average to me, I figured I might do a little calculation.

guaranteed uptime max downtime downtime / week downtime / month downtime / year
99% 1% 1.68 hours 7.2 hours 3.65 days
99.5% 0.5% 50.4 minutes 3.6 hours 1.825 days
99.9% 0.1% 10.08 minutes 43.2 minutes 8.76 hours
99.99% 0.01% 1.008 minutes 4.32 minutes 52.56 minutes
99.999% 0.001% 6.048 seconds 25.92 seconds 5.256 minutes
99.9999% 0.0001% 0.6048 seconds 2.592 seconds 31.536 seconds
99.99999% 0.00001% 0.06048 seconds 0.2592 seconds 3.1536 seconds

While most of these scenarios are not really realistic, it is interesting to see what companies are really offering. Reading about the recent Amazon S3 outage makes one want to place things into context. Amazon's goal is to offer 99.9% uptime, which means a maximum of 0.1% downtime and therefore not more than 43.2 minutes of downtime per month. The outage took little more than 2 hours which qualifies it as a 99.5% host this month. That's a long way from the 99.999% they should be offering for cloud computing indeed.