Internet

24th June
2008
written by simplelight

I was at a conference this morning where Spansion and Virident were presenting their latest flash memory technology designed to replace DRAM in web servers. Some interesting facts:

  1. Cooling and power distribution losses account for 50% of the electricity consumed in US datacenters.
  2. Datacenter power use doubled from 2000 to 2005 and will almost double again by 2010. Growth in electricity use has been slowed somewhat by the advent of server virtualization over the last few years.
  3. US datacenters use more electricity than countries like Sweden and Iran
  4. Datacenters use almost 100 billion kilowatt hours each year at approximately $0.10 per kilowatt hour. Datacenter electricity consumption is growing at 15% per year (!)
  5. Datacenter memory (DRAM) uses 2x more electricity than the total capacity of US solar panel installations.
  6. US, EU and Japan use 3/4 of the world’s electricity.

It will be interesting to see whether Spansion’s newly announced EcoRAM can put a dent in these problems. They are citing some impressive numbers:

  1. 1/5th the power of DRAM at comparable read performance.
  2. 800x faster than NAND flash access times.
  3. 30 mins to write 1TB of data on EcoRAM vs 5 hours using traditional NOR DIMM’s.

On the other hand, the representatives from Intel and AMD certainly weren’t giving their unqualified support to EcoRAM.

20th June
2008
written by simplelight

Wired has an excellent article on an optimal memorization algorithm developed by Piotr Wozniak. The technique has been embodied in a software program called SuperMemo and an open-source alternative called Mnemosyne

I’m somewhat skeptical that spending more time on memorizing facts is that useful but given that a few months ago I could barely remember the equation for the roots of a quadratic perhaps I should be more open-minded.

The algorithm is straightforward:

  1. Split the knowledge into smallest possible items.
  2. With all items associate an E-Factor equal to 2.5.
  3. Repeat items using the following intervals:
    I(1):=1
    I(2):=6
    for n>2: I(n):=I(n-1)*EF
    where:
    I(n) – inter-repetition interval after the n-th repetition (in days),
    EF – E-Factor of a given item
    If interval is a fraction, round it up to the nearest integer.
  4. After each repetition assess the quality of repetition response in 0-5 grade scale:
    5 – perfect response
    4 – correct response after a hesitation
    3 – correct response recalled with serious difficulty
    2 – incorrect response; where the correct one seemed easy to recall
    1 – incorrect response; the correct one remembered
    0 – complete blackout.
  5. After each repetition modify the E-Factor of the recently repeated item according to the formula:
    EF’:=EF+(0.1-(5-q)*(0.08+(5-q)*0.02))
    where:
    EF’ – new value of the E-Factor,
    EF – old value of the E-Factor,
    q – quality of the response in the 0-5 grade scale.
    If EF is less than 1.3 then let EF be 1.3.
  6. If the quality response was lower than 3 then start repetitions for the item from the beginning without changing the E-Factor (i.e. use intervals I(1), I(2) etc. as if the item was memorized anew).
  7. After each repetition session of a given day repeat again all items that scored below four in the quality assessment. Continue the repetitions until all of these items score at least four.

There is a website called Memverse which has implemented this algorithm for memorizing popular bible verses. I’ve been using the site for about 3 months now and it is very impressive how much you can retain using the algorithm.

18th June
2008
written by simplelight

Skype has released version 4.0 (beta) and seem to have completely lost the plot on GUI design. In prior versions it was possible to have one’s contact list docked on the right side of the screen leaving plenty of real estate for working. The new layout now takes half of a 21″ monitor and can’t be made any smaller! That now makes it impossible to keep Skype open and periodically monitor online contacts. I would be ok with Skype taking over my screen once a call has started. Before that time, though, it should remain as unobtrusive as possible while still allowing me to monitor my contact list.

Skype needs to realize that our PC’s are not phones. Communication is a means; not an end.

I would recommend staying with Skype 3.8 until this issue is resolved.

18th June
2008
written by simplelight

I have been using SmugMug for hosting my photos for a while now. There are a few benefits that make it worth the small annual subscription and don’t seem to be available from any of the free offerings:

  1. Your friends and family can download photos in full resolution
  2. Absolutely zero ads. Not having ads posted alongside your photos makes them look a LOT better.
  3. Unlimited storage and quick/easy bulk uploads
  4. A personalized URL
  5. Backups in 3 states.
  6. No need to login to view the photos (strangers really aren’t interested in your photos!)
  7. More professional look and feel. This is a website that is used by many pros.

I’ve used SmugMug for three years now and have been extremely happy with all aspects of the service. If you’d like to save $5 on a subscription, enter the following coupon in the ‘Referred by’ field:  LQvt6m1M08vGw

27th May
2008
written by simplelight

Over Memorial Day weekend I migrated my Rails Application to Dreamhost using mod_rails (Passenger). It was not an entirely smooth process but I was also upgrading from Rails 1.8.x at the same time. That was compounded by making the foolish mistake of trying to rebuild my database using Rake migrations. (That’s a bad idea. I could have saved many hours by just uploading the schema)

Here is the procedure I followed (hat tip to Nock):

  1. cd ~/
  2. rails your_app_name -d mysql
  3. Copy app/, database.yml, routes.rb, db/
  4. Change public/.htaccess from .cgi to .fcgi
  5. put your app into production mode (uncomment line 5 in environment.rb)
  6. run rake db:migrate RAILS_ENV=production
  7. chmod -R 755 ~/your_app_name/app
  8. rm your_app_name/public/index.html
  9. killall -USR1 dispatch.fcgi
  10. killall -USR1 ruby

One comment on step 4. For some reason none of my stylesheets would load. Much of the advice gleaned from endless Google searches seemed to suggest that the problem would be fixed by setting the RewriteBase in /public/.htaccess. That turned out to not be the case.

My stylesheet problem was caused by having this line twice in my .htaccess file

RewriteRule ^(.*)$ dispatch.fcgi[QSA,L]

DO NOT uncomment the one before RewriteEngine On , as all the tutorials seem to imply, just change the .cgi to .fcgi in the block below it.

Thanks to Dreamhost for their stellar support over a frustrating (for me!) Memorial Day weekend. In the end, (as is so often the case), very little of the frustration was caused by Dreamhost or mod_rails but, rather, by some of the vagaries of Rails. I’m guessing that future deployments would be much smoother as this was my first time deploying to a shared hosting environment.

26th May
2008
written by simplelight

I use Dreamhost to host my websites and they have now added support for Passenger (a.k.a mod_rails). Ruby on Rails deployment hassles should be a distant memory soon!

If you’re looking for a cheap and cheerful hosting company for your Rails app, I highly recommend Dreamhost. It’s great for the solo developer (or small team) because for a small amount per year you can launch your site on a shared hosting service and then later easily migrate it to a virtual private server as your needs change. 

Dream in Rails

25th May
2008
written by simplelight

To link to Amazon, use the following code

http://www.amazon.com/exec/obidos/ASIN/<10 digit ASIN number>/simplelight-20

Simply insert the relevant ASIN number for the product that you are linking to. You can find the ASIN number at Amazon’s Associate page

For example, to you would link to For One More Day by Mitch Albom like this:

21st October
2006
written by simplelight

The internet continues to exhibit an untrammeled elimination of the middleman. A new company, Prosper.com, now allows direct person-to-person lending. I have set up standing orders (one of the best features of the site as it allows automatic bidding on the loan requests) and have created a loan portfolio with an even risk distribution. People submitting loan requests are graded with a risk rating from AA all the way down to HR (high risk) and NC (no credit rating). The risk ratings are based on the credit scores obtained from the credit agencies.

As of writing, Prosper has 90,000 members and has originated over $18 million in loans.

It appears that there is currently a far greater demand for loans than there is a supply of capital bidding on each loan. The implications for my risk-adjusted return are not yet clear, but I think it’s a great idea. 

17th August
2006
written by simplelight

I love Skype and I’ve tracked the growth in online users since October 2003. I’ve noticed a disturbing trend the last few months. The number of concurrent online users peaked at around 6.5M users in May 2006. This peak usually occurs around 7am (Pacific Time). June and July had similar peaks but since then I have rarely seen numbers over 6.3M online users and never greater than the previous maximum. Is this caused by more people being on vacation during the summer? The next few months should answer that question.

Skype Users Online Concurrently

Increase/Decrease in Peak Skype Users Online

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