Tinkerbin

Yet another live-test service in the vein of JSFiddle and CodePen. Edit your HTML, CSS and JavaScript and test results live in the browser.

Tinkerbin

Fixing random disk errors with Ubuntu 12.04 Precise on XenServer — In Valid Logic

Recently upgraded one of my Xen VPS servers to Ubuntu 12.04 and ran into this problem (“blkfront: barrier: empty write xvda op failed”, disk would mount read-only). Fixed by booting to a rescue image, mounting the problematic /dev/xvda1 device, and editing the /mnt/etc/fstab to add the ‘barrier=0’ option.

Fixing random disk errors with Ubuntu 12.04 Precise on XenServer — In Valid Logic

Server is back up

Tech, , , , ,

Some handful of you that see this might have tried to visit the site over the past few days and found that my server was down. On Friday, Oct 12, I attempted to upgrade the operating system to Ubuntu 12.04. However, after the reboot into the new system, I started seeing filesystem errors, the root disk partition would only mount read-only, and my blog was giving the “white screen of death”. I spent what time I could trying to investigate and fix it, but wasn’t able to make headway with it at the time.

Unfortunately, I had a pretty busy schedule over the weekend, and wasn’t able to work on it again until Monday morning. However, one of my searches, based on error messages from my boot logs, turned up some information about incompatibilities between Ubuntu 12.04 and some versions of the Xen DOM (my VPS host uses Xen virtualization). There was a work-around available, which I was able to implement, and (as you can see) the server is back up and running again.

Sorry about the inconvenience!

 

 

Learnable Programming

Bret Victor, who wrote the piece that inspired Khan Academy CS, writes a beautiful piece on why KACS is not what he had in mind, and illustrates in detail what he really envisions.

It’s a great dissection of what an environment for learning programming *could* be. I like that he stresses that “programming is a way of thinking, not a rote skill”. I have seen so many examples of the latter — kids straight out of college who can write some code, but who don’t seem to have that “intuition” for how the code could be written better.

I wonder if there is some way anyone could do an analysis of programmers with “book learning” vs self-taught programmers who learned by exploration?

Learnable Programming