Month: April 2020

Jonas Salk Middle School Career Day

A presentation about information technology with demonstrations.

I volunteered to create a presentation for career day at school. Actually, my daughter asked me and I said “okay”. Then career day presentations were changed from in person to online because of corona virus.

It would have been so much easier for me to do in person. I’m certain the total time spent would be less than what I needed to produce the video! Everything I wanted to present could have been done live. Timing would be easier and adjustments could be made in each session depending the interest of the previous audience and questions during the presentation.

That wasn’t to be.

The good thing about the video is I was able to produce it. The bad things are obvious in review. There are several parts where the dialog is disjointed and not flowing with events on the screen. Arrangement of some screen elements blocks others in an undesirable way. And I need to think more of the audience. This is likely much better for high school seniors than eighth graders. Work more on the script and be EXPRESSIVE!

Making this video was an enjoyable and challenging experience. I had to learn things I’d never known to make the video. And watching myself and the content I can see how it could easily be improved. Information I’ll tuck away to use if and when there’s a next time.

If you’d like to check out the video, here it is.

At the end of the video is a list of the software used to produce it. That same list, with working links, is below.

Ubuntu 18.08 runs the laptop used to create this video (it’s an alternative to Windows, OS X, and Chrome OS). https://ubuntu.com/

OpenShot video editor was used to create the video. https://www.openshot.org/

vokoscreen made the screen video captures that got edited in OpenShot. https://linuxecke.volkoh.de/vokoscreen/vokoscreen.html

GIMP, GNU Image Manipulation Program, was used to create or edit some of the images in the video and to obscure and alter some portions of the video images. https://www.gimp.org/

Cheese was used to record my head shot and voice.
https://wiki.gnome.org/Apps/Cheese

Pick and OpenShot’s chroma key effect were used make the background behind my head transparent rather than appear in a box that blocked the background. https://www.kryogenix.org/code/pick/

I used LibreOffice Writer to take notes and make plans as I developed the video and for the scripts I used to guide narration. LibreOffice Calc helped calculating how to adjust length of some clips to fit the target time. https://www.libreoffice.org/

MySQL backup and restore

Dig in and do it, and repeat. Get the desired result faster by combining research and testing.

Maintenance is important. A car needs oil changes or eventually the engine will be damaged by regular operation. A server needs software updates to fix bugs and protect against threats. Even when those things are done failures can happen that create problems returning to normal operation.

For a car there needs to be a spare ready to go in case of a flat. If there’s not a spare ready for use it will take longer to get the car back in operation when a flat happens. For a computer, programs and data need to be backed up. If a disk drive crashes the information stored there may be lost or too expensive to recover, so just as good as lost.

This website has not been well protected for too long and I knew that needed to change. There’s a server operating system, a web server, WordPress software, and a MySQL database that all operate interdependently to make it work. As the amount of content slowly continues to grow my manual system to back everything up has become too cumbersome and is not done frequently enough to ensure minimal to no loss of data.

That needed to change.

Step one – automate the MySQL backups. Documentation states the “logical” backup method is slow and not recommend for large databases. The alternative “physical” backup entails stopping the database server and copying the files. The licensed MySQL Enterprise Backup performs physical backups and from what I’m able to tell runs clone databases so one can be stopped and the files backed up while the clone continues to run and is available for use.

This is a hobby operation and has limited resources so purchasing a license for Enterprise Backup is out of the question. Taking the whole thing offline to backup probably doesn’t bother anyone except me. Still, I did want to be able to continue to run the server while the databases are being backed up. Enter logical backup.

It didn’t take long to find the command, mysqldump. Confirming that it would backup everything including user names and passwords so all the accounts got restored with all the data took longer.

Despite my best search-fu I was unable to find any documentation that explicitly says “do this” to back up user accounts in addition to system databases and other databases. Let me fill that gap by saying “do this to back up user accounts, system databases, and other databases”. mysqldump -u root -p -h server.yourdomain.org --all-databases -r backup_file.sql. I did find the preceding command as the backup command. Nothing I could find said this backs up user accounts and system databases. I tested it. It does.

With the backup done, the next step is restore. And confirming the restore works as expected. Another case of things that otherwise seem obvious not being declared in the documentation.

Restore from the command line looks like this: mysql -u root -p database < backup_file.sql. But wait, I want to restore all databases. Search-fu failed again to find any explicit instruction how to restore all databases and what database to name on the command line.

Try the command without naming a database to see if all are restored. No, that fails. Then a flash of insight. Create an empty database, name that on the command line, and try the restore again. It works!

$ mysql -u root -p
> create database scratch;
> exit
$ mysql -u root -p scratch < backup_file.sql

Did this a few times and then restored the tables. As far as I’ve been able to determine the restore is an exact replica of the backed up data.

It seems odd that important use cases, complete backup of database server and complete restore of database server aren’t clearly documented. The information is there but important nuggets are left out. The only way to be sure you’ll get what you need is to experiment until you’re able to produce the results you need.

So yes, do the research but also just do the work and inspect the results. When research doesn’t clearly answer the questions backup it up with experimentation. Do both and get a result faster.