JDPFu.com 2025

Almost every week, I see the same question asked on different technology websites. That question, "How should I learn to program X?" Below I'll attempt to provide a considered answer that question. Other people will have different answers.

In my research for the last article on USB storage and KVM clients, I came across a few articles that should improve disk performance.

I also decided to tweak some HDD performance parameters. The commands used and results are below. If you have a disk array, you probably want to tune the parameters to increase read performance. My RAID setup saw a 41% disk read improvement. That’s pretty impressive for 20 minutes of effort. If you just have single disks, the default settings seemed fine and didn’t make much difference on my machines, but for many others there are big differences. Performance tests for SATA, PATA, Laptops, USB and RAID disks were performed.

Below are links to those articles, my performance tests and scripts for different systems, and my final tuning decisions based on those tests.

After getting Windows7 Media Center running in a KVM Virtual Machine a few weeks ago, I’ve been mostly happy … except that the Recorded TV/ folder available it too small.

USB2 Storage

In an attempt to provide more room for these recordings, I created a 388MB raw disk on an external USB2 disk and attempted to add that to the virtual machine through virt-manager. At this point, I’m unsure why it doesn’t work, just that at VM startup, it fails. Removing the 2nd virtio disk from the VM and the client starts without issue.

Dennis Ritchie has died.

Mr. Ritchie was a major contributer to the invention of the UNIX operating system and the inventor of the C Programming Language on which many other programming languages are based. If you have an electronic device with firmware, it is probably programmed in C. Almost every modern operating system is also programmed in C. C is one of the most efficient and most portable computer languages available. Almost every computer has a C compiler available.

Hello World

This Hello World program was provided in the first edition of the K&R book about C in 1978.

main()
{
    printf("hello, world\n");
}

The world would be a very different place without this man. It is sad that most people have never heard his name.

It happened again to another website. Their password database was stolen. The entire DB. At least they were encrypting user passwords in some way. That will slow down the crackers, a little, but in the end, almost all those passwords will be known. My readers know that only the longest passwords will be safe, for now.

If you run a website, it can happen to you too. Can you Prevent this from happening? Probably.

My old backup method was a little cumbersome. To ensure a good backup set, I’d take down the virtual machine, mount the VM storage on the host (Xen), then perform an rdiff-backup of the entire file system, before bringing the VM back up again. This happened daily, automatically, around 3:30am. It has been working for over 3 years with very few hiccups. I’ve had to restore entire VMs and that has worked too. One day I needed to restore the Zimbra system ASAP. From the time I decided to do the restore until end-users could make use of the system was 20 minutes. That’s pretty sweet in my book.

There are some issues with the current setup.

• Backups are performed locally, to a different physical disk before being rsync’ed to the backup server. This is necessary because the backup tool versions are different and incompatible between Ubuntu 8.04 and 10.04 LTS servers.
• Each system is completely shutdown for some period of time during the backup process. It is usually 1-4 minutes, but still that is downtime.
• Most of the systems are still using 8.04 paravirtual machines under Xen. A migration of some type is needed to a newer OSes. I should use this opportunity to make things better.
• Some of the systems are running old versions of software which are not up to current patch levels. I guess this happens in all IT shops. None of that is available outside the VPN, so the risks are pretty low.

think I can do better.

This month has seen lots of behind the scenes changes here. Most will not be seen by casual visitors. Anyway, I was going through the web analytics and noticed this section concerning the different plugins that are enabled in a browser when they visit here.

78.1% Flash Support
68.8% Java support
61.8% Quicktime audio playing support
58.4% Windows Media audio playing support
49.0% PDF support
09.6% Real audio playing support
09.2% Macromedia Director Support
08.6% Javascript disabled

For the last few years, I’ve wanted to move the Windows7 media center from a physical PC onto a virtual machine.
To accomplish this, I knew that I needed a few things setup and ready to go first.

• Virtual Machine Hypervisor that was stable and efficient
• TV Tuner device that worked from inside a VM
• Storage to hold the recorded files.

I was reading an article on Lifehacker about adding fancy effects to a Linux desktop. Of course, they showed how to do it with 11.04 Ubuntu – which is unstable on my systems. Should I be without the wobbly windows? No! You shouldn’t do without either.

If you want smaller image file sizes at the same resolution, but files that still display nice. Check out the ImageMagick tool convert.

The size reductions can easily be 50% to 90% without a noticeable loss in quality.