I’ve released a small perl script named wwaiter. wwwaiter is a program for visualizing delays in receiving portions of a document from a web server. It won’t be exact due to buffering done by your webserver and operating system, but it should help diagnose slow parts of web applications.
I recently had a problem on CentOS 5 where the best solution I could think of required running a command when a network interface is brought up. I’m used to having this functionality as a part of the networking scripts on Debian-derived distributions, but I discovered that Red Hat-derived distributions lack it. I’ve written a small daemon called nethook to provide it. You can find the code and documentation for nethook on github.
Virt-install with kvm
If you are using virt-install to create KVM virtual machines on RHEL or CentOS 5, be sure to specify the ‘–accelerate’ option. If you don’t use accelerate, virt-install starts ‘/usr/bin/qemu-system-x86_64’ rather than ‘/usr/libexec/qemu-kvm’. This isn’t what you want, and it will fail with the error message “internal error Domain $YOUR_VM didn’t show up”. What happened in the background is that libvirt set the machine type to rhel5.4.0, which lets qemu-kvm know it can use virtio, but this machine type is not understood by qemu-system-x86_64. If you check ‘/var/log/libvirt/qemu/$YOUR_VM.log’, you’ll see a detailed error like \ \
Collectd encryption error
If you receive the following messages when starting collectd \