Linux - The Next GenerationWhile investigating ZFS snapshot problems I was looking into Ubuntu 24.04 initial RAM disks (initrd/initramfs). So here’s what I found. Unpacking RAM disk Over the years many different ways to pack a RAM disk were used (things like cpio archives, squashfs, and so on). Since it has been a long time since I was forced […]
ZFS comes with quite a set of features. However when upgrading zfs, new features are not enabled by default for compatibility reasons. This may be reported by zpool status: In order to get more information about possible new features you can use zpool upgrade: You can add option -v to get more detailed information about […]
The tests were done on a Quad-Core i5 system, using a 24 GB RAM disk (32 GB RAM total). System is Ubuntu 20.04 (x86_64). Basic test were done using fio with variations of this command: The different benchmark scenarios are these: Create filesystem on RAM disk, create big test file, run fio. And the same […]
Update 11.12.2021: Finally got a new test machine and started re-evaluating the current situation. The tests were done on a Quad-Core i5 system, using a 24 GB RAM disk (32 GB RAM total). System is Ubuntu 20.04 (x86_64). Basic test were done using fio with variations of this command: The different benchmark scenarios are these: […]
Building kernel modules To build the kernel modules we first need to install the kernel sources matching the latest kernel. So first we download and install the required packages: And now prepare a kernel source tree for compilation: Now we should have the very same source tree that build our currently running kernel (well at […]
Interested in how performance estimates can be done and what’s the theory behind it? You’re lucky: Here we go. As a start we need some numbers to work with. We got them here by doing some benchmarks with a RAM disk and the Linux cryptsetup tool. Both tests report the maximum possible performance of each […]