Avoiding common pitfalls

Ubuntu 22.04 LTS LPAR mode z/VM guest KVM guest

Common problems and how to avoid them.

Ensuring correct channel path status
Ensure that you varied the path offline before you perform a planned task on it.
Determining channel path usage on LPAR
To determine the usage of a specific channel path on LPAR, for example, to check whether traffic is distributed evenly over all channel paths, use the channel path measurement facility.
Ignore unnecessary I/O devices
An instance of Linux® on IBM® Z should ignore all I/O devices that it does not currently use.
Using cio_ignore
With cio_ignore, essential devices might be hidden.
Excessive guest swapping
Avoid excessive guest swapping by using the timed page pool size and the static page pool size attributes.
Including service levels of the hardware and the hypervisor
The service levels of the different hardware cards, the LPAR level, and the z/VM® service level are valuable information for problem analysis.
Booting stops with disabled wait state
An automatic processor type check might stop the boot process with a disabled wait PSW.
Preparing for dump-on-panic
You might want to consider setting up your system to automatically create a memory dump after a kernel panic.
Function unavailable or degraded in Linux on z/VM
For some functions, Linux on z/VM issues diagnose instructions to the z/VM hypervisor.

Parent topic: Diagnostics and troubleshooting