Avoiding common pitfalls

7.1 LPAR mode z/VM guest KVM guest

Common problems and how to avoid them.

Ensuring a 25 GB RoCE connection to a CISCO switch works
Using a RoCE adapter with a 25-Gigabit Ethernet connection to a Cisco switch requires a special setting.
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 z/VM guest swapping
Avoid excessive guest swapping by using the timed page pool size and the static page pool size attributes.
Booting stops with disabled wait state
An automatic processor type check might stop the boot process with a disabled wait PSW.
LPAR auto-configuration overrides persistent configuration
After upgrading Linux®, persistent device configurations that were specified with chzdev are overridden with the auto-configuration.
Preparing for dump-on-panic
Set 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