"Resource temporarily unavailble" messages on system boot while setting DASDs or MDISKs online

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Environment

SUSE Linux Enterprise Server 15 for IBM Z (all service packs)

Situation

Messages referring to a resource being temporarily unavailable while setting a DASD or MDISK online appear on boot:

(udev-worker)[1234]: dasd-eckd: /etc/udev/rules.d/41-dasd-eckd-0.0.0155.rules:8 Failed to write ATTR{/sys/devices/css0/0.0.0020/0.0.0155/online}, ignoring: Resource temporarily unavailable

However, all disks appear to be present in the running system.

Resolution

These messages are harmless and can be ignored.

Cause

When the CSS driver discovers and registers a new device, it generates an ADD udev event, which gets processed by the udev daemon according to the udev rules for this event. Sometimes, the actual device behind this channel isn't fully initialized yet at this point in time, which results in the observed log messages. When the device, for example a DASD or MDISK, is ready, its driver will generate another ADD event and the udev daemon can successfully set the device online.

Disclaimer

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