Configuring the root device
Changing the configuration of the device that provides the root file system might require additional configuration steps. Which steps are taken depends on whether the Linux® instance uses a RAM disk during boot.
Before you begin
Tool builders: If your Linux uses dracut and a RAM disk, build the
lszdev and chzdev commands with
HAVE_ZDEV_DRACUT=1. Otherwise, build with
HAVE_ZDEV_DRACUT=0.The actions chzdev performs depend on whether the lszdev
and chzdev commands are built with HAVE_ZDEV_DRACUT= set to 0 or
1. 0
implies that there is no RAM disk, 1
implies that the Linux instance uses dracut
and a RAM disk. The chzdev command takes the following actions:
- No RAM disk
- When built with setting
HAVE_ZDEV_DRACUT=0, the chzdev command attempts to update the kernel command line found in file /etc/zipl.conf and run zipl to update the IPL records. - dracut-based RAM disk
- When built with setting
HAVE_ZDEV_DRACUT=1, a new dracut module is installed, which copies the persistent root device configuration to newly built initial RAM disks. Also, when the root device configuration is updated, the dracut command is run to rebuild the RAM disk, followed by zipl to update the IPL records.
Example
# chzdev --by-path / --enable --persistent
Configuring devices in the persistent configuration only
zFCP LUN 0.0.1940:0x500507630508c1ae:0x402140ac00000000 configured
Note: Some of the changes affect devices providing the root file system:
- zFCP LUN 0.0.1940:0x500507630508c1ae:0x402140ac00000000
Additional steps such as rebuilding the RAM-disk might be required.
Update persistent root device configuration now? (yes/no) yes
Building initial RAM-disk
Installing IPL record
Using config file ’/etc/zipl.conf’
Building bootmap in ’/boot’
Building menu ’zipl-automatic-menu’
Adding #1: IPL section ’3.10.0’ (default)
Preparing boot device: sda.
Done.
Note how additional steps are taken to update the IPL records.