[openstack-dev] [ironic] Backward incompatibility when moving from the old Ironic ramdisk to ironic-python-agent

Dmitry Tantsur dtantsur at redhat.com
Wed Mar 16 16:18:06 UTC 2016

Hi all!

This is a heads up for you that we've found an issue [1] in IPA that 
changes the behavior for those of you with several hard drives. The 
difference is in the way our ramdisks pick the root device for 
deployment, when no root device hints [2] are provided. Namely:
- The old ramdisk picked the first available device from the list of 
device names in the "disk_devices" configuration option [3]. In practice 
it usually meant the first disk was chosen. Note that this approach was 
error-prone, as disk ordering is, generally speaking, not guaranteed by 
- IPA ignores the "disk_devices" option completely and picks the 
smallest device larger than 4 GiB.

It is probably too late to change the IPA behavior to be more 
compatible, as a lot of folks are already relying on it. So we decided 
to raise this issue and get feedback on the preferred path forward.

[1] https://bugs.launchpad.net/ironic-python-agent/+bug/1554492

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