Setting the Root Device for Deployment¶
If your hardware has several hard drives, it’s highly recommended that you
specify the exact device to be used during introspection and deployment
as a root device. This is done by setting a root_device property on the
node in Ironic. Please refer to the Ironic root device hints documentation
for more details.
For example:
ironic node-update <UUID>> add properties/root_device='{"wwn": "0x4000cca77fc4dba1"}'
To remove a hint and fallback to the default behavior:
ironic node-update <UUID> remove properties/root_device
Note that the root device hints should be assigned before both introspection
and deployment. After changing the root device hints you should either re-run
introspection or manually fix the local_gb property for a node:
ironic node-update <UUID> add properties/local_gb=<NEW VALUE>
Where the new value is calculated as a real disk size in GiB minus 1 GiB to account for partitioning (the introspection process does this calculation automatically).
Setting root device hints automatically¶
Starting with the Newton release it is possible to autogenerate root
device hints for all nodes instead of setting them one by one. Pass the
--root-device argument to the openstack overcloud node
configure after a successful introspection. This argument can
accept a device list in the order of preference, for example:
openstack overcloud node configure --all-manageable --root-device=sdb,sdc,vda
It can also accept one of two strategies: smallest will pick the smallest
device, largest will pick the largest one. By default only disk devices
larger than 4 GiB are considered at all, set the --root-device-minimum-size
argument to change.
Note
Subsequent runs of this command on the same set of nodes does nothing, as root device hints are already recorded on nodes and are not overwritten. If you want to change existing root device hints, first remove them manually as described above.
Note
This command relies on introspection data, so if you change disk devices on the machines, introspection must be rerun before rerunning this command.
Using introspection data to find the root device¶
If you don’t know the information required to make a choice, you can use introspection to figure it out. First start with Introspect Nodes as usual without setting any root device hints. Then use the stored introspection data to list all disk devices:
openstack baremetal introspection data save fdf975ae-6bd7-493f-a0b9-a0a4667b8ef3 | jq '.inventory.disks'
For python-ironic-inspector-client versions older than 1.4.0 you can use
the curl command instead, see Accessing Introspection Data for details.
This command will yield output similar to the following (some fields are empty for a virtual node):
[
{
"size": 11811160064,
"rotational": true,
"vendor": "0x1af4",
"name": "/dev/vda",
"wwn_vendor_extension": null,
"wwn_with_extension": null,
"model": "",
"wwn": null,
"serial": null
},
{
"size": 11811160064,
"rotational": true,
"vendor": "0x1af4",
"name": "/dev/vdb",
"wwn_vendor_extension": null,
"wwn_with_extension": null,
"model": "",
"wwn": null,
"serial": null
}
]
You can use all these fields, except for rotational, for the root device
hints. Note that size should be converted to GiB and that name,
wwn_with_extension and wwn_vendor_extension can only be used starting
with the Mitaka release. Also note that the name field, while convenient,
may be unreliable and change between boots.
Do not forget to re-run the introspection after setting the root device hints.
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