openstack
/
ironic-specs
Code Issues Proposed changes

Add details on target_raid_config for Software RAID support 

This patch adds some details on how the target_raid_config for
Software RAID support is supposed to look like: the 'controller'
property is used to signal that a configuration is intended for
a Software RAID setup and is also used to trigger the installation
of a bootloader for whole disk images (which is not needed otherwise).

Change-Id: I3b8191f7653d2dccbcb0dd6b45b5b94cb56ba4cf
Story: #2004581
Task: #28366
This commit is contained in:
Arne Wiebalck 2019-03-13 17:22:40 +01:00
parent 56096250d6
commit 6053cae0cd
1 changed files with 42 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

45
specs/approved/software-raid.rst
View File

@ -75,10 +75,49 @@ configurations: a RAID-1 holder device can look like a standalone disk and does
not require the bootloader to have any knowledge or capabilities to understand not require the bootloader to have any knowledge or capabilities to understand
more complex RAID configurations. more complex RAID configurations.
In order to signal that a software RAID configuration is indeed desired (and
to protect from a situation where a software RAID is set up accidentally
when the configuration passed via the ``target_raid_config`` was meant for a
hardware RAID setup, for instance), the ``controller`` property of all of the
logical disks needs to be set to ``software``. Without this setting, the
software RAID code in the GenericHardwareManager of the IPA will ignore the
given ``target_raid_config``. If it is set on only one of the logical drives,
the validation code will raise an error.
The ``controller`` property set to ``software`` will also be used by the
conductor to identify a software RAID and trigger the required installation of
the bootloader. While whole-disk images are expected to come with a bootloader
configuration as part of the image, for software RAIDs in the current design
the image will not be at the start of a real disk, but inside the first
partition on top of a software RAID-1. The bootloader must hence be explicitly
installed onto the underlying holder disks, and this property will indicate
when to do this.
An example of a valid software RAID configuration would hence look like::
{
"logical_disks": [
{
"size_gb": 100,
"raid_level": "1",
"controller": "software"
},
{
"size_gb": "MAX",
"raid_level": "0",
"controller": "software"
}
]
}
Support for more than one RAID-N, support for the selection of a subset of Support for more than one RAID-N, support for the selection of a subset of
drives to act as holder devices, as well as support to partition the created drives to act as holder devices, support for simultaneous software and
RAID-N device are left for follow-up enhancements and beyond the scope of hardware RAID devices as well as support to partition the created RAID-N
this specification. device are left for follow-up enhancements and beyond the scope of this
specification.
Also, there is currently no support for partition images, only whole disk
images are supported.
A first prototype very close to the proposal is available from [2][3][4]. A first prototype very close to the proposal is available from [2][3][4].