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author | Zuul <zuul@review.opendev.org> | 2021-12-16 15:58:16 +0000 |
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committer | Gerrit Code Review <review@openstack.org> | 2021-12-16 15:58:16 +0000 |
commit | 17a0f69c6c4aac9169a5ea8981d070bd8eef216e (patch) | |
tree | 4be12da7925cdce4fd8029bb7488cebab6843512 /doc | |
parent | 19cafb55e134cf95477e9a7eff1542a6fae7dc6d (diff) | |
parent | 454ad95666ac6b21f733455159336e4574bedde4 (diff) | |
download | ironic-17a0f69c6c4aac9169a5ea8981d070bd8eef216e.tar.gz |
Merge "Update RAID docs"
Diffstat (limited to 'doc')
-rw-r--r-- | doc/source/admin/raid.rst | 45 |
1 files changed, 41 insertions, 4 deletions
diff --git a/doc/source/admin/raid.rst b/doc/source/admin/raid.rst index 8ed813439..cd9529f99 100644 --- a/doc/source/admin/raid.rst +++ b/doc/source/admin/raid.rst @@ -389,16 +389,35 @@ There are certain limitations to be aware of: "step": "create_configuration" }] -* If local boot is going to be used, the final instance image must have the - ``mdadm`` utility installed and needs to be able to detect software RAID - devices at boot time (which is usually done by having the RAID drivers - embedded in the image's initrd). +* The final instance image must have the ``mdadm`` utility installed + and needs to be able to detect software RAID devices at boot time + (which is usually done by having the RAID drivers embedded in the + image's initrd). * Regular cleaning will not remove RAID configuration (similarly to hardware RAID). To destroy RAID run the ``delete_configuration`` manual clean step. * There is no support for partition images, only whole-disk images are supported with Software RAID. See :doc:`/install/configure-glance-images`. + This includes flavors requesting dynamic creation of swap filesystems. + Swap should be pre-allocated inside of a disk image partition layout. + +* Images utilizing LVM for their root filesystem are not supported. Patches + are welcome to explicitly support such functionality. + +* If the root filesystem UUID is not known to Ironic via metadata, then the + disk image layout **MUST** have the first partition consist of the root + filesystem. Ironic is agnostic if the partition table is a DOS MBR or a + GPT partition. + + Starting in Ironic 14.0.0 (Ussuri), the root filesystem UUID can be set + and passed through to Ironic through the Glance Image Service ``properties`` + sub-field ``rootfs_uuid`` for the image to be deployed. + + Starting in Ironic 16.1.0 (Wallaby), similar functionality is available + via the baremetal node ``instance_info`` field value ``image_rootfs_uuid``. + See :doc:`/install/standalone` for more details on standalone usage + including an example command. * In UEFI mode, the Ironic Python Agent creates EFI system partitions (ESPs) for the bootloader and the boot configuration (grub.cfg or grubenv) on all @@ -420,6 +439,24 @@ There are certain limitations to be aware of: the ones stored in /boot (stage2). This incompatibility can render the node unbootable if the wrong disk is selected for booting. +* Linux kernel device naming is not consistent across reboots for RAID devices + and may be numbered in a distribution specific pattern. Operators will need + to be mindful of this if a root device hint is utilized. + A particular example of this is that the first "md0" device on a Ubuntu + based ramdisk may start as device "md0", whereas on a Centos or Red Hat + Enterprise Linux based ramdisk may start at device "md127". After a reboot, + these device names may change entirely. + + .. NOTE:: + :ref:`Root device hints <root-device-hints>` should not be explicitly + required to utilize software RAID. Candidate devices are chosen by + sorting the usable device list looking for the smallest usable + device which is then sorted by name. The secondary sort by name + improves the odds for matching the first initialized block device. + In the case of software RAID, they are always a little smaller than + the primary block devices due to metadata overhead, which helps make + them the most likely candidate devices. + Image requirements ------------------ |