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Merge "Add details on target_raid_config for Software RAID support"

Zuul 1 week ago
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997e184cc9
1 changed files with 42 additions and 3 deletions
  1. 42
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      specs/approved/software-raid.rst

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