LVM RAID raid0 level support (linux-system-roles#272)

* Add workaround for missing LVM raid0 support in blivet

Blivet supports creating LVs with segment type "raid0" but it is
not in the list of supported RAID levels. This will be fixed in
blivet, see storaged-project/blivet#1047

* Add a test for LVM RAID raid0 level

* README: Remove "striped" from the list of supported RAID for pools

We use MD RAID for RAIDs on the pool level which doesn't support
"striped" level.

* README: Clarify supported volume RAID levels

We support different levels for LVM RAID and MD RAID.

README.md

@@ -53,7 +53,7 @@ device node basename (like `sda` or `mpathb`), /dev/disk/ symlink
 ##### `raid_level`
 When used with `type: lvm` it manages a volume group with a mdraid array of given level
 on it. Input `disks` are in this case used as RAID members.
-Accepted values are: `linear`, `striped`, `raid0`, `raid1`, `raid4`, `raid5`, `raid6`, `raid10`
+Accepted values are: `linear`, `raid0`, `raid1`, `raid4`, `raid5`, `raid6`, `raid10`
 
 ##### `volumes`
 This is a list of volumes that belong to the current pool. It follows the
@@ -135,7 +135,10 @@ Specifies RAID level. LVM RAID can be created as well.
 "Regular" RAID volume requires type to be `raid`.
 LVM RAID needs that volume has `storage_pools` parent with type `lvm`,
 `raid_disks` need to be specified as well.
-Accepted values are: `linear` (N/A for LVM RAID), `striped`, `raid0`, `raid1`, `raid4`, `raid5`, `raid6`, `raid10`
+Accepted values are:
+* for LVM RAID volume: `raid0`, `raid1`, `raid4`, `raid5`, `raid6`, `raid10`, `striped`, `mirror`
+* for RAID volume: `linear`, `raid0`, `raid1`, `raid4`, `raid5`, `raid6`, `raid10`
+
 __WARNING__: Changing `raid_level` for a volume is a destructive operation, meaning
              all data on that volume will be lost as part of the process of
              removing old and adding new RAID. RAID reshaping is currently not

library/blivet.py

@@ -117,6 +117,7 @@
 try:
     from blivet3 import Blivet
     from blivet3.callbacks import callbacks
+    from blivet3 import devicelibs
     from blivet3 import devices
     from blivet3.deviceaction import ActionConfigureFormat
     from blivet3.devicefactory import DEFAULT_THPOOL_RESERVE
@@ -132,6 +133,7 @@
     try:
         from blivet import Blivet
         from blivet.callbacks import callbacks
+        from blivet import devicelibs
         from blivet import devices
         from blivet.deviceaction import ActionConfigureFormat
         from blivet.devicefactory import DEFAULT_THPOOL_RESERVE
@@ -153,6 +155,11 @@
     set_up_logging()
     log = logging.getLogger(BLIVET_PACKAGE + ".ansible")
 
+    # XXX add support for LVM RAID raid0 level
+    devicelibs.lvm.raid_levels.add_raid_level(devicelibs.raid.RAID0)
+    if "raid0" not in devicelibs.lvm.raid_seg_types:
+        devicelibs.lvm.raid_seg_types.append("raid0")
+
 
 MAX_TRIM_PERCENT = 2
 

tests/tests_create_raid_pool_then_remove.yml

@@ -150,3 +150,57 @@
                 raid_disks: "{{ [unused_disks[0], unused_disks[1]] }}"
 
     - include_tasks: verify-role-results.yml
+
+    - name: Create a RAID0 lvm raid device
+      include_role:
+        name: linux-system-roles.storage
+      vars:
+        storage_pools:
+          - name: vg1
+            disks: "{{ unused_disks }}"
+            type: lvm
+            state: present
+            volumes:
+              - name: lv1
+                size: "{{ volume1_size }}"
+                mount_point: "{{ mount_location1 }}"
+                raid_disks: "{{ [unused_disks[0], unused_disks[1]] }}"
+                raid_level: raid0
+
+    - include_tasks: verify-role-results.yml
+
+    - name: Repeat the previous invocation to verify idempotence
+      include_role:
+        name: linux-system-roles.storage
+      vars:
+        storage_pools:
+          - name: vg1
+            disks: "{{ unused_disks }}"
+            type: lvm
+            state: present
+            volumes:
+              - name: lv1
+                size: "{{ volume1_size }}"
+                mount_point: "{{ mount_location1 }}"
+                raid_level: raid0
+                raid_disks: "{{ [unused_disks[0], unused_disks[1]] }}"
+
+    - include_tasks: verify-role-results.yml
+
+    - name: Remove the device created above
+      include_role:
+        name: linux-system-roles.storage
+      vars:
+        storage_pools:
+          - name: vg1
+            disks: "{{ unused_disks }}"
+            type: lvm
+            state: absent
+            volumes:
+              - name: lv1
+                size: "{{ volume1_size }}"
+                mount_point: "{{ mount_location1 }}"
+                raid_level: raid0
+                raid_disks: "{{ [unused_disks[0], unused_disks[1]] }}"
+
+    - include_tasks: verify-role-results.yml