The linstor module: configuration

This feature is actively developed. It might significantly change in the future.

The module is not enabled by default in any bundles.

Set the spec.enabled module parameter to true or false to explicitly enable or disable the module.

Example of enabling the linstor module:

          apiVersion: deckhouse.io/v1alpha1
kind: ModuleConfig
metadata:
  name: linstor
spec:
  enabled: true

        

Example of disabling the linstor module:

          apiVersion: deckhouse.io/v1alpha1
kind: ModuleConfig
metadata:
  name: linstor
spec:
  enabled: false

        

The functionality of the module is guaranteed only for stock kernels for distributions listed in the list of supported OS. The functionality of the module with other kernels is possible but not guaranteed.

After enabling the module, the cluster is automatically configured to use LINSTOR, and all that remains is to configure the storage.

The module requires no configuration and has no parameters. However, some functions may require a master passphrase.
To set a master passphrase, create a Secret in the d8-system namespace:

apiVersion: v1
kind: Secret
metadata:
  name: linstor-passphrase
  namespace: d8-system
immutable: true
stringData:
  MASTER_PASSPHRASE: *!passphrase* # Master passphrase for LINSTOR

Warning: Choose strong passphrase and store it securely. If it get lost, the encrypted data will be inaccessible.

LINSTOR storage configuration

LINSTOR in Deckhouse can be configured by assigning special tag linstor-<pool_name> to an LVM volume group or LVMThin pool.

Choose the tag name.

The tag name must be unique within the same node. Therefore, before assigning a new tag, make sure that other volume groups and thin pools do not have this tag already.

Execute the following commands to get list volume groups and pools:
```
# LVM pools
vgs -o name,tags | awk 'NR==1;$2~/linstor-/'
# LVMThin pools
lvs -o name,vg_name,tags | awk 'NR==1;$3~/linstor-/'
```
Add pools.

Add pools on all nodes where you plan to store your data. Use the same names for the storage pools on the different nodes if you want to achieve a general StorageClasses created for all of them.
- To add an LVM pool, create a volume group with the linstor-<pool_name> tag, or the linstor-<pool_name> tag to an existing volume group.
  
  Example of command to create a volume group vg0 with the linstor-data tag :
```
vgcreate vg0 /dev/nvme0n1 /dev/nvme1n1 --add-tag linstor-data
```
  Example of command to add the linstor-data tag to an existing volume group vg0:
```
vgchange vg0 --add-tag linstor-data
```
- To add an LVMThin pool, create a LVM thin pool with the linstor-<pool_name> tag.
  
  Example of command to create the LVMThin pool vg0/thindata with the linstor-data tag:
```
vgcreate vg0 /dev/nvme0n1 /dev/nvme1n1
lvcreate -l 100%FREE -T vg0/thindata --add-tag linstor-thindata
```
  Note, that the group itself should not have this tag configured.
Check the creation of StorageClass.

Three new StorageClasses will appear when all the storage pools have been created. Check that they were created by running the following command in the Kubernetes cluster:
```
kubectl get storageclass
```
Example of the output:
```
$ kubectl get storageclass
NAME                   PROVISIONER                  AGE
linstor-data-r1        linstor.csi.linbit.com       143s
linstor-data-r2        linstor.csi.linbit.com       142s
linstor-data-r3        linstor.csi.linbit.com       142s
```
Each StorageClass can be used to create volumes with one, two, or three replicas in your storage pools, respectively.

You can always refer to Advanced LINSTOR Configuration if needed, but we strongly recommend sticking to this simplified guide.