doc: add a page explaining storage class parameters

 & incorporate review feedback

Signed-off-by: James Munson <[email protected]>

content/docs/1.6.0/advanced-resources/orphaned-data-cleanup.md

@@ -147,4 +147,4 @@ Longhorn will not create an `orphan` resource for an orphaned directory when
   - The volume volume.meta file is missing.
 - The orphaned replica directory is on an evicted node.
 - The orphaned replica directory is in an evicted disk.
-- The orphaned data cleanup mechanism does not clean up a stable replica, also known as an error replica. Instead, the stale replica is cleaned up according to the [staleReplicaTimeout](../../volumes-and-nodes/create-volumes/#creating-longhorn-volumes-with-kubectl) setting.
+- The orphaned data cleanup mechanism does not clean up a stale replica, also known as an error replica. Instead, the stale replica is cleaned up according to the [staleReplicaTimeout](../../volumes-and-nodes/create-volumes/#creating-longhorn-volumes-with-kubectl) setting.

content/docs/1.6.0/references/storage-class-parameters.md

@@ -0,0 +1,154 @@
+---
+title: Storage Class Parameters
+weight: 1
+---
+
+## Overview
+
+Storage Class as a resource object has a number of settable parameters.  Here's a sample YAML:
+```yaml
+kind: StorageClass
+apiVersion: storage.k8s.io/v1
+metadata:
+  name: longhorn-test
+provisioner: driver.longhorn.io
+allowVolumeExpansion: true
+reclaimPolicy: Delete
+volumeBindingMode: Immediate
+parameters:
+  numberOfReplicas: "3"
+  staleReplicaTimeout: "2880"
+  fromBackup: ""
+  fsType: "ext4"
+  diskSelector: "ssd,fast"
+  nodeSelector: "storage,fast"
+#  recurringJobSelector: '[{"name":"snap-group", "isGroup":true},
+#                          {"name":"backup", "isGroup":false}]'
+```
+
+Some fields are common to all Kubernetes storage classes.
+See also [Kubernetes Storage Class](https://kubernetes.io/docs/concepts/storage/storage-classes).  
+
+#### Provisioner
+Specifies the plugin that will be used for dynamic creation of persistent volumes.  For Longhorn, that is always "driver.longhorn.io"
+
+#### Allow Volume Expansion
+> Default: `true`
+
+#### Reclaim Policy
+> Default: `Delete`
+
+#### Volume Binding Mode
+> Default `Immediate`
+
+## Longhorn-specific Parameters
+Note that some of these parameters also exist and may be specified in global settings.  When a volume is provisioned with Kubernetes against a particular StorageClass, StorageClass parameters override the global settings.
+
+#### Number Of Replicas
+> Default: `3`  
+
+The desired number of copies (replicas) for redundancy.  
+  - Must be between 1 and 20.  
+  - Replicas will be placed across the widest possible set of zones, nodes, and disks in a cluster, subject to other constraints, such as [Node Selector](#node-selector).  
+
+> Global setting: [Default Replica Count](../settings#default-replica-count).
+
+#### Stale Replica Timeout
+> Default: `30`
+
+Minutes after a replica is marked unhealthy before it is deemed useless for rebuilds and is just deleted.
+
+#### From Backup
+> Default: `""`  
+> Example: `"s3://backupbucket@us-east-1?volume=minio-vol01&backup=backup-eeb2782d5b2f42bb"`
+
+URL of a backup to be restored from.
+
+#### FS Type
+> Default: `ext4`  
+> For more details, see [Creating Longhorn Volumes with Kubernetes](../../volumes-and-nodes/create-volumes#creating-longhorn-volumes-with-kubectl)
+
+#### Mkfs Params
+> Default: `""`  
+> For more details, see [Creating Longhorn Volumes with Kubernetes](../../volumes-and-nodes/create-volumes#creating-longhorn-volumes-with-kubectl)
+
+#### Migratable
+> Default: `false`  
+
+Allows for a Longhorn volume to be live migrated from one node to another.  Useful for volumes used by Harvester.
+
+#### Encrypted
+> Default: `false`  
+> More details in [Encrypted Volumes](../../advanced-resources/security/volume-encryptiom)
+
+#### Data Locality
+> Default: `disabled`  
+
+If enabled, try to keep the data on the same node as the workload for better performance.  
+  - For "best-effort", a replica will be co-located if possible, but is permitted to find another node if not.  
+  - For "strict-local" the Replica count should be 1, or volume creation will fail with a parameter validation error.  
+  - If "strict-local" is not possible for whatever other reason, volume creation will be failed.  A "strict-local" replica that becomes displaced from its workload will be marked as "Stopped".  
+
+>  Global setting: [Default Data Locality](../settings#default-data-locality)  
+>  More defails in [Data Locality](../../high-availability/data-locality).
+
+#### Replica Auto-Balance
+> Default: `ignored`  
+
+If enabled, move replicas to more lightly-loaded nodes.  
+  - "ignored" means use the global setting.  
+  - Other options are "disabled", "least-effort", "best-effort."  
+
+> Global setting: [Replica Auto Balance](../settings#replica-auto-balance)  
+> More details in [Auto Balance Replicas](../../high-availability/auto-balance-replicas).
+
+#### Disk Selector
+> Default: `""`  
+> Example: `"ssd,fast"`  
+
+A list of tags to select which disks are candidates for replica placement.  
+> More details in [Storage Tags](../../volumes-and-nodes/storage-tags)
+
+#### Node Selector
+> Default: `""`  
+> Example: `"storage,fast"`  
+
+A list of tags to select which nodes are candidates for replica placement.  
+> More details in [Storage Tags](../../volumes-and-nodes/storage-tags)
+
+#### Recurring Jobs Selector
+A list of recurring jobs that are to be run on a volume.  
+> Default: `""`  
+> Example:  `[{"name":"backup", "isGroup":true}]`  
+
+>  More details in [Recurring Snapshots and Backups](../../snapshots-and-backups/scheduling-backups-and-snapshots) 
+	
+#### Backing Image Name
+> Default: `""`  
+> See [Backing Images](../../advanced-resources/backing-images#create-and-use-a-backing-image-via-storageclass-and-pvc)
+
+#### Backing Image Checksum
+> Default: `""`  
+> See [Backing Images](../../advanced-resources/backing-images#create-and-use-a-backing-image-via-storageclass-and-pvc)
+
+#### Backing Image Data Source Type
+> Default: `""`  
+> See [Backing Images](../../advanced-resources/backing-images#create-and-use-a-backing-image-via-storageclass-and-pvc)
+
+#### Backing Image Data Source Parameters
+> Default: `""`  
+> See [Backing Images](../../advanced-resources/backing-images#create-and-use-a-backing-image-via-storageclass-and-pvc)
+
+#### Remove Snapshots During Filesystem Trim
+> Default: `ignored`  
+
+  - "ignored" means use the global setting.  
+  - Other values are "enabled" and "disabled.  
+
+> Global setting: [Remove Snapshots During Filesystem Trim](../settings#remove-snapshots-during-filesystem-trim).  
+> More details in [Trim Filesystem](../../volumes-and-nodes/trim-filesystem).
+
+## Helm Installs
+
+If Longhorn is installed via Helm, values in the default storage class can be set by editing the corresponding item in [values.yaml](https://github.com/longhorn/longhorn/blob/v{{< current-version >}}/chart/values.yaml).  All of the Storage Class parameters have a prefix of "persistence".  For example, `persistence.defaultNodeSelector`.
+