When a Mayastor Node (MSN) allocates storage capacity for a Persistent Volume (PV) it does so from a construct named a Mayastor Pool (MSP). Each MSN may create and manage zero, one, or more such pools. The ownership of a pool by a MSN is exclusive. In the current version of Mayastor, a pool may have only a single block device member, which constitutes the entire data persistence layer for that pool and thus determines its maximum capacity.
A pool is defined declaratively, through the creation of a corresponding
MayastorPoolcustom resource (CR) on the cluster. User configurable parameters of this CR type include a unique name for the pool, the host name of the MSN on which it is hosted and a reference to a disk device which is accessible from that node (for inclusion within the pool). The pool definition allows the reference to its member block device to adhere to one of a number of possible schemes, each associated with a specific access mechanism/transport/device type and differentiated by corresponding performance and/or attachment locality.
Attached Disk Device (AIO)
Async. Disk I/O (AIO)
Once a Mayastor node has created a pool it is assumed that it henceforth has exclusive use of the associated block device; it should not be partitioned, formatted, or shared with another application or process. Any existing data on the device will be destroyed.
To continue with this quick start exercise, a minimum of one pool is necessary, created and hosted by one of the MSNs in the cluster. However the number of pools available limits the extent to which the synchronous n-way mirroring feature ("replication") of Persistent Volumes can configured for testing and evaluation; the number of pools configured should be no lower than the desired maximum replication factor of the PVs to be created. Note also that when placing data replicas, to provide appropriate redundancy, Mayastor's control plane will avoid locating more than one replica of a PV on the same MSN. Therefore, for example, the minimum viable configuration for a Mayastor deployment which is intended to test 3-way mirrored PVs must have three Mayastor Nodes, each having one Mayastor Pool, with each of those pools having one unique block device allocated to it.
Using one or more the following examples as templates, create the required type and number of pools.
cat <<EOF | kubectl create -f -apiVersion: "openebs.io/v1alpha1"kind: MayastorPoolmetadata:name: pool-on-node-1namespace: mayastorspec:node: workernode-1-hostnamedisks: ["/dev/sdx"]EOF
apiVersion: "openebs.io/v1alpha1"kind: MayastorPoolmetadata:name: INSERT_POOL_NAME_HEREnamespace: mayastorspec:node: INSERT_WORKERNODE_HOSTNAME_HEREdisks: ["INSERT_DEVICE_URI_HERE"]
The status of Mayastor Pools may be determined by reference to their cluster CRs. Available, healthy pools should report their State as
online. Verify that the expected number of pools have been created and that they are online.
kubectl -n mayastor get msp
NAME NODE STATE AGEpool-on-node-0 aks-agentpool-12194210-0 online 127mpool-on-node-1 aks-agentpool-12194210-1 online 27spool-on-node-2 aks-agentpool-12194210-2 online 4s
Mayastor dynamically provisions Persistent Volumes (PV) based on custom StorageClass definitions defined by the user. Parameters of the StorageClass resource definition are used to set the characteristics and behaviour of its associated PVs. For detailed description of the parameters see "local" storage class parameter description. Most importantly StorageClass definition is used to control the level of data protection afforded to it (that is, the number of synchronous data replicas which are maintained, for purposes of redundancy). It is possible to create any number of custom StorageClass definitions to span range of storage class parameters permutations.
We illustrate this quickstart guide with two examples of possible use cases; one which offers no data protection (i.e. a single data replica), and another having three data replicas. You may modify these as required to match your own desired test cases, within the limitations of the cluster under test.
cat <<EOF | kubectl create -f -kind: StorageClassapiVersion: storage.k8s.io/v1metadata:name: mayastor-1parameters:repl: '1'protocol: 'nvmf'ioTimeout: 60local: trueprovisioner: io.openebs.csi-mayastorvolumeBindingMode: WaitForFirstConsumerEOF
cat <<EOF | kubectl create -f -kind: StorageClassapiVersion: storage.k8s.io/v1metadata:name: mayastor-3parameters:repl: '3'protocol: 'nvmf'ioTimeout: 60local: trueprovisioner: io.openebs.csi-mayastorvolumeBindingMode: WaitForFirstConsumerEOF
Action: Create the StorageClass(es) appropriate to your intended testing scenario(s).