This document describes the current state of PersistentVolumes
in Kubernetes. Familiarity with volumes is suggested.
Managing storage is a distinct problem from managing compute. The PersistentVolume
subsystem provides an API for users and administrators that abstracts details of how storage is provided from how it is consumed. To do this we introduce two new API resources: PersistentVolume
and PersistentVolumeClaim
.
A PersistentVolume
(PV) is a piece of storage in the cluster that has been provisioned by an administrator. It is a resource in the cluster just like a node is a cluster resource. PVs are volume plugins like Volumes, but have a lifecycle independent of any individual pod that uses the PV. This API object captures the details of the implementation of the storage, be that NFS, iSCSI, or a cloud-provider-specific storage system.
A PersistentVolumeClaim
(PVC) is a request for storage by a user. It is similar to a pod. Pods consume node resources and PVCs consume PV resources. Pods can request specific levels of resources (CPU and Memory). Claims can request specific size and access modes (e.g., can be mounted once read/write or many times read-only).
While PersistentVolumeClaims
allow a user to consume abstract storage
resources, it is common that users need PersistentVolumes
with varying
properties, such as performance, for different problems. Cluster administrators
need to be able to offer a variety of PersistentVolumes
that differ in more
ways than just size and access modes, without exposing users to the details of
how those volumes are implemented. For these needs there is the StorageClass
resource.
A StorageClass
provides a way for administrators to describe the “classes” of
storage they offer. Different classes might map to quality-of-service levels,
or to backup policies, or to arbitrary policies determined by the cluster
administrators. Kubernetes itself is unopinionated about what classes
represent. This concept is sometimes called “profiles” in other storage
systems.
Please see the detailed walkthrough with working examples.
PVs are resources in the cluster. PVCs are requests for those resources and also act as claim checks to the resource. The interaction between PVs and PVCs follows this lifecycle:
There are two ways PVs may be provisioned: statically or dynamically.
A cluster administrator creates a number of PVs. They carry the details of the real storage which is available for use by cluster users. They exist in the Kubernetes API and are available for consumption.
When none of the static PVs the administrator created matches a user’s PersistentVolumeClaim
, the cluster may try to dynamically provision a volume specially for the PVC. This provisioning is based on StorageClasses
: the PVC must request a class and the administrator must have created and configured that class in order for dynamic provisioning to occur. Claims that request the class ""
effectively disable dynamic provisioning for themselves.
A user creates, or has already created in the case of dynamic provisioning, a PersistentVolumeClaim
with a specific amount of storage requested and with certain access modes. A control loop in the master watches for new PVCs, finds a matching PV (if possible), and binds them together. If a PV was dynamically provisioned for a new PVC, the loop will always bind that PV to the PVC. Otherwise, the user will always get at least what they asked for, but the volume may be in excess of what was requested. Once bound, PersistentVolumeClaim
binds are exclusive, regardless of the mode used to bind them.
Claims will remain unbound indefinitely if a matching volume does not exist. Claims will be bound as matching volumes become available. For example, a cluster provisioned with many 50Gi PVs would not match a PVC requesting 100Gi. The PVC can be bound when a 100Gi PV is added to the cluster.
Pods use claims as volumes. The cluster inspects the claim to find the bound volume and mounts that volume for a pod. For volumes which support multiple access modes, the user specifies which mode desired when using their claim as a volume in a pod.
Once a user has a claim and that claim is bound, the bound PV belongs to the user for as long as they need it. Users schedule Pods and access their claimed PVs by including a persistentVolumeClaim in their Pod’s volumes block. See below for syntax details.
When a user is done with their volume, they can delete the PVC objects from the API which allows reclamation of the resource. The volume is considered “released” when the claim is deleted, but it is not yet available for another claim. The previous claimant’s data remains on the volume which must be handled according to policy.
The reclaim policy for a PersistentVolume
tells the cluster what to do with the volume after it has been released of its claim. Currently, volumes can either be Retained, Recycled or Deleted. Retention allows for manual reclamation of the resource. For those volume plugins that support it, deletion removes both the PersistentVolume
object from Kubernetes, as well as deleting the associated storage asset in external infrastructure (such as an AWS EBS, GCE PD, Azure Disk, or Cinder volume). Volumes that were dynamically provisioned are always deleted.
If supported by appropriate volume plugin, recycling performs a basic scrub (rm -rf /thevolume/*
) on the volume and makes it available again for a new claim.
However, an administrator can configure a custom recycler pod template using the Kubernetes controller manager command line arguments as described here. The custom recycler pod template must contain a volumes
specification, as shown in the example below:
apiVersion: v1
kind: Pod
metadata:
name: pv-recycler-
namespace: default
spec:
restartPolicy: Never
volumes:
- name: vol
hostPath:
path: /any/path/it/will/be/replaced
containers:
- name: pv-recycler
image: "gcr.io/google_containers/busybox"
command: ["/bin/sh", "-c", "test -e /scrub && rm -rf /scrub/..?* /scrub/.[!.]* /scrub/* && test -z \"$(ls -A /scrub)\" || exit 1"]
volumeMounts:
- name: vol
mountPath: /scrub
However, the particular path specified in the custom recycler pod template in the volumes
part is replaced with the particular path of the volume that is being recycled.
PersistentVolume
types are implemented as plugins. Kubernetes currently supports the following plugins:
Each PV contains a spec and status, which is the specification and status of the volume.
apiVersion: v1
kind: PersistentVolume
metadata:
name: pv0003
spec:
capacity:
storage: 5Gi
accessModes:
- ReadWriteOnce
persistentVolumeReclaimPolicy: Recycle
storageClassName: slow
nfs:
path: /tmp
server: 172.17.0.2
Generally, a PV will have a specific storage capacity. This is set using the PV’s capacity
attribute. See the Kubernetes Resource Model to understand the units expected by capacity
.
Currently, storage size is the only resource that can be set or requested. Future attributes may include IOPS, throughput, etc.
A PersistentVolume
can be mounted on a host in any way supported by the resource provider. As shown in the table below, providers will have different capabilities and each PV’s access modes are set to the specific modes supported by that particular volume. For example, NFS can support multiple read/write clients, but a specific NFS PV might be exported on the server as read-only. Each PV gets its own set of access modes describing that specific PV’s capabilities.
The access modes are:
In the CLI, the access modes are abbreviated to:
Important! A volume can only be mounted using one access mode at a time, even if it supports many. For example, a GCEPersistentDisk can be mounted as ReadWriteOnce by a single node or ReadOnlyMany by many nodes, but not at the same time.
Volume Plugin | ReadWriteOnce | ReadOnlyMany | ReadWriteMany |
---|---|---|---|
AWSElasticBlockStore | ✓ | - | - |
AzureFile | ✓ | ✓ | ✓ |
AzureDisk | ✓ | - | - |
CephFS | ✓ | ✓ | ✓ |
Cinder | ✓ | - | - |
FC | ✓ | ✓ | - |
FlexVolume | ✓ | ✓ | - |
Flocker | ✓ | - | - |
GCEPersistentDisk | ✓ | ✓ | - |
Glusterfs | ✓ | ✓ | ✓ |
HostPath | ✓ | - | - |
iSCSI | ✓ | ✓ | - |
PhotonPersistentDisk | ✓ | - | - |
Quobyte | ✓ | ✓ | ✓ |
NFS | ✓ | ✓ | ✓ |
RBD | ✓ | ✓ | - |
VsphereVolume | ✓ | - | - |
PortworxVolume | ✓ | - | ✓ |
ScaleIO | ✓ | ✓ | - |
A PV can have a class, which is specified by setting the
storageClassName
attribute to the name of a
StorageClass
. A PV of a particular class can only be bound to PVCs requesting
that class. A PV with no storageClassName
has no class and can only be bound
to PVCs that request no particular class.
In the past, the annotation volume.beta.kubernetes.io/storage-class
was used instead
of the storageClassName
attribute. This annotation is still working, however
it will become fully deprecated in a future Kubernetes release.
Current reclaim policies are:
Currently, only NFS and HostPath support recycling. AWS EBS, GCE PD, Azure Disk, and Cinder volumes support deletion.
A volume will be in one of the following phases:
The CLI will show the name of the PVC bound to the PV.
A Kubernetes administrator can specify additional mount options for when a Persistent Volume is being mounted on a node.
You can specify a mount option by using the annotation volume.beta.kubernetes.io/mount-options
on
your Persistent Volume.
For example:
apiVersion: "v1"
kind: "PersistentVolume"
metadata:
name: gce-disk-1
annotations:
volume.beta.kubernetes.io/mount-options: "discard"
spec:
capacity:
storage: "10Gi"
accessModes:
- "ReadWriteOnce"
gcePersistentDisk:
fsType: "ext4"
pdName: "gce-disk-1"
A mount option is a string which will be cumulatively joined and used while mounting volume to the disk.
Note that not all Persistent volume types support mount options. In Kubernetes version 1.6, the following volume types support mount options.
Each PVC contains a spec and status, which is the specification and status of the claim.
kind: PersistentVolumeClaim
apiVersion: v1
metadata:
name: myclaim
spec:
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 8Gi
storageClassName: slow
selector:
matchLabels:
release: "stable"
matchExpressions:
- {key: environment, operator: In, values: [dev]}
Claims use the same conventions as volumes when requesting storage with specific access modes.
Claims, like pods, can request specific quantities of a resource. In this case, the request is for storage. The same resource model applies to both volumes and claims.
Claims can specify a label selector to further filter the set of volumes. Only the volumes whose labels match the selector can be bound to the claim. The selector can consist of two fields:
All of the requirements, from both matchLabels
and matchExpressions
are ANDed together – they must all be satisfied in order to match.
A claim can request a particular class by specifying the name of a
StorageClass
using the attribute storageClassName
.
Only PVs of the requested class, ones with the same storageClassName
as the PVC, can
be bound to the PVC.
PVCs don’t necessarily have to request a class. A PVC with its storageClassName
set
equal to ""
is always interpreted to be requesting a PV with no class, so it
can only be bound to PVs with no class (no annotation or one set equal to
""
). A PVC with no storageClassName
is not quite the same and is treated differently
by the cluster depending on whether the
DefaultStorageClass
admission plugin
is turned on.
StorageClass
. All PVCs that have no storageClassName
can be bound only to
PVs of that default. Specifying a default StorageClass
is done by setting the
annotation storageclass.kubernetes.io/is-default-class
equal to “true” in
a StorageClass
object. If the administrator does not specify a default, the
cluster responds to PVC creation as if the admission plugin were turned off. If
more than one default is specified, the admission plugin forbids the creation of
all PVCs.StorageClass
. All PVCs that have no storageClassName
can be bound only to PVs that
have no class. In this case, the PVCs that have no storageClassName
are treated the
same way as PVCs that have their storageClassName
set to ""
.Depending on installation method, a default StorageClass may be deployed to Kubernetes cluster by addon manager during installation.
When a PVC specifies a selector
in addition to requesting a StorageClass
,
the requirements are ANDed together: only a PV of the requested class and with
the requested labels may be bound to the PVC. Note that currently, a PVC with a
non-empty selector
can’t have a PV dynamically provisioned for it.
In the past, the annotation volume.beta.kubernetes.io/storage-class
was used instead
of storageClassName
attribute. This annotation is still working, however
it won’t be supported in a future Kubernetes release.
Pods access storage by using the claim as a volume. Claims must exist in the same namespace as the pod using the claim. The cluster finds the claim in the pod’s namespace and uses it to get the PersistentVolume
backing the claim. The volume is then mounted to the host and into the pod.
kind: Pod
apiVersion: v1
metadata:
name: mypod
spec:
containers:
- name: myfrontend
image: dockerfile/nginx
volumeMounts:
- mountPath: "/var/www/html"
name: mypd
volumes:
- name: mypd
persistentVolumeClaim:
claimName: myclaim
PersistentVolumes
binds are exclusive, and since PersistentVolumeClaims
are namespaced objects, mounting claims with “Many” modes (ROX
, RWX
) is only possible within one namespace.
Each StorageClass
contains the fields provisioner
and parameters
, which
are used when a PersistentVolume
belonging to the class needs to be
dynamically provisioned.
The name of a StorageClass
object is significant, and is how users can
request a particular class. Administrators set the name and other parameters
of a class when first creating StorageClass
objects, and the objects cannot
be updated once they are created.
Administrators can specify a default StorageClass
just for PVCs that don’t
request any particular class to bind to: see the
PersistentVolumeClaim
section
for details.
kind: StorageClass
apiVersion: storage.k8s.io/v1
metadata:
name: standard
provisioner: kubernetes.io/aws-ebs
parameters:
type: gp2
Storage classes have a provisioner that determines what volume plugin is used for provisioning PVs. This field must be specified.
Volume Plugin | Internal Provisioner | Config Example |
---|---|---|
AWSElasticBlockStore | ✓ | AWS |
AzureFile | ✓ | - |
AzureDisk | ✓ | Azure Disk |
CephFS | - | - |
Cinder | ✓ | OpenStack Cinder |
FC | - | - |
FlexVolume | - | - |
Flocker | ✓ | - |
GCEPersistentDisk | ✓ | GCE |
Glusterfs | ✓ | Glusterfs |
iSCSI | - | - |
PhotonPersistentDisk | ✓ | - |
Quobyte | ✓ | Quobyte |
NFS | - | - |
RBD | ✓ | Ceph RBD |
VsphereVolume | ✓ | vSphere |
PortworxVolume | ✓ | Portworx Volume |
ScaleIO | ✓ | ScaleIO |
You are not restricted to specifying the “internal” provisioners listed here (whose names are prefixed with “kubernetes.io” and shipped alongside Kubernetes). You can also run and specify external provisioners, which are independent programs that follow a specification defined by Kubernetes. Authors of external provisioners have full discretion over where their code lives, how the provisioner is shipped, how it needs to be run, what volume plugin it uses (including Flex), etc. The repository kubernetes-incubator/external-storage houses a library for writing external provisioners that implements the bulk of the specification plus various community-maintained external provisioners.
For example, NFS doesn’t provide an internal provisioner, but an external provisioner can be used. Some external provisioners are listed under the repository kubernetes-incubator/external-storage. There are also cases when 3rd party storage vendors provide their own external provisioner.
Persistent Volumes that are dynamically created by a storage class will have a reclaim
policy of delete
. If that is not desired, the only current option is to edit the
PV after it is created.
Persistent Volumes that are created manually and managed via a storage class will have whatever reclaim policy they were assigned at creation.
Storage classes have parameters that describe volumes belonging to the storage
class. Different parameters may be accepted depending on the provisioner
. For
example, the value io1
, for the parameter type
, and the parameter
iopsPerGB
are specific to EBS. When a parameter is omitted, some default is
used.
kind: StorageClass
apiVersion: storage.k8s.io/v1
metadata:
name: slow
provisioner: kubernetes.io/aws-ebs
parameters:
type: io1
zone: us-east-1d
iopsPerGB: "10"
type
: io1
, gp2
, sc1
, st1
. See AWS docs for details. Default: gp2
.zone
: AWS zone. If not specified, volumes are generally round-robin-ed across all active zones where Kubernetes cluster has a node.iopsPerGB
: only for io1
volumes. I/O operations per second per GiB. AWS volume plugin multiplies this with size of requested volume to compute IOPS of the volume and caps it at 20 000 IOPS (maximum supported by AWS, see AWS docs. A string is expected here, i.e. "10"
, not 10
.encrypted
: denotes whether the EBS volume should be encrypted or not. Valid values are "true"
or "false"
. A string is expected here, i.e. "true"
, not true
.kmsKeyId
: optional. The full Amazon Resource Name of the key to use when encrypting the volume. If none is supplied but encrypted
is true, a key is generated by AWS. See AWS docs for valid ARN value.kind: StorageClass
apiVersion: storage.k8s.io/v1
metadata:
name: slow
provisioner: kubernetes.io/gce-pd
parameters:
type: pd-standard
zone: us-central1-a
type
: pd-standard
or pd-ssd
. Default: pd-standard
zone
: GCE zone. If not specified, volumes are generally round-robin-ed across all active zones where Kubernetes cluster has a node.apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
name: slow
provisioner: kubernetes.io/glusterfs
parameters:
resturl: "http://127.0.0.1:8081"
clusterid: "630372ccdc720a92c681fb928f27b53f"
restauthenabled: "true"
restuser: "admin"
secretNamespace: "default"
secretName: "heketi-secret"
gidMin: "40000"
gidMax: "50000"
volumetype: "replicate:3"
resturl
: Gluster REST service/Heketi service url which provision gluster volumes on demand. The general format should be IPaddress:Port
and this is a mandatory parameter for GlusterFS dynamic provisioner. If Heketi service is exposed as a routable service in openshift/kubernetes setup, this can have a format similar to
http://heketi-storage-project.cloudapps.mystorage.com
where the fqdn is a resolvable heketi service url.restauthenabled
: Gluster REST service authentication boolean that enables authentication to the REST server. If this value is ‘true’, restuser
and restuserkey
or secretNamespace
+ secretName
have to be filled. This option is deprecated, authentication is enabled when any of restuser
, restuserkey
, secretName
or secretNamespace
is specified.restuser
: Gluster REST service/Heketi user who has access to create volumes in the Gluster Trusted Pool.restuserkey
: Gluster REST service/Heketi user’s password which will be used for authentication to the REST server. This parameter is deprecated in favor of secretNamespace
+ secretName
.secretNamespace
, secretName
: Identification of Secret instance that contains user password to use when talking to Gluster REST service. These parameters are optional, empty password will be used when both secretNamespace
and secretName
are omitted. The provided secret must have type “kubernetes.io/glusterfs”, e.g. created in this way:
$ kubectl create secret generic heketi-secret --type="kubernetes.io/glusterfs" --from-literal=key='opensesame' --namespace=default
Example of a secret can be found in glusterfs-provisioning-secret.yaml.clusterid
: 630372ccdc720a92c681fb928f27b53f
is the ID of the cluster which will be used by Heketi when provisioning the volume. It can also be a list of clusterids, for ex:
“8452344e2becec931ece4e33c4674e4e,42982310de6c63381718ccfa6d8cf397”. This is an optional parameter.gidMin
, gidMax
: The minimum and maximum value of GID range for the storage class. A unique value (GID) in this range ( gidMin-gidMax ) will be used for dynamically provisioned volumes. These are optional values. If not specified, the volume will be provisioned with a value between 2000-2147483647 which are defaults for gidMin and gidMax respectively.volumetype
: The volume type and its parameters can be configured with this optional value. If the volume type is not mentioned, it’s up to the provisioner to decide the volume type.
For example:
‘Replica volume’:
volumetype: replicate:3
where ‘3’ is replica count.
‘Disperse/EC volume’:
volumetype: disperse:4:2
where ‘4’ is data and ‘2’ is the redundancy count.
‘Distribute volume’:
volumetype: none
For available volume types and administration options, refer to the Administration Guide.
For further reference information, see How to configure Heketi.
When persistent volumes are dynamically provisioned, the Gluster plugin automatically creates an endpoint and a headless service in the name gluster-dynamic-<claimname>
. The dynamic endpoint and service are automatically deleted when the persistent volume claim is deleted.
kind: StorageClass
apiVersion: storage.k8s.io/v1
metadata:
name: gold
provisioner: kubernetes.io/cinder
parameters:
type: fast
availability: nova
type
: VolumeType created in Cinder. Default is empty.availability
: Availability Zone. If not specified, volumes are generally round-robin-ed across all active zones where Kubernetes cluster has a node.yaml
kind: StorageClass
apiVersion: storage.k8s.io/v1
metadata:
name: fast
provisioner: kubernetes.io/vsphere-volume
parameters:
diskformat: zeroedthick
diskformat
: thin
, zeroedthick
and eagerzeroedthick
. Default: "thin"
.yaml
kind: StorageClass
apiVersion: storage.k8s.io/v1beta1
metadata:
name: fast
provisioner: kubernetes.io/vsphere-volume
parameters:
diskformat: zeroedthick
datastore: VSANDatastore
diskformat
: thin
, zeroedthick
and eagerzeroedthick
. Default: "thin"
.datastore
: The user can also specify the datastore in the Storageclass. The volume will be created on the datastore specified in the storage class which in this case is VSANDatastore
. This field is optional. If not specified as in previous YAML description, the volume will be created on the datastore specified in the vsphere config file used to initialize the vSphere Cloud Provider.yaml
kind: StorageClass
apiVersion: storage.k8s.io/v1beta1
metadata:
name: vsan-policy-fast
provisioner: kubernetes.io/vsphere-volume
parameters:
diskformat: thin
hostFailuresToTolerate: "1"
diskStripes: "2"
cacheReservation: "20"
datastore: VSANDatastore
As described in official documentation, VSAN exposes multiple storage capabilities. The below table lists VSAN storage capabilities that are currently supported by vSphere Cloud Provider.
Storage Capability Name | Description |
---|---|
cacheReservation | Flash read cache reservation |
diskStripes | Number of disk stripes per object |
forceProvisioning | Force provisioning |
hostFailuresToTolerate | Number of failures to tolerate |
iopsLimit | IOPS limit for object |
objectSpaceReservation | Object space reservation |
vSphere Infrastructure(VI) administrator can specify storage requirements for applications in terms of storage capabilities while creating a storage class inside Kubernetes. Please note that while creating a StorageClass, administrator should specify storage capability names used in the table above as these names might differ from the ones used by VSAN. For example - Number of disk stripes per object is referred to as stripeWidth in VSAN documentation however vSphere Cloud Provider uses a friendly name diskStripes.
You can see vSphere example for more details.
apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
name: fast
provisioner: kubernetes.io/rbd
parameters:
monitors: 10.16.153.105:6789
adminId: kube
adminSecretName: ceph-secret
adminSecretNamespace: kube-system
pool: kube
userId: kube
userSecretName: ceph-secret-user
monitors
: Ceph monitors, comma delimited. This parameter is required.adminId
: Ceph client ID that is capable of creating images in the pool. Default is “admin”.adminSecretNamespace
: The namespace for adminSecret
. Default is “default”.adminSecret
: Secret Name for adminId
. This parameter is required. The provided secret must have type “kubernetes.io/rbd”.pool
: Ceph RBD pool. Default is “rbd”.userId
: Ceph client ID that is used to map the RBD image. Default is the same as adminId
.userSecretName
: The name of Ceph Secret for userId
to map RBD image. It must exist in the same namespace as PVCs. This parameter is required. The provided secret must have type “kubernetes.io/rbd”, e.g. created in this way:
$ kubectl create secret generic ceph-secret --type="kubernetes.io/rbd" --from-literal=key='QVFEQ1pMdFhPUnQrSmhBQUFYaERWNHJsZ3BsMmNjcDR6RFZST0E9PQ==' --namespace=kube-system
apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
name: slow
provisioner: kubernetes.io/quobyte
parameters:
quobyteAPIServer: "http://138.68.74.142:7860"
registry: "138.68.74.142:7861"
adminSecretName: "quobyte-admin-secret"
adminSecretNamespace: "kube-system"
user: "root"
group: "root"
quobyteConfig: "BASE"
quobyteTenant: "DEFAULT"
quobyteAPIServer
: API Server of Quobyte in the format http(s)://api-server:7860
registry
: Quobyte registry to use to mount the volume. You can specify the registry as <host>:<port>
pair or if you want to specify multiple registries you just have to put a comma between them e.q. <host1>:<port>,<host2>:<port>,<host3>:<port>
. The host can be an IP address or if you have a working DNS you can also provide the DNS names.adminSecretNamespace
: The namespace for adminSecretName
. Default is “default”.adminSecretName
: secret that holds information about the Quobyte user and the password to authenticate against the API server. The provided secret must have type “kubernetes.io/quobyte”, e.g. created in this way:
$ kubectl create secret generic quobyte-admin-secret --type="kubernetes.io/quobyte" --from-literal=key='opensesame' --namespace=kube-system
user
: maps all access to this user. Default is “root”.group
: maps all access to this group. Default is “nfsnobody”.quobyteConfig
: use the specified configuration to create the volume. You can create a new configuration or modify an existing one with the Web console or the quobyte CLI. Default is “BASE”.quobyteTenant
: use the specified tenant ID to create/delete the volume. This Quobyte tenant has to be already present in Quobyte. Default is “DEFAULT”.kind: StorageClass
apiVersion: storage.k8s.io/v1
metadata:
name: slow
provisioner: kubernetes.io/azure-disk
parameters:
skuName: Standard_LRS
location: eastus
storageAccount: azure_storage_account_name
skuName
: Azure storage account Sku tier. Default is empty.location
: Azure storage account location. Default is empty.storageAccount
: Azure storage account name. If storage account is not provided, all storage accounts associated with the resource group are searched to find one that matches skuName
and location
. If storage account is provided, it must reside in the same resource group as the cluster, and skuName
and location
are ignored.kind: StorageClass
apiVersion: storage.k8s.io/v1
metadata:
name: portworx-io-priority-high
provisioner: kubernetes.io/portworx-volume
parameters:
repl: "1"
snap_interval: "70"
io_priority: "high"
fs
: filesystem to be laid out: [none/xfs/ext4] (default: ext4
).block_size
: block size in Kbytes (default: 32
).repl
: number of synchronous replicas to be provided in the form of replication factor [1..3] (default: 1
) A string is expected here i.e."1"
and not 1
.io_priority
: determines whether the volume will be created from higher performance or a lower priority storage [high/medium/low] (default: low
).snap_interval
: clock/time interval in minutes for when to trigger snapshots. Snapshots are incremental based on difference with the prior snapshot, 0 disables snaps (default: 0
). A string is expected here i.e. "70"
and not 70
.aggregation_level
: specifies the number of chunks the volume would be distributed into, 0 indicates a non-aggregated volume (default: 0
). A string is expected here i.e. "0"
and not 0
ephemeral
: specifies whether the volume should be cleaned-up after unmount or should be persistent. emptyDir
use case can set this value to true and persistent volumes
use case such as for databases like Cassandra should set to false, [true/false] (default false
). A string is expected here i.e. "true"
and not true
.kind: StorageClass
apiVersion: storage.k8s.io/v1
metadata:
name: slow
provisioner: kubernetes.io/scaleio
parameters:
gateway: https://192.168.99.200:443/api
system: scaleio
protectionDomain: default
storagePool: default
storageMode: ThinProvisionned
secretRef: sio-secret
readOnly: false
fsType: xfs
provisioner
: attribute is set to kubernetes.io/scaleio
gateway
: address to a ScaleIO API gateway (required)system
: the name of the ScaleIO system (required)protectionDomain
: the name of the ScaleIO protection domainstoragePool
: the name of the volume storage poolstorageMode
: the storage provision mode: ThinProvisionned
(default) or ThickProvisionned
secretRef
: reference to a configuered Secret object (required, see detail below)readOnly
: specifies the access mode to the mounted volumefsType
: the file system to use for the volumeThe ScaleIO Kubernetes volume plugin requires a configuered Secret object.
The secret must be created with type kubernetes.io/scaleio
and use the same namespace value as that of the PVC where it is referenced
as shown in the following command:
$> kubectl create secret generic sio-secret --type="kubernetes.io/scaleio" --from-literal=username=sioadmin --from-literal=password=d2NABDNjMA== --namespace=default
If you’re writing configuration templates or examples that run on a wide range of clusters and need persistent storage, we recommend that you use the following pattern:
volume.beta.kubernetes.io/storage-class
annotation of the PVC.
This will cause the PVC to match the right storage class if the cluster has StorageClasses enabled by the admin.volume.alpha.kubernetes.io/storage-class: default
annotation on the PVC.
alpha
in the name, the code behind this annotation has beta
level support.volume.beta.kubernetes.io/storage-class:
with any value including the empty string since it will prevent DefaultStorageClass admission controller
from running if enabled.DefaultStorageClass
enabled, and to have some form of storage available. However, there may not be any
storage class names which work on all clusters, so continue to not set one by default.
At some point, the alpha annotation will cease to have meaning, but the unset storageClass
field on the PVC
will have the desired effect.