whentimeslows/website
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

Split persistent volume concept article (#6215)

Browse Source
This commit is contained in:
Qiming
2017-11-17 10:45:35 +08:00
committed by Zach Corleissen
parent 53bf960e2a
commit 5e19e823b5
4 changed files with 687 additions and 493 deletions
Download Patch File Download Diff File Expand all files Collapse all files
docs/concepts/storage/storage-classes.md
+636
View File
@@ -0,0 +1,636 @@
---
approvers:
- jsafrane
- mikedanese
- saad-ali
- thockin
title: Storage Classes
---
This document describes the concept of `StorageClass` in Kubernetes. Familiarity
with [volumes](/docs/concepts/storage/volumes/) and
[persistent volumes](/docs/concepts/storage/persistent-volumes) is suggested.
* TOC
{:toc}
## Introduction
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.
## The StorageClass Resource
Each `StorageClass` contains the fields `provisioner`, `parameters`, and
`reclaimPolicy`, 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](#persistentvolumeclaims)
for details.
```yaml
kind: StorageClass
apiVersion: storage.k8s.io/v1
metadata:
name: standard
provisioner: kubernetes.io/aws-ebs
parameters:
type: gp2
reclaimPolicy: Retain
mountOptions:
- debug
```
### Provisioner
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](#aws) |
| AzureFile | ✓ | [Azure File](#azure-file) |
| AzureDisk | ✓ | [Azure Disk](#azure-disk) |
| CephFS | - | - |
| Cinder | ✓ | [OpenStack Cinder](#openstack-cinder)|
| FC | - | - |
| FlexVolume | - | - |
| Flocker | ✓ | - |
| GCEPersistentDisk | ✓ | [GCE](#gce) |
| Glusterfs | ✓ | [Glusterfs](#glusterfs) |
| iSCSI | - | - |
| PhotonPersistentDisk | ✓ | - |
| Quobyte | ✓ | [Quobyte](#quobyte) |
| NFS | - | - |
| RBD | ✓ | [Ceph RBD](#ceph-rbd) |
| VsphereVolume | ✓ | [vSphere](#vsphere) |
| PortworxVolume | ✓ | [Portworx Volume](#portworx-volume) |
| ScaleIO | ✓ | [ScaleIO](#scaleio) |
| StorageOS | ✓ | [StorageOS](#storageos) |
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](https://git.k8s.io/community/contributors/design-proposals/storage/volume-provisioning.md)
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](https://github.com/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](https://github.com/kubernetes-incubator/external-storage).
There are also cases when 3rd party storage vendors provide their own external
provisioner.
### Reclaim Policy
Persistent Volumes that are dynamically created by a storage class will have the
reclaim policy specified in the `reclaimPolicy` field of the class, which can be
either `Delete` or `Retain`. If no `reclaimPolicy` is specified when a
`StorageClass` object is created, it will default to `Delete`.
Persistent Volumes that are created manually and managed via a storage class will have
whatever reclaim policy they were assigned at creation.
### Mount Options
Persistent Volumes that are dynamically created by a storage class will have the
mount options specified in the `mountOptions` field of the class.
If the volume plugin does not support mount options but mount options are
specified, provisioning will fail. Mount options are not validated on neither
the class nor PV, so mount of the PV will simply fail if one is invalid.
## Parameters
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.
### AWS
```yaml
kind: StorageClass
apiVersion: storage.k8s.io/v1
metadata:
name: slow
provisioner: kubernetes.io/aws-ebs
parameters:
type: io1
zones: us-east-1d, us-east-1c
iopsPerGB: "10"
```
* `type`: `io1`, `gp2`, `sc1`, `st1`. See
[AWS docs](http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/EBSVolumeTypes.html)
for details. Default: `gp2`.
* `zone`: AWS zone. If neither `zone` nor `zones` is specified, volumes are
generally round-robin-ed across all active zones where Kubernetes cluster
has a node. `zone` and `zones` parameters must not be used at the same time.
* `zones`: A comma separated list of AWS zone(s). If neither `zone` nor `zones`
is specified, volumes are generally round-robin-ed across all active zones
where Kubernetes cluster has a node. `zone` and `zones` parameters must not
be used at the same time.
* `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](http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/EBSVolumeTypes.html).
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.
### GCE
```yaml
kind: StorageClass
apiVersion: storage.k8s.io/v1
metadata:
name: slow
provisioner: kubernetes.io/gce-pd
parameters:
type: pd-standard
zones: us-central1-a, us-central1-b
```
* `type`: `pd-standard` or `pd-ssd`. Default: `pd-standard`
* `zone`: GCE zone. If neither `zone` nor `zones` is specified, volumes are
generally round-robin-ed across all active zones where Kubernetes cluster has
a node. `zone` and `zones` parameters must not be used at the same time.
* `zones`: A comma separated list of GCE zone(s). If neither `zone` nor `zones`
is specified, volumes are generally round-robin-ed across all active zones
where Kubernetes cluster has a node. `zone` and `zones` parameters must not
be used at the same time.
### Glusterfs
```yaml
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](https://github.com/kubernetes/examples/tree/master/staging/persistent-volume-provisioning/glusterfs/glusterfs-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 example:
`"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](https://access.redhat.com/documentation/en-US/Red_Hat_Storage/3.1/html/Administration_Guide/part-Overview.html).
For further reference information, see
[How to configure Heketi](https://github.com/heketi/heketi/wiki/Setting-up-the-topology).
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.
### OpenStack Cinder
```yaml
kind: StorageClass
apiVersion: storage.k8s.io/v1
metadata:
name: gold
provisioner: kubernetes.io/cinder
parameters:
type: fast
availability: nova
```
* `type`: [VolumeType](https://docs.openstack.org/user-guide/dashboard-manage-volumes.html)
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.
### vSphere
1. Create a StorageClass with a user specified disk format.
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"`.
2. Create a StorageClass with a disk format on a user specified datastore.
kind: StorageClass
apiVersion: storage.k8s.io/v1
metadata:
name: fast
provisioner: kubernetes.io/vsphere-volume
parameters:
diskformat: zeroedthick
datastore: VSANDatastore
`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 the
datastore is not specified, then the volume will be created on the datastore
specified in the vSphere config file used to initialize the vSphere Cloud
Provider.
3. Storage Policy Management inside kubernetes
* Using existing vCenter SPBM policy
One of the most important features of vSphere for Storage Management is
policy based Management. Storage Policy Based Management (SPBM) is a
storage policy framework that provides a single unified control plane
across a broad range of data services and storage solutions. SPBM enables
vSphere administrators to overcome upfront storage provisioning challenges,
such as capacity planning, differentiated service levels and managing
capacity headroom.
The SPBM policies can be specified in the StorageClass using the
`storagePolicyName` parameter.
* Virtual SAN policy support inside Kubernetes
Vsphere Infrastructure (VI) Admins will have the ability to specify custom
Virtual SAN Storage Capabilities during dynamic volume provisioning. You
can now define storage requirements, such as performance and availability,
in the form of storage capabilities during dynamic volume provisioning.
The storage capability requirements are converted into a Virtual SAN
policy which are then pushed down to the Virtual SAN layer when a
persistent volume (virtual disk) is being created. The virtual disk is
distributed across the Virtual SAN datastore to meet the requirements.
You can see [Storage Policy Based Management for dynamic provisioning of volumes](https://vmware.github.io/vsphere-storage-for-kubernetes/documentation/policy-based-mgmt.html)
for more details on how to use storage policies for persistent volumes
management.
There are few
[vSphere examples](https://github.com/kubernetes/examples/tree/master/staging/volumes/vsphere)
which you try out for persistent volume management inside Kubernetes for vSphere.
### Ceph RBD
```yaml
kind: StorageClass
apiVersion: storage.k8s.io/v1
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
fsType: ext4
imageFormat: "2"
imageFeatures: "layering"
```
* `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
```
* `fsType`: fsType that is supported by kubernetes. Default: `"ext4"`.
* `imageFormat`: Ceph RBD image format, "1" or "2". Default is "1".
* `imageFeatures`: This parameter is optional and should only be used if you
set `imageFormat` to "2". Currently supported features are `layering` only.
Default is "", and no features are turned on.
#### Quobyte
```yaml
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".
### Azure Disk
#### Azure Unmanaged Disk Storage Class
```yaml
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 a storage account is provided,
it must reside in the same resource group as the cluster, and `location` is
ignored. If a storage account is not provided, a new storage account will be
created in the same resource group as the cluster.
#### New Azure Disk Storage Class (starting from v1.7.2)
```yaml
kind: StorageClass
apiVersion: storage.k8s.io/v1
metadata:
name: slow
provisioner: kubernetes.io/azure-disk
parameters:
storageaccounttype: Standard_LRS
kind: Shared
```
* `storageaccounttype`: Azure storage account Sku tier. Default is empty.
* `kind`: Possible values are `shared` (default), `dedicated`, and `managed`.
When `kind` is `shared`, all unmanaged disks are created in a few shared
storage accounts in the same resource group as the cluster. When `kind` is
`dedicated`, a new dedicated storage account will be created for the new
unmanaged disk in the same resource group as the cluster.
- Premium VM can attach both Standard_LRS and Premium_LRS disks, while Standard
VM can only attach Standard_LRS disks.
- Managed VM can only attach managed disks and unmanaged VM can only attach
unmanaged disks.
### Azure File
```yaml
kind: StorageClass
apiVersion: storage.k8s.io/v1
metadata:
name: azurefile
provisioner: kubernetes.io/azure-file
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. Default is empty. If a storage
account is not provided, all storage accounts associated with the resource
group are searched to find one that matches `skuName` and `location`. If a
storage account is provided, it must reside in the same resource group as the
cluster, and `skuName` and `location` are ignored.
During provision, a secret is created for mounting credentials. If the cluster
has enabled both [RBAC](/docs/admin/authorization/rbac/) and
[Controller Roles](/docs/admin/authorization/rbac/#controller-roles), add the
`create` permission of resource `secret` for clusterrole
`system:controller:persistent-volume-binder`.
### Portworx Volume
```yaml
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`.
### ScaleIO
```yaml
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: pd0
storagePool: sp1
storageMode: ThinProvisioned
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 domain (required)
* `storagePool`: the name of the volume storage pool (required)
* `storageMode`: the storage provision mode: `ThinProvisioned` (default) or
`ThickProvisioned`
* `secretRef`: reference to a configured Secret object (required)
* `readOnly`: specifies the access mode to the mounted volume (default false)
* `fsType`: the file system to use for the volume (default ext4)
The ScaleIO Kubernetes volume plugin requires a configured 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:
```shell
kubectl create secret generic sio-secret --type="kubernetes.io/scaleio" \
--from-literal=username=sioadmin --from-literal=password=d2NABDNjMA== \
--namespace=default
```
### StorageOS
```yaml
kind: StorageClass
apiVersion: storage.k8s.io/v1
metadata:
name: fast
provisioner: kubernetes.io/storageos
parameters:
pool: default
description: Kubernetes volume
fsType: ext4
adminSecretNamespace: default
adminSecretName: storageos-secret
```
* `pool`: The name of the StorageOS distributed capacity pool to provision the
volume from. Uses the `default` pool which is normally present if not specified.
* `description`: The description to assign to volumes that were created dynamically.
All volume descriptions will be the same for the storage class, but different
storage classes can be used to allow descriptions for different use cases.
Defaults to `Kubernetes volume`.
* `fsType`: The default filesystem type to request. Note that user-defined rules
within StorageOS may override this value. Defaults to `ext4`.
* `adminSecretNamespace`: The namespace where the API configuration secret is
located. Required if adminSecretName set.
* `adminSecretName`: The name of the secret to use for obtaining the StorageOS
API credentials. If not specified, default values will be attempted.
The StorageOS Kubernetes volume plugin can use a Secret object to specify an
endpoint and credentials to access the StorageOS API. This is only required when
the defaults have been changed.
The secret must be created with type `kubernetes.io/storageos` as shown in the
following command:
```shell
kubectl create secret generic storageos-secret \
--type="kubernetes.io/storageos" \
--from-literal=apiAddress=tcp://localhost:5705 \
--from-literal=apiUsername=storageos \
--from-literal=apiPassword=storageos \
--namespace=default
```
Secrets used for dynamically provisioned volumes may be created in any namespace
and referenced with the `adminSecretNamespace` parameter. Secrets used by
pre-provisioned volumes must be created in the same namespace as the PVC that
references it.