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Zh translation: /docs/concepts/storage/volume-snapshots.md (#18568)

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* zh-trans: /docs/concepts/storage/volume-snapshots.md
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@@ -7,10 +7,12 @@ weight: 20
<!--
---
reviewers:
- jsafrane
- saad-ali
- thockin
- msau42
- jingxu97
- xing-yang
- yuxiangqian
title: Volume Snapshots
content_template: templates/concept
weight: 20
@@ -19,23 +21,22 @@ weight: 20
{{% capture overview %}}
{{< feature-state for_k8s_version="v1.12" state="alpha" >}}
<!--
This document describes the current state of `VolumeSnapshots` in Kubernetes. Familiarity with [persistent volumes](/docs/concepts/storage/persistent-volumes/) is suggested.
-->
{{< feature-state for_k8s_version="1.17" state="beta" >}}
本文档描述 Kubernetes 中 `VolumeSnapshots` 的当前状态。建议先熟悉[持久卷](/docs/concepts/storage/persistent-volumes/)。
<!--
In Kubernetes, a _VolumeSnapshot_ represents a snapshot of a volume on a storage system. This document assumes that you are already familiar with Kubernetes [persistent volumes](/docs/concepts/storage/persistent-volumes/).
-->
在 Kubernetes 中，卷快照是一个存储系统上卷的快照，本文假设你已经熟悉了 Kubernetes 的 [持久卷](/docs/concepts/storage/persistent-volumes/)。
{{% /capture %}}
{{% capture body %}}
<!--
## Introduction
-->
## 介绍
## 介绍 {#introduction}
<!--
Similar to how API resources `PersistentVolume` and `PersistentVolumeClaim` are used to provision volumes for users and administrators, `VolumeSnapshotContent` and `VolumeSnapshot` API resources are provided to create volume snapshots for users and administrators.
@@ -45,7 +46,7 @@ Similar to how API resources `PersistentVolume` and `PersistentVolumeClaim` are
<!--
A `VolumeSnapshotContent` is a snapshot taken from a volume in the cluster that has been provisioned by an administrator. It is a resource in the cluster just like a PersistentVolume is a cluster resource.
-->
`VolumeSnapshotContent` 是从管理员已提供的集群中的卷获取的快照。就像持久卷是集群的资源一样，它也是集群中的资源。
`VolumeSnapshotContent` 是一种快照，从管理员已提供的集群中的卷获取。就像持久卷是集群的资源一样，它也是集群中的资源。
<!--
A `VolumeSnapshot` is a request for snapshot of a volume by a user. It is similar to a PersistentVolumeClaim.
@@ -53,12 +54,9 @@ A `VolumeSnapshot` is a request for snapshot of a volume by a user. It is simila
`VolumeSnapshot` 是用户对于卷的快照的请求。它类似于持久卷声明。
<!--
While `VolumeSnapshots` allow a user to consume abstract storage resources, cluster administrators
need to be able to offer a variety of `VolumeSnapshotContents` without exposing
users to the details of how those volume snapshots should be provisioned. For these needs
there is the `VolumeSnapshotClass` resource.
`VolumeSnapshotClass` allows you to specify different attributes belonging to a `VolumeSnapshot`. These attibutes may differ among snapshots taken from the same volume on the storage system and therefore cannot be expressed by using the same `StorageClass` of a `PersistentVolumeClaim`.
-->
`VolumeSnapshots` 允许用户消费抽象的存储资源，集群管理员需要能够提供多种 `VolumeSnapshotContents`，又不会向用户暴露这些应该供应的卷快照的细节。为了实现这些需求，就需要 `VolumeSnapshotClass` 资源。
`VolumeSnapshotClass` 允许指定属于 `VolumeSnapshot` 的不同属性。从存储系统上相同卷上获取的不同快照，这些参数可能会不一样，因此不能用一个 `PersistentVolumeClaim` 的相同 `StorageClass` 来指卷快照。
<!--
Users need to be aware of the following when using this feature:
@@ -66,178 +64,192 @@ Users need to be aware of the following when using this feature:
当使用该功能时，用户需要注意以下几点：
<!--
* API Objects `VolumeSnapshot`, `VolumeSnapshotContent`, and `VolumeSnapshotClass` are CRDs, not part of the core API.
* API Objects `VolumeSnapshot`, `VolumeSnapshotContent`, and `VolumeSnapshotClass` are {{< glossary_tooltip term_id="CustomResourceDefinition" text="CRDs" >}}, not part of the core API.
* `VolumeSnapshot` support is only available for CSI drivers.
* As part of the deployment process, the Kubernetes team provides a sidecar helper container for the snapshot controller called `external-snapshotter`. It watches `VolumeSnapshot` objects and triggers `CreateSnapshot` and `DeleteSnapshot` operations against a CSI endpoint.
* CSI drivers may or may not have implemented the volume snapshot functionality. The CSI drivers that have provided support for volume snapshot will likely use `external-snapshotter`.
* The CSI drivers that support volume snapshot will automatically install CRDs defined for the volume snapshots.
* As part of the deployment process in the beta version of `VolumeSnapshot`, the Kubernetes team provides a snapshot controller to be deployed into the control plane, and a sidecar helper container called csi-snapshotter to be deployed together with the CSI driver. The snapshot controller watches `VolumeSnapshot` and `VolumeSnapshotContent` objects and is responsible for the creation and deletion of `VolumeSnapshotContent` object in dynamic provisioning. The sidecar csi-snapshotter watches `VolumeSnapshotContent` objects and triggers `CreateSnapshot` and `DeleteSnapshot` operations against a CSI endpoint.
* CSI drivers may or may not have implemented the volume snapshot functionality. The CSI drivers that have provided support for volume snapshot will likely use the csi-snapshotter. See [CSI Driver documentation](https://kubernetes-csi.github.io/docs/) for details.
* The CRDs and snapshot controller installations are the responsibility of the Kubernetes distribution.
-->
* API 对象 `VolumeSnapshot`，`VolumeSnapshotContent` 和 `VolumeSnapshotClass` 是 CRD，不是核心 API 的部分。
* API 对象 `VolumeSnapshot`，`VolumeSnapshotContent` 和 `VolumeSnapshotClass` 是 {{< glossary_tooltip term_id="CustomResourceDefinition" text="CRDs" >}}，不是核心 API 的部分。
* `VolumeSnapshot` 支持仅可用于 CSI 驱动。
* 作为部署过程的一部分，Kubernetes 团队为快照控制器提供了一个名为 `external-snapshotter` 的 sidecar 帮助容器。它监视 `VolumeSnapshot` 对象然后向 CSI 端点触发 `CreateSnapshot` 和 `DeleteSnapshot` 操作。
* CSI 驱动可能实现，也可能没有实现卷快照功能。CSI 驱动可能会使用 `external-snapshotter` 来提供对卷快照的支持。
* 支持卷快照的 CSI 驱动将自动安装 用于定义卷快照定义的 CRD。
* 作为 beta 版本 `VolumeSnapshot` 部署过程的一部分，Kubernetes 团队提供了一个部署于控制平面的快照控制器，并且提供了一个叫做 `csi-snapshotter` 的 sidecar 帮助容器，它和 CSI 驱动程序部署在一起。快照控制器监视 `VolumeSnapshot` 和 `VolumeSnapshotContent` 对象，并且负责动态的创建和删除 `VolumeSnapshotContent` 对象。sidecar csi-snapshotter 监视 `VolumeSnapshotContent` 对象，并且触发针对 CSI 端点的 `CreateSnapshot` 和 `DeleteSnapshot` 的操作。
* CSI 驱动可能实现，也可能没有实现卷快照功能。CSI 驱动可能会使用 csi-snapshotter 来提供对卷快照的支持。详见 [CSI 驱动程序文档](https://kubernetes-csi.github.io/docs/)
* Kubernetes 负责 CRDs 和快照控制器的安装。
<!--
## Lifecycle of a volume snapshot and volume snapshot content
-->
## 卷快照和卷快照内容的生命周期
<!--
`VolumeSnapshotContents` are resources in the cluster. `VolumeSnapshots` are requests for those resources. The interaction between `VolumeSnapshotContents` and `VolumeSnapshots` follow this lifecycle:
-->
## 卷快照和卷快照内容的生命周期 {#lifecycle-of-a-volume-snapshot-and-volume-snapshot-content}
`VolumeSnapshotContents` 是集群中的资源。`VolumeSnapshots` 是对于这些资源的请求。`VolumeSnapshotContents` 和 `VolumeSnapshots` 之间的交互遵循以下生命周期：
<!--
### Provisioning Volume Snapshot
There are two ways snapshots may be provisioned: pre-provisioned or dynamically provisioned.
-->
### 供应卷快照
### 供应卷快照 {#provisioning-volume-snapshot}
快照可以通过两种方式进行配置：预配置或动态配置。
<!--
There are two ways snapshots may be provisioned: statically or dynamically.
#### Pre-provisioned {#static}
A cluster administrator creates a number of `VolumeSnapshotContents`. They carry the details of the real volume snapshot on the storage system which is available for use by cluster users. They exist in the Kubernetes API and are available for consumption.
-->
快照可以通过两种方式进行供应：静态或动态。
<!--
#### Static
-->
#### 静态的
<!--
A cluster administrator creates a number of `VolumeSnapshotContents`. 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.
-->
集群管理员创建多个 `VolumeSnapshotContents`。它们带有实际存储的详细信息，可以供集群用户使用。它们存在于 Kubernetes API 中，并且能够被使用。
#### 预配置 {#static}
集群管理员创建多个 `VolumeSnapshotContents`。它们带有存储系统上实际卷快照的详细信息，可以供集群用户使用。它们存在于 Kubernetes API 中，并且能够被使用。
<!--
#### Dynamic
Instead of using a pre-existing snapshot, you can request that a snapshot to be dynamically taken from a PersistentVolumeClaim. The [VolumeSnapshotClass](/docs/concepts/storage/volume-snapshot-classes/) specifies storage provider-specific parameters to use when taking a snapshot.
-->
#### 动态的
<!--
When none of the static `VolumeSnapshotContents` the administrator created matches a user's `VolumeSnapshot`,
the cluster may try to dynamically provision a volume snapshot specially for the `VolumeSnapshot` object.
This provisioning is based on `VolumeSnapshotClasses`: the `VolumeSnapshot` must request a
[volume snapshot class](/docs/concepts/storage/volume-snapshot-classes/) and
the administrator must have created and configured that class in order for dynamic
provisioning to occur.
-->
当管理员创建的静态 `VolumeSnapshotContents` 都不能匹配用户的 `VolumeSnapshot`，集群可能会尝试专门为 `VolumeSnapshot` 对象供应一个卷快照。此供应基于 `VolumeSnapshotClasses`：`VolumeSnapshot` 必须请求[卷快照类](/docs/concepts/storage/volume-snapshot-classes/)并且管理员必须已经创建并配置了该类，才能进行动态供应。
#### 动态的 {#dynamic}
可以从一个 `PersistentVolumeClaim` 申请动态的获取一个快照，而不用使用已经存在的快照。在使用快照时，[卷快照类](/docs/concepts/storage/volume-snapshot-classes/)指定确切的存储提供者参数。
<!--
### Binding
The snapshot controller handles the binding of a `VolumeSnapshot` object with an appropriate `VolumeSnapshotContent` object, in both pre-provisioned and dynamically provisioned scenarios. The binding is a one-to-one mapping.
-->
### 绑定
### 绑定 {#binding}
在预配置和动态配置场景下，快照控制器处理绑定 `VolumeSnapshot` 对象和其合适的 `VolumeSnapshotContent` 对象。绑定关系是一对一的。
<!--
A user creates, or has already created in the case of dynamic provisioning, a `VolumeSnapshot` with a specific amount of storage requested and with certain access modes. A control loop watches for new VolumeSnapshots, finds a matching VolumeSnapshotContent (if possible), and binds them together. If a VolumeSnapshotContent was dynamically provisioned for a new VolumeSnapshot, the loop will always bind that VolumeSnapshotContent to the VolumeSnapshot. Once bound, `VolumeSnapshot` binds are exclusive, regardless of how they were bound. A VolumeSnapshot to VolumeSnapshotContent binding is a one-to-one mapping.
In the case of pre-provisioned binding, the VolumeSnapshot will remain unbound until the requested VolumeSnapshotContent object is created.
-->
用户创建，或在动态供应场景下已经创建了的 `VolumeSnapshot` 具有特定数量的存储请求和特定的访问模式。一个控制循环监视新的 VolumeSnapshots，找到匹配的 VolumeSnapshotContent（如果可能），并把它们绑定到一起。如果 VolumeSnapshotContent 是给动态供应给一个新的VolumeSnapshot，循环将依然绑定 VolumeSnapshotContent 到 VolumeSnapshot。一旦绑定，无论是如何绑定的，`VolumeSnapshot` 绑定都是排他的。VolumeSnapshot 到 VolumeSnapshotContent 的绑定是一对一的映射。
在预配置快照绑定场景下，`VolumeSnapshotContent` 对象创建之后，才会和 `VolumeSnapshot` 进行绑定。
<!--
VolumeSnapshots will remain unbound indefinitely if a matching VolumeSnapshotContent does not exist. VolumeSnapshots will be bound as matching VolumeSnapshotContents become available.
-->
如果不存在匹配的 VolumeSnapshotContent，VolumeSnapshots 将永远保持未绑定状态。当匹配的 VolumeSnapshotContents 可用时，将绑定 VolumeSnapshots。
### Persistent Volume Claim as Snapshot Source Protection
<!--
### Persistent Volume Claim in Use Protection
-->
### 使用保护的持久性卷声明
<!--
The purpose of the Persistent Volume Claim Object in Use Protection feature is to ensure that in-use PVC API objects are not removed from the system (as this may result in data loss).
The purpose of this protection is to ensure that in-use PersistentVolumeClaim API objects are not removed from the system while a snapshot is being taken from it (as this may result in data loss).
-->
使用保护的持久性卷声明功能的目的是确保使用中的 PVC API 对象不会从系统中被删除（因为这可能会导致数据丢失）。
### 快照源的持久性卷声明保护
这种保护的目的是确保当从 `PersistentVolumeClaim` API 对象中做快照的时候，它不会被从系统中删除（因为这可能会导致数据丢失）。
<!--
If a PVC is in active use by a snapshot as a source to create the snapshot, the PVC is in-use. If a user deletes a PVC API object in active use as a snapshot source, the PVC object is not removed immediately. Instead, removal of the PVC object is postponed until the PVC is no longer actively used by any snapshots. A PVC is no longer used as a snapshot source when `ReadyToUse` of the snapshot `Status` becomes `true`.
While a snapshot is being taken of a PersistentVolumeClaim, that PersistentVolumeClaim is in-use. If you delete a PersistentVolumeClaim API object in active use as a snapshot source, the PersistentVolumeClaim object is not removed immediately. Instead, removal of the PersistentVolumeClaim object is postponed until the snapshot is readyToUse or aborted.
-->
如果一个 PVC 正在被快照用来作为源进行快照创建，则该 PVC 是使用中的。如果用户删除正作为快照源的 PVC API 对象，则 PVC 对象不会立即被删除掉。相反，PVC 对象的删除将推迟到任何快照不在主动使用它为止。当快照的 `Status` 中的 `ReadyToUse`值为 `true` 时，PVC 将不再用作快照源。
当从 `PersistentVolumeClaim` 中生成快照时，`PersistentVolumeClaim` 就在被使用了。如果删除一个作为快照源的 `PersistentVolumeClaim` 对象，这个 `PersistentVolumeClaim` 对象不会立即被删除的。相反，在快照可以被使用或者被放弃之后，才会执行删除 `PersistentVolumeClaim` 对象的动作。
<!--
### Delete
Deletion is triggered by deleting the `VolumeSnapshot` object, and the `DeletionPolicy` will be followed. If the `DeletionPolicy` is `Delete`, then the underlying storage snapshot will be deleted along with the `VolumeSnapshotContent` object. If the `DeletionPolicy` is `Retain`, then both the underlying snapshot and `VolumeSnapshotContent` remain.
-->
### 删除
### 删除 {#delete}
删除 `VolumeSnapshot` 对象触发删除 `VolumeSnapshotContent` 操作，并且 `DeletionPolicy` 会紧跟着执行。如果 `DeletionPolicy` 是 `Delete`，那么底层存储快照会和 `VolumeSnapshotContent` 一起被删除。如果 `DeletionPolicy` 是 `Retain`，那么底层快照和 `VolumeSnapshotContent` 都会被保留。
<!--
Deletion removes both the `VolumeSnapshotContent` object from the Kubernetes API, as well as the associated storage asset in the external infrastructure.
-->
删除操作会从 Kubernetes API 中删除 `VolumeSnapshotContent` 对象，同时删除它在外部基础架构中关联存储资产。
<!--
## Volume Snapshot Contents
-->
## 卷快照内容
<!--
Each VolumeSnapshotContent contains a spec, which is the specification of the volume snapshot.
-->
每个 VolumeSnapshotContent 包含一个 spec，用来表示卷快照的规格。
```yaml
apiVersion: snapshot.storage.k8s.io/v1alpha1
kind: VolumeSnapshotContent
metadata:
name: new-snapshot-content-test
spec:
snapshotClassName: csi-hostpath-snapclass
source:
name: pvc-test
kind: PersistentVolumeClaim
volumeSnapshotSource:
csiVolumeSnapshotSource:
creationTime: 1535478900692119403
driver: csi-hostpath
restoreSize: 10Gi
snapshotHandle: 7bdd0de3-aaeb-11e8-9aae-0242ac110002
```
<!--
### Class
-->
### 类
<!--
A VolumeSnapshotContent can have a class, which is specified by setting the
`snapshotClassName` attribute to the name of a
[VolumeSnapshotClass](/docs/concepts/storage/volume-snapshot-classes/).
A VolumeSnapshotContent of a particular class can only be bound to VolumeSnapshots requesting
that class. A VolumeSnapshotContent with no `snapshotClassName` has no class and can only be bound
to VolumeSnapshots that request no particular class.
-->
VolumeSnapshotContent 可以具有一个类，该类通过设置 `snapshotClassName` 属性为 [VolumeSnapshotClass](/docs/concepts/storage/volume-snapshot-classes/) 的名称来指定。一个特定类的 VolumeSnapshotContent 只能够绑定到请求该类的 VolumeSnapshots。没有 `snapshotClassName` 的 VolumeSnapshotContent 没有类，并且只能绑定到不要求特定类的 VolumeSnapshots。
## VolumeSnapshots
<!--
Each VolumeSnapshot contains a spec and a status, which is the specification and status of the volume snapshot.
Each VolumeSnapshot contains a spec and a status.
-->
每个 VolumeSnapshot 对象包含 spec 和 status，用来表示卷快照的规格和状态。
## 卷快照 {#volume-snapshots}
每个 `VolumeSnapshot` 包含一个 spec 和一个状态。
```yaml
apiVersion: snapshot.storage.k8s.io/v1alpha1
apiVersion: snapshot.storage.k8s.io/v1beta1
kind: VolumeSnapshot
metadata:
name: new-snapshot-test
spec:
snapshotClassName: csi-hostpath-snapclass
volumeSnapshotClassName: csi-hostpath-snapclass
source:
name: pvc-test
kind: PersistentVolumeClaim
persistentVolumeClaimName: pvc-test
```
<!--
### Class
-->
### 类
`persistentVolumeClaimName` is the name of the PersistentVolumeClaim data source for the snapshot. This field is required for dynamically provisioning a snapshot.
<!--
A volume snapshot can request a particular class by specifying the name of a
[VolumeSnapshotClass](/docs/concepts/storage/volume-snapshot-classes/)
using the attribute `snapshotClassName`.
Only VolumeSnapshotContents of the requested class, ones with the same `snapshotClassName`
as the VolumeSnapshot, can be bound to the VolumeSnapshot.
using the attribute `volumeSnapshotClassName`. If nothing is set, then the default class is used if available.
-->
通过使用 `snapshotClassName` 属性来指定 [VolumeSnapshotClass](/docs/concepts/storage/volume-snapshot-classes/) 的名称，卷快照可以请求特定的类。
只有所请求类（与 VolumeSnapshot 有相同的 `snapshotClassName`）的 VolumeSnapshotContents 才可以绑定到 VolumeSnapshot。
`persistentVolumeClaimName` 是 `PersistentVolumeClaim` 数据源对快照的名称。这个字段是动态配置快照中的必填字段。
卷快照可以通过指定 [VolumeSnapshotClass](/docs/concepts/storage/volume-snapshot-classes/) 使用 `volumeSnapshotClassName` 属性来请求特定类。如果没有设置，那么使用默认类（如果有）。
<!--
For pre-provisioned snapshots, you need to specify a `volumeSnapshotContentName` as the source for the snapshot as shown in the following example. The `volumeSnapshotContentName` source field is required for pre-provisioned snapshots.
-->
对于预配置的快照，像下面的例子一样，需要给快照指定 `volumeSnapshotContentName` 来作为源。对于预配置的快照 `source` 中的`volumeSnapshotContentName` 字段是必填的
```
apiVersion: snapshot.storage.k8s.io/v1beta1
kind: VolumeSnapshot
metadata:
name: test-snapshot
spec:
source:
volumeSnapshotContentName: test-content
```
<!--
## Volume Snapshot Contents
Each VolumeSnapshot contains a spec and a status, which is the specification and status of the volume snapshot.
Each VolumeSnapshotContent contains a spec and status. In dynamic provisioning, the snapshot common controller creates `VolumeSnapshotContent` objects. Here is an example:
-->
每个 VolumeSnapshotContent 对象包含 spec 和 status。在动态配置时，快照通用控制器创建 `VolumeSnapshotContent` 对象。下面是例子：
```yaml
apiVersion: snapshot.storage.k8s.io/v1beta1
kind: VolumeSnapshotContent
metadata:
name: snapcontent-72d9a349-aacd-42d2-a240-d775650d2455
spec:
deletionPolicy: Delete
driver: hostpath.csi.k8s.io
source:
volumeHandle: ee0cfb94-f8d4-11e9-b2d8-0242ac110002
volumeSnapshotClassName: csi-hostpath-snapclass
volumeSnapshotRef:
name: new-snapshot-test
namespace: default
uid: 72d9a349-aacd-42d2-a240-d775650d2455
```
<!--
`volumeHandle` is the unique identifier of the volume created on the storage backend and returned by the CSI driver during the volume creation. This field is required for dynamically provisioning a snapshot. It specifies the volume source of the snapshot.
For pre-provisioned snapshots, you (as cluster administrator) are responsible for creating the `VolumeSnapshotContent` object as follows.
-->
`volumeHandle` 是存储后端创建卷的唯一标识符，在卷创建期间由 CSI 驱动程序返回。动态设置快照需要此字段。它指出了快照的卷源。
对于预配置快照，你（作为集群管理员）要按如下命令来创建 `VolumeSnapshotContent` 对象。
```yaml
apiVersion: snapshot.storage.k8s.io/v1beta1
kind: VolumeSnapshotContent
metadata:
name: new-snapshot-content-test
spec:
deletionPolicy: Delete
driver: hostpath.csi.k8s.io
source:
snapshotHandle: 7bdd0de3-aaeb-11e8-9aae-0242ac110002
volumeSnapshotRef:
name: new-snapshot-test
namespace: default
```
<!--
`snapshotHandle` is the unique identifier of the volume snapshot created on the storage backend. This field is required for the pre-provisioned snapshots. It specifies the CSI snapshot id on the storage system that this `VolumeSnapshotContent` represents.
-->
`snapshotHandle` 是存储后端创建卷的唯一标识符。对于预设置快照，这个字段是必须的。它指定此 `VolumeSnapshotContent` 表示的存储系统上的 CSI 快照 id。
<!--
## Provisioning Volumes from Snapshots
@@ -248,7 +260,7 @@ as the VolumeSnapshot, can be bound to the VolumeSnapshot.
You can provision a new volume, pre-populated with data from a snapshot, by using
the *dataSource* field in the `PersistentVolumeClaim` object.
-->
你可以供应一个新卷，该卷预填充了快照中的数据，在 `持久卷声明` 对象中使用 *dataSource* 字段。
你可以配置一个新卷，该卷预填充了快照中的数据，在 `持久卷声明` 对象中使用 *dataSource* 字段。
<!--
For more details, see