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Backup and Restore Overview

This document describes how to perform backup and restore on the TiDB cluster in Kubernetes. The backup and restore tools used are BR, Dumpling, and TiDB Lightning.

TiDB Operator 1.1 and later versions implement the backup and restore methods using Custom Resource Definition (CRD):

User scenarios

Dumpling is a data export tool that exports data stored in TiDB/MySQL as SQL or CSV data files to get the logic full backup or export. If you need to back up SST files (Key-Value pairs) directly or perform latency-insensitive incremental backup, refer to BR. For real-time incremental backup, refer to TiCDC.

TiDB Lightning is a tool used for fast full data import into a TiDB cluster. TiDB Lightning supports Dumpling or CSV format data source. You can use TiDB Lightning for the following two purposes:

  • Quickly import large amounts of data
  • Restore all backup data

BR is a command-line tool for distributed backup and restore of the TiDB cluster data. Compared with Dumpling and mydumper, BR is more suitable for scenarios of huge data volume. BR only supports TiDB v3.1 and later versions.

Backup CR fields

To back up data for a TiDB cluster in Kubernetes, you can create a Backup Custom Resource (CR) object. For detailed backup process, refer to documents listed in Backup and Restore Overview.

This section introduces the fields in the Backup CR.

General fields

  • .spec.metadata.namespace: The namespace where the Backup CR is located.

  • .spec.tikvGCLifeTime: The temporary tikv_gc_life_time time setting during the backup, which defaults to 72h.

    Before the backup begins, if the tikv_gc_life_time setting in the TiDB cluster is smaller than spec.tikvGCLifeTime set by the user, TiDB Operator adjusts the value of tikv_gc_life_time to the value of spec.tikvGCLifeTime. This operation makes sure that the backup data is not garbage-collected by TiKV.

    After the backup, no matter the backup is successful or not, as long as the previous tikv_gc_life_time value is smaller than .spec.tikvGCLifeTime, TiDB Operator will try to set tikv_gc_life_time to the previous value.

    In extreme cases, if TiDB Operator fails to access the database, TiDB Operator cannot automatically recover the value of tikv_gc_life_time and treats the backup as failed. At this time, you can view tikv_gc_life_time of the current TiDB cluster using the following statement:

    select VARIABLE_NAME, VARIABLE_VALUE from mysql.tidb where VARIABLE_NAME like "tikv_gc_life_time";

    In the output of the command above, if the value of tikv_gc_life_time is still larger than expected (usually 10m), you need to set tikv_gc_life_time back to the previous value manually:

  • .spec.cleanPolicy: The cleaning policy for the backup data when the backup CR is deleted.

    Three clean policies are supported:

    • Retain: Under any circumstances, retain the backup data when deleting the backup CR.

    • Delete: Under any circumstances, delete the backup data when deleting the backup CR.

    • OnFailure: If the backup fails, delete the backup data when deleting the backup CR.

      If this field is not configured, or if you configure a value other than the three policies above, the backup data is retained.

      Note that in v1.1.2 and earlier versions, this field does not exist. The backup data is deleted along with the CR by default. For v1.1.3 or later versions, if you want to keep this earlier behavior, set this field to Delete.

  • .spec.from.host: The address of the TiDB cluster to be backed up, which is the service name of the TiDB cluster to be exported, such as basic-tidb.

  • .spec.from.port: The port of the TiDB cluster to be backed up.

  • .spec.from.user: The accessing user of the TiDB cluster to be backed up.

  • .spec.from.secretName: The secret that contains the password of the .spec.from.user.

  • .spec.from.tlsClientSecretName: The secret of the certificate used during the backup.

    If TLS is enabled for the TiDB cluster, but you do not want to back up data using the ${cluster_name}-cluster-client-secret as described in Enable TLS between TiDB Components, you can use the .spec.from.tlsClient.tlsSecret parameter to specify a secret for the backup. To generate the secret, run the following command:

    kubectl create secret generic ${secret_name} --namespace=${namespace} --from-file=tls.crt=${cert_path} --from-file=tls.key=${key_path} --from-file=ca.crt=${ca_path}
  • .spec.storageClassName: The persistent volume (PV) type specified for the backup operation.

  • .spec.storageSize: The PV size specified for the backup operation (100 Gi by default). This value must be greater than the size of the TiDB cluster to be backed up.

    The PVC name corresponding to the Backup CR of a TiDB cluster is fixed. If the PVC already exists in the cluster namespace and the size is smaller than spec.storageSize, you need to delete this PVC and then run the Backup job.

  • .spec.tableFilter: Specifies tables that match the table filter rules for BR or Dumpling. This field can be ignored by default.

    If the field is not configured, the default value of tableFilter is as follows:

    tableFilter:
    - "*.*"
    - "!/^(mysql|test|INFORMATION_SCHEMA|PERFORMANCE_SCHEMA|METRICS_SCHEMA|INSPECTION_SCHEMA)$/.*"

    If you use BR to perform backup, BR backs up all schemas except the system schema.

    Note:

    To use the table filter to exclude db.table, you need to first add the *.* rule to include all tables. For example:

    tableFilter:
    - "*.*"
    - "!db.table"

BR fields

  • .spec.br.cluster: The name of the cluster to be backed up.
  • .spec.br.clusterNamespace: The namespace of the cluster to be backed up.
  • .spec.br.logLevel: The log level (info by default).
  • .spec.br.statusAddr: The listening address through which BR provides statistics. If not specified, BR does not listen on any status address by default.
  • .spec.br.concurrency: The number of threads used by each TiKV process during backup. Defaults to 4 for backup and 128 for restore.
  • .spec.br.rateLimit: The speed limit, in MB/s. If set to 4, the speed limit is 4 MB/s. The speed limit is not set by default.
  • .spec.br.checksum: Whether to verify the files after the backup is completed. Defaults to true.
  • .spec.br.timeAgo: Backs up the data before timeAgo. If the parameter value is not specified (empty by default), it means backing up the current data. It supports data formats such as "1.5h" and "2h45m". See ParseDuration for more information.
  • .spec.br.sendCredToTikv: Whether the BR process passes its AWS or GCP privileges to the TiKV process. Defaults to true.
  • .spec.br.options: The extra arguments that BR supports. This field is supported since TiDB Operator v1.1.6. It accepts an array of strings and can be used to specify the last backup timestamp --lastbackupts for incremental backup.

S3 storage fields

  • .spec.s3.provider: The supported S3-compatible storage provider. Options are as follows:

    • alibaba: Alibaba Cloud Object Storage System (OSS), formerly Aliyun
    • digitalocean: Digital Ocean Spaces
    • dreamhost: Dreamhost DreamObjects
    • ibmcos: IBM COS S3
    • minio: Minio Object Storage
    • netease: Netease Object Storage (NOS)
    • wasabi: Wasabi Object Storage
    • other: Any other S3 compatible provider
  • spec.s3.region: If you want to use Amazon S3 for backup storage, configure this field as the region where Amazon S3 is located.

  • .spec.s3.bucket: The name of the bucket compatible with S3 storage.

  • .spec.s3.prefix: If you set this field, the value is used to make up the remote storage path s3://${.spec.s3.bucket}/${.spec.s3.prefix}/backupName.

  • .spec.s3.acl: The supported access-control list (ACL) policies.

    Amazon S3 supports the following ACL options:

    • private

    • public-read

    • public-read-write

    • authenticated-read

    • bucket-owner-read

    • bucket-owner-full-control

      If the field is not configured, the policy defaults to private. For more information on the ACL policies, refer to AWS documentation.

  • .spec.s3.storageClass: The supported storage class.

    Amazon S3 supports the following storage class options:

    • STANDARD

    • REDUCED_REDUNDANCY

    • STANDARD_IA

    • ONEZONE_IA

    • GLACIER

    • DEEP_ARCHIVE

      If the field is not configured, the storage class defaults to STANDARD_IA. For more information on storage classes, refer to AWS documentation.

GCS fields

  • .spec.gcs.projectId: The unique identifier of the user project on GCP. To obtain the project ID, refer to GCP documentation.

  • .spec.gcs.bucket: The name of the bucket which stores data.

  • .spec.gcs.prefix: If you set this field, the value is used to make up the path of the remote storage: gcs://${.spec.gcs.bucket}/${.spec.gcs.prefix}/backupName. This field can be ignored.

  • spec.gcs.storageClass: The supported storage class.

    GCS supports the following storage class options:

    • MULTI_REGIONAL

    • REGIONAL

    • NEARLINE

    • COLDLINE

    • DURABLE_REDUCED_AVAILABILITY

      If the field is not configured, the storage class defaults to COLDLINE. For more information on storage classes, refer to GCS documentation.

  • .spec.gcs.objectAcl: The supported object access-control list (ACL) policies.

    GCS supports the following object ACL options:

    • authenticatedRead

    • bucketOwnerFullControl

    • bucketOwnerRead

    • private

    • projectPrivate

    • publicRead

      If the field is not configured, the policy defaults to private. For more information on the ACL policies, refer to GCS documentation.

  • .spec.gcs.bucketAcl: The supported bucket access-control list (ACL) policies.

    GCS supports the following bucket ACL options:

    • authenticatedRead

    • private

    • projectPrivate

    • publicRead

    • publicReadWrite

      If the field is not configured, the policy defaults to private. For more information on the ACL policies, refer to GCS documentation.

Local storage fields

  • .spec.local.prefix: The storage directory of the persistent volumes. If you set this field, the value is used to make up the storage path of the persistent volume: local://${.spec.local.volumeMount.mountPath}/${.spec.local.prefix}/.
  • .spec.local.volume: The persistent volume configuration.
  • .spec.local.volumeMount: The persistent volume mount configuration.

Restore CR fields

To restore data to a TiDB cluster in Kubernetes, you can create a Restore CR object. For detailed restore process, refer to documents listed in Backup and Restore Overview.

This section introduces the fields in the Restore CR.

  • .spec.metadata.namespace: The namespace where the Restore CR is located.

  • .spec.to.host: The address of the TiDB cluster to be restored.

  • .spec.to.port: The port of the TiDB cluster to be restored.

  • .spec.to.user: The accessing user of the TiDB cluster to be restored.

  • .spec.to.secretName: The secret that contains the password of the .spec.to.user.

  • .spec.to.tlsClientSecretName: The secret of the certificate used during the restore.

    If TLS is enabled for the TiDB cluster, but you do not want to restore data using the ${cluster_name}-cluster-client-secret as described in Enable TLS between TiDB Components, you can use the .spec.to.tlsClient.tlsSecret parameter to specify a secret for the restore. To generate the secret, run the following command:

    kubectl create secret generic ${secret_name} --namespace=${namespace} --from-file=tls.crt=${cert_path} --from-file=tls.key=${key_path} --from-file=ca.crt=${ca_path}
  • .spec.storageClassName: The persistent volume (PV) type specified for the restore operation.

  • .spec.storageSize: The PV size specified for the restore operation. This value must be greater than the size of the backup data.

  • .spec.tableFilter: Specifies tables that match the table filter rules for BR. This field can be ignored by default.

    If the field is not configured, the default tableFilter value for TiDB Lightning is as follows:

    tableFilter:
    - "*.*"
    - "!/^(mysql|test|INFORMATION_SCHEMA|PERFORMANCE_SCHEMA|METRICS_SCHEMA|INSPECTION_SCHEMA)$/.*"

    If this field is not configured, BR restores all the schemas in the backup file.

    Note:

    To use the table filter to exclude db.table, you need to first add the *.* rule to include all tables. For example:

    tableFilter:
    - "*.*"
    - "!db.table"
  • .spec.br: BR-related configuration. Refer to BR fields.

  • .spec.s3: S3-related configuration. Refer to S3 storage fields.

  • .spec.gcs: GCS-related configuration. Refer to GCS fields.

  • .spec.local: Persistent volume-related configuration. Refer to Local storage fields.

BackupSchedule CR fields

The backupSchedule configuration consists of two parts. One is the unique configuration of backupSchedule, and the other is backupTemplate. backupTemplate specifies the configuration related to the cluster and remote storage, which is the same as the spec configuration of the Backup CR.

The unique configuration items of backupSchedule are as follows:

  • .spec.maxBackups: A backup retention policy, which determines the maximum number of backup files to be retained. When the number of backup files exceeds this value, the outdated backup file will be deleted. If you set this field to 0, all backup items are retained.
  • .spec.maxReservedTime: A backup retention policy based on time. For example, if you set the value of this field to 24h, only backup files within the recent 24 hours are retained. All backup files older than this value are deleted. For the time format, refer to func ParseDuration. If you have set .spec.maxBackups and .spec.maxReservedTime at the same time, the latter takes effect.
  • .spec.schedule: The time scheduling format of Cron. Refer to Cron for details.
  • .spec.pause: false by default. If this field is set to true, the scheduled scheduling is paused. In this situation, the backup operation will not be performed even if the scheduling time is reached. During this pause, the backup Garbage Collection runs normally. If you change true to false, the scheduled full backup process is restarted.

Delete the Backup CR

You can delete the Backup CR or BackupSchedule CR by running the following commands:

kubectl delete backup ${name} -n ${namespace}
kubectl delete backupschedule ${name} -n ${namespace}

If you use TiDB Operator v1.1.2 or an earlier version, or if you use TiDB Operator v1.1.3 or a later version and set the value of spec.cleanPolicy to Delete, TiDB Operator deletes the backup data when it deletes the CR.

In such cases, if you need to delete the namespace, it is recommended that you first delete all the Backup/BackupSchedule CRs and then delete the namespace.

If you delete the namespace before you delete the Backup/BackupSchedule CR, TiDB Operator will keep creating jobs to clean the backup data. However, because the namespace is in Terminating state, TiDB Operator fails to create such a job, which causes the namespace to be stuck in this state.

To address this issue, delete finalizers by running the following command:

kubectl edit backup ${name} -n ${namespace}

After deleting the metadata.finalizers configuration, you can delete the CR normally.