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Perform Log Backup and Restoration Using BR

You can perform log backup and restoration on a TiDB cluster by using the br log command. This document describes the usage of the br log command.

Prerequisites

Install BR

Before performing log backup, you need to install Backup & Restore (BR). You can install BR via either of the following methods:

Enable log backup

Before you use log backup, ensure that log-backup.enable in the TiKV configuration file is in its default value true. For the method to modify configuration, refer to Modify the configuration.

Perform log backup

You can perform log backup using the br log command. This command has a set of subcommands that help you with the following operations:

  • Start a log backup
  • Query the backup status
  • Pause and resume the backup
  • Stop the backup task and delete the backup data
  • Clean up the backup data
  • View the metadata

This section introduces the subcommands of br log and gives examples of the command usage.

br log subcommands

You can view the br log command help information by running the following command:

./br log --help backup stream log from TiDB/TiKV cluster Usage: br log [command] Available Commands: metadata get the metadata of log dir pause pause a log backup task resume resume a log backup task start start a log backup task status get status for the log backup task stop stop a log backup task truncate truncate the log data until sometime

Each subcommand is described as follows:

  • br log start: start a log backup task.
  • br log status: query the status of the log backup task.
  • br log pause: pause a log backup task.
  • br log resume: resume a paused log backup task.
  • br log stop: stop a log backup task and delete the task metadata.
  • br log truncate: clean up the log backup data from the backup storage.
  • br log metadata: query the metadata of the log backup data.

Start a backup task

You can run the br log start command to start a log backup task. This task runs in the background of your TiDB cluster and automatically backs up the change log of KV storage to the backup storage.

Run br log start --help to see the help information:

./br log start --help start a log backup task Usage: br log start [flags] Flags: -h, --help help for start --start-ts string usually equals last full backupTS, used for backup log. Default value is current ts. support TSO or datetime, e.g. '400036290571534337' or '2018-05-11 01:42:23+0800'. --task-name string The task name for the backup log task. Global Flags: --ca string CA certificate path for TLS connection --cert string Certificate path for TLS connection --key string Private key path for TLS connection -u, --pd strings PD address (default [127.0.0.1:2379]) -s, --storage string specify the url where backup storage, eg, "s3://bucket/path/prefix"

The example output only shows the common parameters. These parameters are described as follows:

  • --task-name: specify the task name for the log backup. This name is also used to query, pause, and resume the backup task.
  • --start-ts: specify the start timestamp for the log backup. If this is not specified, the backup program uses the current time as start-ts.
  • --pd: specify the PD address for the backup cluster. BR needs to access PD to start the log backup task.
  • --ca, --cert, --key: specify the mTLS encryption method to communicate with TiKV and PD.
  • --storage: specify the backup storage address. Currently, BR supports shared file systems, Amazon S3, GCS, or Azure Blob Storage as the storage for log backup. For details, see Amazon S3 storage, GCS storage, and Azure blob storage.

Usage example:

./br log start --task-name=pitr --pd=172.16.102.95:2379 --storage='s3://tidb-pitr-bucket/backup-data/log-backup'

Query the backup status

You can run the br log status command to query the backup status.

Run br log status --help to see the help information:

./br log status --help get status for the log backup task Usage: br log status [flags] Flags: -h, --help help for status --json Print JSON as the output. --task-name string The task name for backup stream log. If default, get status of all of tasks (default "*") Global Flags: --ca string CA certificate path for TLS connection --cert string Certificate path for TLS connection --key string Private key path for TLS connection -u, --pd strings PD address (default [127.0.0.1:2379])

In the example output, task-name is used to specify the name of the backup task. The default value is *, which means querying the status of all tasks.

Usage example:

./br log status --task-name=pitr --pd=172.16.102.95:2379 ● Total 1 Tasks. > #1 < name: pitr status: ● NORMAL start: 2022-07-14 20:08:03.268 +0800 end: 2090-11-18 22:07:45.624 +0800 storage: s3://tmp/store-by-storeid/log1 speed(est.): 0.82 ops/s checkpoint[global]: 2022-07-25 22:52:15.518 +0800; gap=2m52s

The output fields are described as follows:

  • status: the status of the backup task. The status can be NORMAL, ERROR, or PAUSE.
  • start: the start time of the backup task. It is the start-ts value specified when the backup task is started.
  • storage: the backup storage address.
  • speed: the total QPS of the backup task. QPS means the number of logs backed per second.
  • checkpoint[global]: all data before this checkpoint is backed up to the backup storage. This is the latest timestamp available for restoring the backup data.
  • error[store]: the error the log backup program encounters on the storage node.

Pause and resume the backup task

You can run the br log pause command to pause a running backup task.

Run br log pause --help to see the help information:

./br log pause --help pause a log backup task Usage: br log pause [flags] Flags: --gc-ttl int the TTL (in seconds) that PD holds for BR's GC safepoint (default 86400) -h, --help help for status --task-name string The task name for backup stream log. Global Flags: --ca string CA certificate path for TLS connection --cert string Certificate path for TLS connection --key string Private key path for TLS connection -u, --pd strings PD address (default [127.0.0.1:2379])

Usage example:

./br log pause --task-name=pitr --pd=172.16.102.95:2379

You can run the br log resume command to resume the paused backup task.

Run br log resume --help to see the help information:

./br log resume --help resume a log backup task Usage: br log resume [flags] Flags: -h, --help help for status --task-name string The task name for backup stream log. Global Flags: --ca string CA certificate path for TLS connection --cert string Certificate path for TLS connection --key string Private key path for TLS connection -u, --pd strings PD address (default [127.0.0.1:2379])

After the backup task is paused for more than 24 hours, running br log resume reports an error, and BR prompts that backup data is lost. To handle this error, refer to Troubleshoot PITR Log Backup.

Usage example:

./br log resume --task-name=pitr --pd=172.16.102.95:2379

Stop the backup task (permanently)

You can run the br log stop command to stop a log backup task permanently. This command cleans up the task metadata in the backup cluster.

Run br log stop --help to see the help information:

./br log stop --help stop a log backup task Usage: br log stop [flags] Flags: -h, --help help for status --task-name string The task name for the backup log task. Global Flags: --ca string CA certificate path for TLS connection --cert string Certificate path for TLS connection --key string Private key path for TLS connection -u, --pd strings PD address (default [127.0.0.1:2379])

Usage example:

./br log stop --task-name=pitr --pd=172.16.102.95:2379

Clean up the backup data

You can run the br log truncate command to clean up the outdated or no longer needed log backup data.

Run br log truncate --help to see the help information:

./br log truncate --help truncate the incremental log until sometime. Usage: br log truncate [flags] Flags: --dry-run Run the command but don't really delete the files. -h, --help help for truncate --until string Remove all backup data until this TS.(support TSO or datetime, e.g. '400036290571534337' or '2018-05-11 01:42:23+0800'.) -y, --yes Skip all prompts and always execute the command. Global Flags: -s, --storage string specify the url where backup storage, eg, "s3://bucket/path/prefix"

This command only accesses the backup storage, but does not access the TiDB cluster.

Some parameters are described as follows:

  • --dry-run: run the command but do not really delete the files.
  • --until: delete all log backup data before the specified timestamp.
  • --storage: the backup storage address. Currently, BR supports shared file systems, Amazon S3, GCS, or Azure Blob Storage as the storage for log backup. For details, see Amazon S3 storage, GCS storage, and Azure blob storage.

Usage example:

./br log truncate --until='2022-07-26 21:20:00+0800' –-storage='s3://tidb-pitr-bucket/backup-data/log-backup'

Expected output:

Reading Metadata... DONE; take = 277.911599ms We are going to remove 9 files, until 2022-07-26 21:20:00.0000. Sure? (y/N) y Clearing data files... DONE; take = 43.504161ms, kv-count = 53, kv-size = 4573(4.573kB) Removing metadata... DONE; take = 24.038962ms

View the backup metadata

You can run the br log metadata command to view the metadata of the log backup in the backup storage, such as the earliest and latest timestamp that can be restored.

Run br log metadata --help to see the help information:

./br log metadata --help get the metadata of log backup storage Usage: br log metadata [flags] Flags: -h, --help help for metadata Global Flags: -s, --storage string specify the url where backup storage, eg, "s3://bucket/path/prefix"

This command only accesses the backup storage, but does not access the TiDB cluster.

The --storage parameter is used to specify the backup storage address. Currently, BR supports shared file systems, Amazon S3, GCS, or Azure Blob Storage as the storage for log backup. For details, see Amazon S3 storage, GCS storage, and Azure blob storage.

Usage example:

./br log metadata –-storage='s3://tidb-pitr-bucket/backup-data/log-backup'

Expected output:

[2022/07/25 23:02:57.236 +08:00] [INFO] [collector.go:69] ["log metadata"] [log-min-ts=434582449885806593] [log-min-date="2022-07-14 20:08:03.268 +0800"] [log-max-ts=434834300106964993] [log-max-date="2022-07-25 23:00:15.618 +0800"]

Restore the log backup data

You can run the br restore point command to perform a PITR on a new cluster or just restore the log backup data.

Run br restore point --help to see the help information:

./br restore point --help restore data from log until specify commit timestamp Usage: br restore point [flags] Flags: --full-backup-storage string specify the backup full storage. fill it if want restore full backup before restore log. -h, --help help for point --restored-ts string the point of restore, used for log restore. support TSO or datetime, e.g. '400036290571534337' or '2018-05-11 01:42:23+0800' --start-ts string the start timestamp which log restore from. support TSO or datetime, e.g. '400036290571534337' or '2018-05-11 01:42:23+0800' Global Flags: --ca string CA certificate path for TLS connection --cert string Certificate path for TLS connection --key string Private key path for TLS connection -u, --pd strings PD address (default [127.0.0.1:2379]) -s, --storage string specify the url where backup storage, eg, "s3://bucket/path/prefix"

The example output only shows the common parameters. These parameters are described as follows:

  • --full-backup-storage: the storage address for the snapshot (full) backup. If you need to use PITR, you must specify this parameter and choose the latest snapshot backup before the restoration timestamp. If you only need to restore log backup data, you can omit this parameter. Currently, BR supports shared file systems, Amazon S3, GCS, or Azure Blob Storage as the storage for log backup. For details, see Amazon S3 storage, GCS storage, and Azure blob storage.
  • --restored-ts: the timestamp that you want to restore data to. If this parameter is not specified, BR restores data to the latest timestamp available in the log backup, that is, the checkpoint of the backup data.
  • --start-ts: the start timestamp that you want to restore log backup data from. If you only need to restore log backup data and do not need snapshot backup data, you must specify this parameter.
  • --pd: the PD address of the restoration cluster.
  • --ca, --cert, --key: specify the mTLS encryption method to communicate with TiKV and PD.
  • --storage: the storage address for the log backup. Currently, BR supports shared file systems, Amazon S3, GCS, or Azure Blob Storage as the storage for log backup. For details, see Amazon S3 storage, GCS storage, and Azure blob storage.

Usage example:

./br restore point --pd=172.16.102.95:2379 --storage='s3://tidb-pitr-bucket/backup-data/log-backup' --full-backup-storage='s3://tidb-pitr-bucket/backup-data/snapshot-20220512000000' Full Restore <--------------------------------------------------------------------------------------------------------------------------------------------------------> 100.00% [2022/07/19 18:15:39.132 +08:00] [INFO] [collector.go:69] ["Full Restore success summary"] [total-ranges=12] [ranges-succeed=12] [ranges-failed=0] [split-region=546.663µs] [restore-ranges=3] [total-take=3.112928252s] [restore-data-size(after-compressed)=5.056kB] [Size=5056] [BackupTS=434693927394607136] [total-kv=4] [total-kv-size=290B] [average-speed=93.16B/s] Restore Meta Files <--------------------------------------------------------------------------------------------------------------------------------------------------> 100.00% Restore KV Files <----------------------------------------------------------------------------------------------------------------------------------------------------> 100.00% [2022/07/19 18:15:39.325 +08:00] [INFO] [collector.go:69] ["restore log success summary"] [total-take=192.955533ms] [restore-from=434693681289625602] [restore-to=434693753549881345] [total-kv-count=33] [total-size=21551]
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