为提高效率，请提供以下信息，问题描述清晰能够更快得到解决：
【 TiDB 使用环境】
docker环境 k8s部署 tikv pd tidb分别部署多台docker上，数据备份到共享存储上
【概述】 场景 + 问题概述
[2021/10/29 12:53:14.210 +00:00] [ERROR] [backup.go:41] [“failed to backup”] [error=“rpc error: code = Canceled desc = context canceled”] [errorVerbose=“rpc error: code = Canceled desc = context canceled\ngithub.com/tikv/pd/client.(*client).GetAllStores\
\tgithub.com/tikv/pd@v1.1.0-beta.0.20210323121136-78679e5e209d/client/client.go:1196\
github.com/pingcap/br/pkg/conn.GetAllTiKVStores\
\tgithub.com/pingcap/br/pkg/conn/conn.go:139\
github.com/pingcap/br/pkg/backup.(*Client).BackupRange\
\tgithub.com/pingcap/br/pkg/backup/client.go:459\
github.com/pingcap/br/pkg/backup.(*Client).BackupRanges.func1\
\tgithub.com/pingcap/br/pkg/backup/client.go:424\
github.com/pingcap/br/pkg/utils.(*WorkerPool).ApplyOnErrorGroup.func1\
\tgithub.com/pingcap/br/pkg/utils/worker.go:63\
golang.org/x/sync/errgroup.(*Group).Go.func1\
\tgolang.org/x/sync@v0.0.0-20210220032951-036812b2e83c/errgroup/errgroup.go:57\
runtime.goexit\
\truntime/asm_amd64.s:1371”] [stack=“main.runBackupCommand\
\tcommand-line-arguments/backup.go:41\
main.newFullBackupCommand.func1\
\tcommand-line-arguments/backup.go:109\ngithub.com/spf13/cobra.(*Command).execute\
\tgithub.com/spf13/cobra@v1.0.0/command.go:842\
github.com/spf13/cobra.(*Command).ExecuteC\
\tgithub.com/spf13/cobra@v1.0.0/command.go:950\
github.com/spf13/cobra.(*Command).Execute\
\tgithub.com/spf13/cobra@v1.0.0/command.go:887\
main.main\
\tcommand-line-arguments/main.go:56\
runtime.main\
\truntime/proc.go:225”]
[2021/10/29 12:53:14.210 +00:00] [ERROR] [main.go:58] [“br failed”] [error=“rpc error: code = Canceled desc = context canceled”] [errorVerbose=“rpc error: code = Canceled desc = context canceled\ngithub.com/tikv/pd/client.(*client).GetAllStores\
\tgithub.com/tikv/pd@v1.1.0-beta.0.20210323121136-78679e5e209d/client/client.go:1196\
github.com/pingcap/br/pkg/conn.GetAllTiKVStores\
\tgithub.com/pingcap/br/pkg/conn/conn.go:139\
github.com/pingcap/br/pkg/backup.(*Client).BackupRange\
\tgithub.com/pingcap/br/pkg/backup/client.go:459\
github.com/pingcap/br/pkg/backup.(*Client).BackupRanges.func1\
\tgithub.com/pingcap/br/pkg/backup/client.go:424\
github.com/pingcap/br/pkg/utils.(*WorkerPool).ApplyOnErrorGroup.func1\
\tgithub.com/pingcap/br/pkg/utils/worker.go:63\
golang.org/x/sync/errgroup.(*Group).Go.func1\
\tgolang.org/x/sync@v0.0.0-20210220032951-036812b2e83c/errgroup/errgroup.go:57\
runtime.goexit\
\truntime/asm_amd64.s:1371”] [stack=“main.main\
\tcommand-line-arguments/main.go:58\
runtime.main\
\truntime/proc.go:225”]
【备份和数据迁移策略逻辑】
执行备份语句 nohup /tidb/bin/br backup full --pd “11.45.241.131:2379” --storage local:///mnt/cfs/cbsql2/extern/tikv/tidb-bigdata/whole-tidb-bigdata-time-2021-10-29 --log-file /export/backup-nfs.log >/export/tikv_dobackup_record.log 2>&1 &
【背景】 做过哪些操作
【现象】 业务和数据库现象
【问题】 当前遇到的问题
[“failed to backup”] [error=“rpc error: code = Canceled desc = context canceled”]
【业务影响】
【TiDB 版本】
TiKV
Release Version: 5.1.1
Edition: Community
Git Commit Hash: 4705d7c6e9c42d129d3309e05911ec6b08a25a38
Git Commit Branch: heads/refs/tags/v5.1.1
UTC Build Time: 2021-07-28 10:59:26
Rust Version: rustc 1.53.0-nightly (16bf626a3 2021-04-14)
Enable Features: jemalloc mem-profiling portable sse protobuf-codec test-engines-rocksdb cloud-aws cloud-gcp
Profile: dist_release
【附件】
- 相关日志、配置文件、Grafana 监控（https://metricstool.pingcap.com/)
- TiUP Cluster Display 信息
- TiUP CLuster Edit config 信息
- TiDB-Overview 监控
- 对应模块的 Grafana 监控（如有 BR、TiDB-binlog、TiCDC 等）
- 对应模块日志（包含问题前后 1 小时日志）
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