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】
【概述】 将mysql迁移到tidb，已使用dumpling将mysql数据库导出，但使用lightning工具导入的时候，就会出现pd不可用情况。
【备份和数据迁移策略逻辑】
【背景】 将mysql迁移到tidb，已使用dumpling将mysql数据库导出，但使用lightning工具导入的时候，就会出现pd不可用情况。是否需要调整哪些配置
【现象】 使用lightning迁移数据失败，提示 pd unavailable
【问题】 使用lightning迁移数据失败，提示 pd unavailable
【业务影响】 使用lightning迁移数据失败，提示 pd unavailable
【TiDB 版本】 5.3
Lightning日志
[2021/12/18 20:14:54.893 +08:00] [WARN] [localhelper.go:153] [“fetch table region size statistics failed”] [table=punish_history] [error=“fetch region approx
imate sizes failed: Error 1105: pd unavailable”] [errorVerbose="Error 1105: pd unavailable\ngithub.com/pingcap/errors.AddStack\
\t/nfs/cache/mod/github.com/p
ingcap/errors@v0.11.5-0.20210425183316-da1aaba5fb63/errors.go:174\ngithub.com/pingcap/errors.Trace\
\t/nfs/cache/mod/github.com/pingcap/errors@v0.11.5-0.2021
0425183316-da1aaba5fb63/juju_adaptor.go:15\ngithub.com/pingcap/tidb/br/pkg/lightning/backend/local.fetchTableRegionSizeStats.func1\
\t/home/jenkins/agent/wor
kspace/optimization-build-tidb-linux-amd/go/src/github.com/pingcap/br/br/pkg/lightning/backend/local/localhelper.go:342\ngithub.com/pingcap/tidb/br/pkg/light
ning/common.SQLWithRetry.Transact.func1\
\t/home/jenkins/agent/workspace/optimization-build-tidb-linux-amd/go/src/github.com/pingcap/br/br/pkg/lightning/comm
on/util.go:156\ngithub.com/pingcap/tidb/br/pkg/lightning/common.Retry\
\t/home/jenkins/agent/workspace/optimization-build-tidb-linux-amd/go/src/github.com/pi
ngcap/br/br/pkg/lightning/common/util.go:118\ngithub.com/pingcap/tidb/br/pkg/lightning/common.SQLWithRetry.perform\
\t/home/jenkins/agent/workspace/optimizat
ion-build-tidb-linux-amd/go/src/github.com/pingcap/br/br/pkg/lightning/common/util.go:103\ngithub.com/pingcap/tidb/br/pkg/lightning/common.SQLWithRetry.Trans
act\
\t/home/jenkins/agent/workspace/optimization-build-tidb-linux-amd/go/src/github.com/pingcap/br/br/pkg/lightning/common/util.go:150\ngithub.com/pingcap/t
idb/br/pkg/lightning/backend/local.fetchTableRegionSizeStats\
\t/home/jenkins/agent/workspace/optimization-build-tidb-linux-amd/go/src/github.com/pingcap/br/
br/pkg/lightning/backend/local/localhelper.go:339\ngithub.com/pingcap/tidb/br/pkg/lightning/backend/local.(*local).SplitAndScatterRegionByRanges\
\t/home/jen
kins/agent/workspace/optimization-build-tidb-linux-amd/go/src/github.com/pingcap/br/br/pkg/lightning/backend/local/localhelper.go:151\ngithub.com/pingcap/tid
b/br/pkg/lightning/backend/local.(*local).ImportEngine\
\t/home/jenkins/agent/workspace/optimization-build-tidb-linux-amd/go/src/github.com/pingcap/br/br/pkg
/lightning/backend/local/local.go:2063\ngithub.com/pingcap/tidb/br/pkg/lightning/backend.(*ClosedEngine).Import\
\t/home/jenkins/agent/workspace/optimization
-build-tidb-linux-amd/go/src/github.com/pingcap/br/br/pkg/lightning/backend/backend.go:453\ngithub.com/pingcap/tidb/br/pkg/lightning/restore.(*TableRestore).
PD日志
[2021/12/18 20:14:36.611 +08:00] [INFO] [server.go:832] [“schedule config is updated”] [new="{“max-snapshot-count”:40,“max-pending-peer-count”:2147483647
,“max-merge-region-size”:0,“max-merge-region-keys”:0,“split-merge-interval”:“1h0m0s”,“enable-one-way-merge”:“false”,“enable-cross-table-merge”:
“true”,“patrol-region-interval”:“10ms”,“max-store-down-time”:“30m0s”,“leader-schedule-limit”:4,“leader-schedule-policy”:“count”,“region-sche
dule-limit”:40,“replica-schedule-limit”:64,“merge-schedule-limit”:8,“hot-region-schedule-limit”:4,“hot-region-cache-hits-threshold”:3,“store-limit
“:{“1”:{“add-peer”:15,“remove-peer”:15}},“tolerant-size-ratio”:0,“low-space-ratio”:0.8,“high-space-ratio”:0.7,“region-score-formula-version”:”
v2”,“scheduler-max-waiting-operator”:5,“enable-remove-down-replica”:“true”,“enable-replace-offline-replica”:“true”,“enable-make-up-replica”:“tr
ue”,“enable-remove-extra-replica”:“true”,“enable-location-replacement”:“false”,“enable-debug-metrics”:“false”,“enable-joint-consensus”:“true
“,“schedulers-v2”:[{“type”:“balance-region”,“args”:null,“disable”:false,“args-payload”:””},{“type”:“balance-leader”,“args”:null,“disable
“:false,“args-payload”:””},{“type”:“hot-region”,“args”:null,“disable”:false,“args-payload”:""}],“schedulers-payload”:null,“store-limit-mo
de”:“manual”,“hot-regions-write-interval”:“10m0s”,“hot-regions-reserved-days”:0}"] [old="{“max-snapshot-count”:64,“max-pending-peer-count”:64,"
max-merge-region-size":20,“max-merge-region-keys”:200000,“split-merge-interval”:“1h0m0s”,“enable-one-way-merge”:“false”,“enable-cross-table-merge
“:“true”,“patrol-region-interval”:“10ms”,“max-store-down-time”:“30m0s”,“leader-schedule-limit”:4,“leader-schedule-policy”:“count”,“region-s
chedule-limit”:2048,“replica-schedule-limit”:64,“merge-schedule-limit”:8,“hot-region-schedule-limit”:4,“hot-region-cache-hits-threshold”:3,“store-l
imit”:{“1”:{“add-peer”:15,“remove-peer”:15}},“tolerant-size-ratio”:0,“low-space-ratio”:0.8,“high-space-ratio”:0.7,“region-score-formula-version
“:“v2”,“scheduler-max-waiting-operator”:5,“enable-remove-down-replica”:“true”,“enable-replace-offline-replica”:“true”,“enable-make-up-replica”
:“true”,“enable-remove-extra-replica”:“true”,“enable-location-replacement”:“true”,“enable-debug-metrics”:“false”,“enable-joint-consensus”:“t
rue”,“schedulers-v2”:[{“type”:“balance-region”,“args”:null,“disable”:false,“args-payload”:””},{“type”:“balance-leader”,“args”:null,“dis
able”:false,“args-payload”:””},{“type”:“hot-region”,“args”:null,“disable”:false,“args-payload”:""}],“schedulers-payload”:null,“store-limi
t-mode”:“manual”,“hot-regions-write-interval”:“10m0s”,“hot-regions-reserved-days”:0}"]
[2021/12/18 20:14:53.958 +08:00] [INFO] [cluster_worker.go:128] [“alloc ids for region split”] [region-id=4] [peer-ids="[5]"]
[2021/12/18 20:14:53.958 +08:00] [INFO] [cluster_worker.go:128] [“alloc ids for region split”] [region-id=6] [peer-ids="[7]"]
[2021/12/18 20:14:53.958 +08:00] [INFO] [cluster_worker.go:128] [“alloc ids for region split”] [region-id=8] [peer-ids="[9]"]
[2021/12/18 20:14:53.979 +08:00] [INFO] [cluster_worker.go:220] [“region batch split, generate new regions”] [region-id=2] [origin=“id:4 end_key:“7480000000
000000FF3F5F728000000000FF0000010000000000FA” region_epoch:<conf_ver:1 version:4 > peers:<id:5 store_id:1 > id:6 start_key:“7480000000000000FF3F5F728000000
000FF0000010000000000FA” end_key:“7480000000000000FF3F5F728000000000FF01564C0000000000FA” region_epoch:<conf_ver:1 version:4 > peers:<id:7 store_id:1 > id
:8 start_key:“7480000000000000FF3F5F728000000000FF01564C0000000000FA” end_key:“7480000000000000FF3F5F728000000000FF02A8910000000000FA” region_epoch: peers:<id:9 store_id:1 >”] [total=3]