后经排查发现tiflash的配置文件有点问题出现如下报错：
“I1206 10:09:03.063579 1 event.go:282] Event(v1.ObjectReference{Kind:“TidbCluster”, Namespace:“tidb”, Name:“yz”, UID:“50b1bdbc-629c-424e-9247-e36426ebd23c”, APIVersion:“pingcap.com/v1alpha1”, ResourceVersion:“52683256”, FieldPath:“”}): type: ‘Warning’ reason: ‘FailedUpdateTiFlashSTS’ contains volumeMounts that do not have matched volume: map[data1:{data1 false /data1 }]
E1206 10:09:16.330147 1 tidb_cluster_controller.go:126] TidbCluster: tidb/yz, sync failed contains volumeMounts that do not have matched volume: map[data1:{data1 false /data1 }], requeuing
I1206 10:09:16.330561 1 event.go:282] Event(v1.ObjectReference{Kind:“TidbCluster”, Namespace:“tidb”, Name:“yz”, UID:“50b1bdbc-629c-424e-9247-e36426ebd23c”, APIVersion:“pingcap.com/v1alpha1”, ResourceVersion:“52683256”, FieldPath:“”}): type: ‘Warning’ reason: ‘FailedUpdateTiFlashSTS’ contains volumeMounts that do not have matched volume: map[data1:{data1 false /data1 }]”
后来把配置文件在线去除掉，保留如下：
报错没有了，pod能正常扩容了。
扩容如下：
[root@k8s-master tidb]# kubectl patch -n tidb tc yz --type merge --patch '{"spec":{"tiflash":{"replicas":3}}}'
tidbcluster.pingcap.com/yz patched
[root@k8s-master tidb]# kubectl get pod -ntidb
tidbngmonitoring-lqb-ng-monitoring-0 1/1 Running 0 138m
yz-discovery-6c89b45d5d-nkps7 1/1 Running 1 26h
yz-pd-0 1/1 Running 2 26h
yz-tidb-0 2/2 Running 2 26h
yz-tidb-1 2/2 Running 0 4m15s
yz-tiflash-0 4/4 Running 0 29m
yz-tiflash-1 4/4 Running 0 4m15s
yz-tiflash-2 4/4 Running 0 7s
yz-tikv-0 1/1 Running 1 26h
yz-tikv-1 1/1 Running 1 6h43m
yz-tikv-2 1/1 Running 0 77m
问题解决