[HBASE-14247] Separate the old WALs into different regionserver directories

• Type: Improvement
• Status: Closed
• Priority: Critical
• Resolution: Fixed
• Fix Version/s: 2.0.0-alpha-4, 2.0.0
• Component/s: wal
• Hadoop Flags: Incompatible change

Release Note

Add a new config hbase.separate.oldlogdir.by.regionserver. The default value is false. If this config is true, the old wal dir will be separated by regionservers. This will change the oldWALs layout. The oldWALs is used by replication. So if a cluster didn't use replication, it can be rolling upgrade (upgrade this config from false to true) directly. If a cluster use replication, the oldWALs will be not found when layout changed. So the cluster need rolling upgrade twice. Firstly, only rolling cluster to use new version code. Secondly rolling the config from false to true. Because the cluster already rolling to new version code, so it can find the oldWALs in the new dir layout.

• Assignee: Guanghao Zhang
• Reporter: Shaohui Liu
• Created: 19/Aug/15 03:30
• Updated: 01/Jul/22 20:58
• Resolved: 17/Oct/17 11:43

Description

Currently all old WALs of regionservers are achieved into the single directory of oldWALs. In big clusters, because of long TTL of WAL or disabled replications, the number of files under oldWALs may reach the max-directory-items limit of HDFS, which will make the hbase cluster crashed.

Caused by: org.apache.hadoop.ipc.RemoteException(org.apache.hadoop.hdfs.protocol.FSLimitException$MaxDirectoryItemsExceededException): The directory item limit of /hbase/lgprc-xiaomi/.oldlogs is exceeded: limit=1048576 items=1048576

A simple solution is to separate the old WALs into different directories according to the server name of the WAL.

Suggestions are welcomed~ Thanks

Issue Links

• is duplicated by: HBASE-17892 Hierarchical paths for WALs
• is related to: HBASE-18309 Support multi threads in CleanerChore
• links to: Review Board (master)