[HDFS-11090] Leave safemode immediately if all blocks have reported in

• Type: Improvement
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 2.7.3
• Component/s: namenode
• Assignee: Yiqun Lin
• Reporter: Andrew Wang
• Created: 02/Nov/16 01:09
• Updated: 18/Nov/19 22:41

Description

Startup safemode is triggered by two thresholds: % blocks reported in, and min # datanodes. It's extended by an interval (default 30s) until these two thresholds are met.

Safemode extension is helpful when the cluster has data, and the default % blocks threshold (0.99) is used. It gives DNs a little extra time to report in and thus avoid unnecessary replication work.

However, we can leave startup safemode early if 100% of blocks have reported in.

Note that operators sometimes change the % blocks threshold to > 1 to never automatically leave safemode. We should maintain this behavior.

Issue Links

• relates to: HDFS-14952 Skip safemode if blockTotal is 0 in new NN