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Stephen O'Donnell commented on HDFS-16423: ------------------------------------------ I have a question on this Jira. As I understand it, the namenode marks all storages stale after a failover. The only way the storage is marked as "not stale" is when a FBR is sent from the datanode. This FBR interval is 6 hours by default, but some set it higher. I don't think there is any mechanism to trigger the FBR early due to the failover. If we tell the balancer to not pick blocks from stale storages, then after a failover the balancer will effectively not work at all for up to the FBR interval, as there will be no storages for it to pick blocks from. Is that correct? I wonder if we should log a message in the NN indicating "all storages as stale" to help people understand that is why the balancer is not working? Probably, the balancer will try 5 times to get some blocks to move and then give up with a "failed to move any blocks in 5 iterations" message. > balancer should not get blocks on stale storages > ------------------------------------------------ > > Key: HDFS-16423 > URL: https://issues.apache.org/jira/browse/HDFS-16423 > Project: Hadoop HDFS > Issue Type: Improvement > Components: balancer & mover > Reporter: qinyuren > Assignee: qinyuren > Priority: Major > Labels: pull-request-available > Fix For: 3.4.0, 3.3.3 > > Attachments: image-2022-01-13-17-18-32-409.png > > Time Spent: 4h 20m > Remaining Estimate: 0h > > We have met a problems as described in HDFS-16420 > We found that balancer copied a block multi times without deleting the source > block if this block was placed in a stale storage. And resulting a block with > many copies, but these redundant copies are not deleted until the storage > become not stale. > > !image-2022-01-13-17-18-32-409.png|width=657,height=275! -- This message was sent by Atlassian Jira (v8.20.1#820001) --------------------------------------------------------------------- To unsubscribe, e-mail: hdfs-issues-unsubscr...@hadoop.apache.org For additional commands, e-mail: hdfs-issues-h...@hadoop.apache.org