[jira] [Created] (HDFS-14317) Standby does not trigger edit log rolling when in-progress edit log tailing is enabled

["Ekanth Sethuramalingam (JIRA)" <ji...@apache.org>]

Ekanth Sethuramalingam created HDFS-14317:
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             Summary: Standby does not trigger edit log rolling when in-progress edit log tailing is enabled
                 Key: HDFS-14317
                 URL: https://issues.apache.org/jira/browse/HDFS-14317
             Project: Hadoop HDFS
          Issue Type: Bug
    Affects Versions: 3.0.0, 2.9.0
            Reporter: Ekanth Sethuramalingam
            Assignee: Ekanth Sethuramalingam


The standby uses the following method to check if it is time to trigger edit log rolling on active.

{{/**}}
 \{{ * @return true if the configured log roll period has elapsed.}}
 \{{ */}}
 {{private boolean tooLongSinceLastLoad() {}}
 \{{  return logRollPeriodMs >= 0 && }}
 {{   (monotonicNow() - lastLoadTimeMs) > logRollPeriodMs ;}}
 {{}}}

In doTailEdits(), lastLoadTimeMs is updated when standby is able to successfully tail any edits

{{if (editsLoaded > 0) {}}
 {{  lastLoadTimeMs = monotonicNow();}}
 {{}}}

The default configuration for {{dfs.ha.log-roll.period}} is 120 seconds and {{dfs.ha.tail-edits.period}} is 60 seconds. With in-progress edit log tailing enabled, tooLongSinceLastLoad() will almost never return true resulting in edit logs not rolled for a long time until this configuration {{dfs.namenode.edit.log.autoroll.multiplier.threshold}} takes effect.

[In our deployment, this resulted in in-progress edit logs getting deleted. The sequence of events is that standby was able to checkpoint twice while the in-progress edit log was growing on active. When the NNStorageRetentionManager decided to cleanup old checkpoints and edit logs, it cleaned up the in-progress edit log from active and QJM (as the txnid on in-progress edit log was older than the 2 most recent checkpoints) resulting in irrecoverably losing a few minutes worth of metadata].



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