:original_name: mrs_01_1643.html

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Why Does the HBase BulkLoad Task (One Table Has 26 TB Data) Consisting of 210,000 Map Tasks and 10,000 Reduce Tasks Fail?
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Question
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The HBase bulkLoad task (a single table contains 26 TB data) has 210,000 maps and 10,000 reduce tasks, and the task fails.

Answer
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**ZooKeeper I/O bottleneck observation methods:**

#. On the monitoring page of Manager, check whether the number of ZooKeeper requests on a single node exceeds the upper limit.
#. View ZooKeeper and HBase logs to check whether a large number of I/O Exception Timeout or SocketTimeout Exception exceptions occur.

**Optimization suggestions:**

#. Change the number of ZooKeeper instances to 5 or more. You are advised to set **peerType** to **observer** to increase the number of observers.
#. Control the number of concurrent maps of a single task or reduce the memory for running tasks on each node to lighten the node load.
#. Upgrade ZooKeeper data disks, such as SSDs.
