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    E-MapReduce:What do I do if I cannot use an EMR cluster to access OSS across regions?

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    E-MapReduce:What do I do if I cannot use an EMR cluster to access OSS across regions?

    Last Updated:Mar 07, 2025

    This topic describes the cause of the issue that E-MapReduce (EMR) clusters cannot be used to access Object Storage Service (OSS) across regions and how to resolve the issue.

    Issue: Fail to wait EPOLLOUT appears during access to OSS

    • Error message:

      [emr-user@core-1-1~]$hadoopfs-lsoss://jindo-oss-runjob-cn-hangzhou.oss-cn-hangzhou.aliyuncs.com/
2022-11-2817:12:19,926WARNjnative.NativeLogger:socket.cpp:1223]FailtowaitEPOLLOUToffd=212
2022-11-2817:12:29,439WARNjnative.NativeLogger:socket.cpp:1223]FailtowaitEPOLLOUToffd=212
2022-11-2817:12:39,452WARNjnative.NativeLogger:socket.cpp:1223]FailtowaitEPOLLOUToffd=212
2022-11-2817:12:50,468WARNjnative.NativeLogger:socket.cpp:1223]FailtowaitEPOLLOUToffd=212
2022-11-2817:12:53,968WARNjnative.NativeLogger:socket.cpp:1223]FailtowaitEPOLLOUToffd=207

    • Cause:

      In the new EMR console, you cannot use a core node of an EMR cluster to access OSS across regions. In the old EMR console, you cannot use a worker node of an EMR cluster to access OSS across regions.

    • Solutions:

      • We recommend that you deploy the OSS bucket that you want to access in the region in which the EMR cluster resides.

      • When you create an EMR cluster, turn on Assign Public Network IP for all nodes in the cluster. If you do not turn on this switch when you create the cluster, you can go to the Elastic Compute Service (ECS) console and apply for an elastic IP address (EIP) for each node in the cluster. This way, you can use the cluster to access the public endpoint of OSS.

        For information about how to turn on Assign Public Network IP, see Create a cluster. For information about how to apply for an EIP in the ECS console, see What is an Elastic IP Address?

      • If you need to perform cross-region replication to meet business requirements, refer to Overview of cross-region replication.

      • If you need to access OSS across regions to meet business requirements, we recommend that you configure an Internet NAT gateway for the virtual private cloud (VPC) or vSwitch of the EMR cluster. For more information, see Use the SNAT feature of an Internet NAT gateway to access the Internet.