Tencent COS

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This guide describes the instructions to configure Tencent COS as Alluxio’s under storage system.

Alluxio support two different implementations of under storage system for Tencent COS:

  • COS
    Tencent Cloud Object Storage (COS) is a distributed storage service offered by Tencent Cloud for unstructured data and accessible via HTTP/HTTPS protocols. It can store massive amounts of data and features imperceptible bandwidth and capacity expansion, making it a perfect data pool for big data computation and analytics.
    For more information about Tencent COS, please read its documentation.
  • COSN, also known as Hadoop-COS
    COSN is a client that makes the upper computing systems based on HDFS be able to use Tencent COS as its underlying storage system.
    For more information about COSN, please read its documentation.


If you haven’t already, please see Prerequisites before you get started.

In preparation for using COS or COSN with Alluxio:

Basic Setup

After these changes, Alluxio should be configured to work with COS or COSN as its under storage system.

Running Alluxio Locally with COS/COSN

Once you have configured Alluxio to Tencent COS or COSN, try running Alluxio locally to see that everything works.

Advanced Setup

[Experimental] COS multipart upload

The default upload method uploads one file completely from start to end in one go. We use multipart-upload method to upload one file by multiple parts, every part will be uploaded in one thread. It won’t generate any temporary files while uploading.

To enable COS multipart upload, you need to modify conf/alluxio-site.properties to include:


There are other parameters you can specify in conf/alluxio-site.properties to make the process faster and better.

# Timeout for uploading part when using multipart upload.
# Thread pool size for COS multipart upload.
# Multipart upload partition size for COS. The default partition size is 64MB. 

Contributed by the Alluxio Community

Tencent COS and COSN UFS integration is contributed and maintained by the Alluxio community. The source code for COS is located here and for COSN is located here. Feel free submit pull requests to improve the integration and update the documentation here if any information is missing or out of date.