问题：cosbench read测试failed 报错如下

Cosbench v0.4.2.c4 against Ceph (Hammer) / radosgw / HAproxy‘s HTTP end point. All seems fine except that at the end of the read test, it failed the task and gave following errors

com.amazonaws.AmazonClientException: Unable to verify integrity of data download.  Client calculated content hash didn‘t match hash calculated by Amazon S3.  The data may be corrupt.
        at com.amazonaws.services.s3.internal.DigestValidationInputStream.validateMD5Digest(DigestValidationInputStream.java:79)
        at com.amazonaws.services.s3.internal.DigestValidationInputStream.read(DigestValidationInputStream.java:61)
        at com.amazonaws.internal.SdkFilterInputStream.read(SdkFilterInputStream.java:72)
        at com.amazonaws.services.s3.model.S3ObjectInputStream.read(S3ObjectInputStream.java:155)
        at com.amazonaws.services.s3.model.S3ObjectInputStream.read(S3ObjectInputStream.java:147)
        at com.intel.cosbench.driver.operator.Reader.copyLarge(Reader.java:120)
        at com.intel.cosbench.driver.operator.Reader.doRead(Reader.java:92)
        at com.intel.cosbench.driver.operator.Reader.operate(Reader.java:69)
        at com.intel.cosbench.driver.operator.AbstractOperator.operate(AbstractOperator.java:76)
        at com.intel.cosbench.driver.agent.WorkAgent.performOperation(WorkAgent.java:197)
        at com.intel.cosbench.driver.agent.WorkAgent.doWork(WorkAgent.java:177)
        at com.intel.cosbench.driver.agent.WorkAgent.execute(WorkAgent.java:134)
        at com.intel.cosbench.driver.agent.AbstractAgent.call(AbstractAgent.java:44)
        at com.intel.cosbench.driver.agent.AbstractAgent.call(AbstractAgent.java:1)
        at java.util.concurrent.FutureTask.run(FutureTask.java:262)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
        at java.lang.Thread.run(Thread.java:745)

解决方案：

1. stop all cosbench processes (controller, drivers)
2. edit cosbench-start.sh, locate the java launching line, and add "-Dcom.amazonaws.services.s3.disableGetObjectMD5Validation=true"
3. restart cosbench processes.

cosbench read异常解决办法。 Unable to verify integrity of data download. Client calculated content hash didn't match hash calculated by Amazon S3. The data may be corrupt.