We already allow you to start without a collocated DN.  The
shortcircuit read check only gives an error if shortcircuit reads are
enabled, but misconfigured. You should make sure you aren't setting
dfs.client.read.shortcircuit=true on this cluster.

On Mon, Apr 10, 2017 at 12:24 PM, Marcel Kornacker <[email protected]> wrote:
> We want to reduce the number of startup flags.
>
> Does it make more sense simply not to regard starting without a
> collocated DN as a config error?
>
> On Mon, Apr 10, 2017 at 12:09 PM, Mostafa Mokhtar <[email protected]> 
> wrote:
>> When deploying Impala on hosts without a co-located HDFS Data node Impala
>> won't start, unless abort_on_config_error=false is passed as a safety valve.
>>
>> Concern is that abort_on_config_error checks more than just Short circuit
>> reads.
>>
>> Does it make sense to move Short circuit read check out of
>> abort_on_config_error or put it in a separate flag?
>>
>> fe/src/main/java/org/apache/impala/service/JniFrontend.java
>>   /**
>>    * Returns an error string describing all configuration issues. If no
>> config issues are
>>    * found, returns an empty string.
>>    */
>>   public String checkConfiguration() {
>>     StringBuilder output = new StringBuilder();
>>     output.append(checkLogFilePermission());
>>     output.append(checkFileSystem(CONF));
>>     output.append(checkShortCircuitRead(CONF));
>>     return output.toString();
>>   }
>>
>> be/src/service/impala-server.cc
>>   Status status = exec_env_->frontend()->ValidateSettings();
>>   if (!status.ok()) {
>>     LOG(ERROR) << status.GetDetail();
>>     if (FLAGS_abort_on_config_error) {
>>       CLEAN_EXIT_WITH_ERROR(
>>           "Aborting Impala Server startup due to improper configuration");
>>     }
>>   }
>>
>>   status = exec_env->tmp_file_mgr()->Init(exec_env->metrics());
>>   if (!status.ok()) {
>>     LOG(ERROR) << status.GetDetail();
>>     if (FLAGS_abort_on_config_error) {
>>       CLEAN_EXIT_WITH_ERROR("Aborting Impala Server startup due to
>> improperly "
>>            "configured scratch directories.");
>>     }

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