Overview of HDFS File System Directories

Hadoop Distributed File System (HDFS) implements reliable and distributed read/write of massive amounts of data. HDFS is applicable to the scenario where data read/write features "write once and read multiple times". However, the write operation is performed in sequence, that is, it is a write operation performed during file creation or an adding operation performed behind the existing file. HDFS ensures that only one caller can perform write operation on a file but multiple callers can perform read operation on the file at the same time.

This section describes the directory structure in HDFS, as shown in the following table.

**Table 1** HDFS directory structure (applicable to versions earlier than MRS 3.x)
Path	Type	Function	Whether the Directory Can Be Deleted	Deletion Consequence
/tmp/spark/sparkhive-scratch	Fixed directory	Stores temporary files of metastore sessions in Spark JDBCServer.	No	Failed to run the task.
/tmp/sparkhive-scratch	Fixed directory	Stores temporary files of metastore session that are executed using Spark CLI.	No	Failed to run the task.
/tmp/carbon/	Fixed directory	Stores the abnormal data in this directory if abnormal CarbonData data exists during data import.	Yes	Error data is lost.
/tmp/Loader-${Job name}_${MR job ID}	Temporary directory	Stores the region information about Loader HBase bulkload jobs. The data is automatically deleted after the job running is completed.	No	Failed to run the Loader HBase Bulkload job.
/tmp/logs	Fixed directory	Stores the collected MR task logs.	Yes	MR task logs are lost.
/tmp/archived	Fixed directory	Archives the MR task logs on HDFS.	Yes	MR task logs are lost.
/tmp/hadoop-yarn/staging	Fixed directory	Stores the run logs, summary information, and configuration attributes of ApplicationMaster running jobs.	No	Services are running improperly.
/tmp/hadoop-yarn/staging/history/done_intermediate	Fixed directory	Stores temporary files in the /tmp/hadoop-yarn/staging directory after all tasks are executed.	No	MR task logs are lost.
/tmp/hadoop-yarn/staging/history/done	Fixed directory	The periodic scanning thread periodically moves the done_intermediate log file to the done directory.	No	MR task logs are lost.
/tmp/mr-history	Fixed directory	Stores the historical record files that are pre-loaded.	No	Historical MR task log data is lost.
/tmp/hive	Fixed directory	Stores Hive temporary files.	No	Failed to run the Hive task.
/tmp/hive-scratch	Fixed directory	Stores temporary data (such as session information) generated during Hive running.	No	Failed to run the current task.
/user/{user}/.sparkStaging	Fixed directory	Stores temporary files of the SparkJDBCServer application.	No	Failed to start the executor.
/user/spark/jars	Fixed directory	Stores running dependency packages of the Spark executor.	No	Failed to start the executor.
/user/loader	Fixed directory	Stores dirty data of Loader jobs and data of HBase jobs.	No	Failed to execute the HBase job. Or dirty data is lost.
/user/loader/etl_dirty_data_dir
/user/loader/etl_hbase_putlist_tmp
/user/loader/etl_hbase_tmp
/user/mapred	Fixed directory	Stores Hadoop-related files.	No	Failed to start Yarn.
/user/hive	Fixed directory	Stores Hive-related data by default, including the depended Spark lib package and default table data storage path.	No	User data is lost.
/user/omm-bulkload	Temporary directory	Stores HBase batch import tools temporarily.	No	Failed to import HBase tasks in batches.
/user/hbase	Temporary directory	Stores HBase batch import tools temporarily.	No	Failed to import HBase tasks in batches.
/sparkJobHistory	Fixed directory	Stores Spark event log data.	No	The History Server service is unavailable, and the task fails to be executed.
/flume	Fixed directory	Stores data collected by Flume from HDFS.	No	Flume runs improperly.
/mr-history/tmp	Fixed directory	Stores logs generated by MapReduce jobs.	Yes	Log information is lost.
/mr-history/done	Fixed directory	Stores logs managed by MR JobHistory Server.	Yes	Log information is lost.
/tenant	Created when a tenant is added.	Directory of a tenant in the HDFS. By default, the system automatically creates a folder in the /tenant directory based on the tenant name. For example, the default HDFS storage directory for ta1 is tenant/ta1. When a tenant is created for the first time, the system creates the /tenant directory in the HDFS root directory. You can customize the storage path.	No	The tenant account is unavailable.
/apps{1~5}/	Fixed directory	Stores the Hive package used by WebHCat.	No	Failed to run the WebHCat tasks.
/hbase	Fixed directory	Stores HBase data.	No	HBase user data is lost.
/hbaseFileStream	Fixed directory	Stores HFS files.	No	The HFS file is lost and cannot be restored.
/ats/active	Fixed directory	HDFS path used to store the timeline data of running applications.	No	Failed to run the tez task after the directory deletion.
/ats/done	Fixed directory	HDFS path used to store the timeline data of completed applications.	No	Automatically created after the deletion.
/flink	Fixed directory	Stores the checkpoint task data.	No	Failed to run tasks after the deletion.

**Table 2** Directory structure of the HDFS file system (applicable to MRS 3.x or later)
Path	Type	Function	Whether the Directory Can Be Deleted	Deletion Consequence
/tmp/spark2x/sparkhive-scratch	Fixed directory	Stores temporary files of metastore session in Spark2x JDBCServer.	No	Failed to run the task.
/tmp/sparkhive-scratch	Fixed directory	Stores temporary files of metastore sessions that are executed in CLI mode using Spark2x CLI.	No	Failed to run the task.
/tmp/logs/	Fixed directory	Stores container log files.	Yes	Container log files cannot be viewed.
/tmp/carbon/	Fixed directory	Stores the abnormal data in this directory if abnormal CarbonData data exists during data import.	Yes	Error data is lost.
/tmp/Loader-${Job name}_${MR job ID}	Temporary directory	Stores the region information about Loader HBase bulkload jobs. The data is automatically deleted after the job running is completed.	No	Failed to run the Loader HBase Bulkload job.
/tmp/hadoop-omm/yarn/system/rmstore	Fixed directory	Stores the ResourceManager running information.	Yes	Status information is lost after ResourceManager is restarted.
/tmp/archived	Fixed directory	Archives the MR task logs on HDFS.	Yes	MR task logs are lost.
/tmp/hadoop-yarn/staging	Fixed directory	Stores the run logs, summary information, and configuration attributes of ApplicationMaster running jobs.	No	Services are running improperly.
/tmp/hadoop-yarn/staging/history/done_intermediate	Fixed directory	Stores temporary files in the /tmp/hadoop-yarn/staging directory after all tasks are executed.	No	MR task logs are lost.
/tmp/hadoop-yarn/staging/history/done	Fixed directory	The periodic scanning thread periodically moves the done_intermediate log file to the done directory.	No	MR task logs are lost.
/tmp/mr-history	Fixed directory	Stores the historical record files that are pre-loaded.	No	Historical MR task log data is lost.
/tmp/hive-scratch	Fixed directory	Stores temporary data (such as session information) generated during Hive running.	No	Failed to run the current task.
/user/{user}/.sparkStaging	Fixed directory	Stores temporary files of the SparkJDBCServer application.	No	Failed to start the executor.
/user/spark2x/jars	Fixed directory	Stores running dependency packages of the Spark2x executor.	No	Failed to start the executor.
/user/loader	Fixed directory	Stores dirty data of Loader jobs and data of HBase jobs.	No	Failed to execute the HBase job. Or dirty data is lost.
/user/loader/etl_dirty_data_dir
/user/loader/etl_hbase_putlist_tmp
/user/loader/etl_hbase_tmp
/user/oozie	Fixed directory	Stores dependent libraries required for Oozie running, which needs to be manually uploaded.	No	Failed to schedule Oozie.
/user/mapred/hadoop-mapreduce-3.1.1.tar.gz	Fixed files	Stores JAR files used by the distributed MR cache.	No	The MR distributed cache function is unavailable.
/user/hive	Fixed directory	Stores Hive-related data by default, including the depended Spark lib package and default table data storage path.	No	User data is lost.
/user/omm-bulkload	Temporary directory	Stores HBase batch import tools temporarily.	No	Failed to import HBase tasks in batches.
/user/hbase	Temporary directory	Stores HBase batch import tools temporarily.	No	Failed to import HBase tasks in batches.
/spark2xJobHistory2x	Fixed directory	Stores Spark2x eventlog data.	No	The History Server service is unavailable, and the task fails to be executed.
/flume	Fixed directory	Stores data collected by Flume from HDFS.	No	Flume runs improperly.
/mr-history/tmp	Fixed directory	Stores logs generated by MapReduce jobs.	Yes	Log information is lost.
/mr-history/done	Fixed directory	Stores logs managed by MR JobHistory Server.	Yes	Log information is lost.
/tenant	Created when a tenant is added.	Directory of a tenant in the HDFS. By default, the system automatically creates a folder in the /tenant directory based on the tenant name. For example, the default HDFS storage directory for ta1 is tenant/ta1. When a tenant is created for the first time, the system creates the /tenant directory in the HDFS root directory. You can customize the storage path.	No	The tenant account is unavailable.
/apps{1~5}/	Fixed directory	Stores the Hive package used by WebHCat.	No	Failed to run the WebHCat tasks.
/hbase	Fixed directory	Stores HBase data.	No	HBase user data is lost.
/hbaseFileStream	Fixed directory	Stores HFS files.	No	The HFS file is lost and cannot be restored.