In production environment, we always have scenario like this, we want to backup files on hdfs for some time and then hope to delete these files automatically. For example, we keep only 1 day's logs on local disk due to limited disk space, but we need to keep about 1 month's logs in order to debug program bugs, so we keep all the logs on hdfs and delete logs which are older than 1 month. This is a typical scenario of HDFS TTL. So here we propose that hdfs can support TTL.
Following are some details of this proposal:
1. HDFS can support TTL on a specified file or directory
2. If a TTL is set on a file, the file will be deleted automatically after the TTL is expired
3. If a TTL is set on a directory, the child files and directories will be deleted automatically after the TTL is expired
4. The child file/directory's TTL configuration should override its parent directory's
5. A global configuration is needed to configure that whether the deleted files/directories should go to the trash or not
6. A global configuration is needed to configure that whether a directory with TTL should be deleted when it is emptied by TTL mechanism or not.