It's a self-help answer. The solution I solved is as follows. Note, I don't know if this is the right way. 1. Reinstall hdfs 2. Set up a different data directory than before 3. Verify that it runs normally 4. Change the data directory to the old path 5. hdfs restart 6. hdfs fall into safe mode, but data that existed in hdfs could be queried 7. Download the data to the local space using the 'copyToLocal' command 8. Afterwards, restore by transferring to the newly installed data directory ... View more