Setting HDFS quotas

As an administrator, you can set up HDFS quotas for the number of file and directory names used and the amount of space used by directories.

Considerations for working with HDFS quotas

The quotas for names and the quotas for space are independent of each other.
You cannot create more files and directories if their creation would cause the quotas to exceed.
Block allocation fails if the quota prevents a full block from being written.
If you are using replication, each replica of a block counts against the quota.

The file count quota is a limit on the number of file and directory names in the directory configured.
A directory counts against its own quota. Therefore, a quota value of 1 forces the directory to remain empty.
File counts are based on the intended replication factor for the files. Changing the replication factor for a file will increase or decrease the corresponding quota values.

The space quota is a hard limit on the number of bytes used by files in the tree rooted at the directory being configured.
Each replica of a block counts against the quota.
The disk space quota calculation takes replication into account. Therefore, the calculation uses the replicated size of each file and not the user-facing size.
The disk space quota calculation includes open files (that are being written) and files that already written.
Block allocations for files being written fail if the quota does not allow a full block to be written.