Filesystem requirements

The Hadoop Distributed File System (HDFS) is designed to operate on top of the underlying file system in the operating system. The following operating systems are supported:

If you are choosing between ext3 and ext4, ext4 is recommended.

Linux file systems store metadata that records when each file was accessed. It means that each read operation also writes to the disk. Disable this functionality to speed up file reads. To do this, add the noatime mount option to each line that addresses a file system in the /etc/fstab file, for example:

Use the following command to apply changes without rebooting:

UNIX-based systems use umask (user file-creation mode mask) to set default permissions for created files and directories. In most Linux distributions, the umask default value is 0022 (022) or 0002 (002). The basic rights for a directory are 0777 (rwxrwxrwx), and for a file — 0666 (rw-rw-rw). Subtract umask from basic rights to determine rights when umask is applied. The default umask 0002 is used for an ordinary user. With this mask, the default rights for a directory are 775, and for a file 664. For the superuser (root), the default umask is 0022. With this mask, the default rights for a directory are 755, and for a file 644.

You can set umask in the etc/bashrc or /etc/profile file.

ADH supports umask values listed in the table below.