CephFS provides a POSIX-compliant filesystem on top of RADOS. It uses the MDS daemon, which manages its metadata and keeps it separated from the data, which helps in reduced complexity and improves reliability. CephFS inherits features from RADOS and provides dynamic rebalancing for data.

libcephfs libraries play an important role in supporting its multiple client implementations. It has native Linux kernel driver support, thus clients can use native filesystem mounting using the mount command. It has a tight integration with SAMBA and support for CIFS and SMB. CephFS extends its support to filesystems in userspace (FUSE) using the cephfuse modules. It also allows direct application interaction, with the RADOS cluster using libcephfs libraries.

CephFS is getting popular as a replacement for Hadoop HDFS. HDFS has a single name node, which impacts its scalability and creates a single point of failure. Unlike HDFS, CephFS can be implemented over multiple MDSes in an active-active state, thus making it highly scalable and high performing with no single point of failure. In the upcoming chapters, we will focus on implementing CephFS.