WHAT IS CEPHFS
- CephFS is a POSIX file system that can be accessed by multiple clients
- Mounted directly via the Linux kernel or via FUSE and libcephfs
- Metadata (file names, directory contents, permissions, …) and data kept in seperate pools
- Metadata is handled by an MDS (Metadata Server)
- Clients connect directly to OSDs to store/retrieve data.
METADATA SERVERS (MDS)
MDS are required to get started with CephFS.
HOW MANY MDS?
- Each file system can have any number of active MDS
- Each active MDS will need a separate passive failover MDS to take over
- For most cases one active MDS and one standby MDS is sufficient
- Multiple active MDS are typically used once you have > 100 million files…
- …and a larger number of metadata operations or open files
SETTING UP MDS
- Navigate to http://[hostname|ip-address]:8080/services
- Press + MDS in the action bar at the bottom of your window
- Select at least two servers to use (1 active + 1 standby)
MORE THAN ONE ACTIVE MDS
Per default, there will always be only one active MDS. If you really do need more, you will have to set that manually.
- Navigate to http://[hostname|ip-address]:8080/maintenance/terminal
- or connect to the management node per SSH if you prefer
- enter the following
ceph fs set cephfs max_mds 2
Now you can test your CephFS with our built in CephFS Explorer: http://[hostname|ip-address]:8080/cephfs. You can move, copy and delete files like in any other file explorer by using the usual shortcuts.
Learn how to setup NFS access here.