A Client in the Lustre filesystem is a machine that requires data. This could be a computation, visualisation, or desktop node. Once mounted, a Client experiences the Lustre filesystem as if the filesystem were a local or NFS mount.
In the Lustre filesystem metadata requests are serviced by two components: the Metadata Server (MDS) an Metadata Target (MDT). Together, the MDS and MDT service requests like: Where is the file XYZ? I'm going to write to file ABC so prohibit anyone else from using it.
All a Client needs to mount a Lustre filesystem is the location of the MDS. Currently, each Lustre filesystem has only one active MDS. The MDS persists the filesystem metadata in the MDT.
Object Storage services
Data in the Lustre filesystem is stored and retrieved by two components: the Object Storage Server (OSS) and the Object Storage Target (OST). Together, the OSS and OST provide the data to the Client.
A Lustre filesystem can have one or more OSS. An OSS typically has between two and eight OSTs attached. To increase the storage of the Lustre filesystem, additional OSTs can be attached. To increase the bandwidth of the Lustre filesystem, additional OSS can be attached – provided the connection to the Client is not saturated.
Lustre includes additional services including LNET. LNET is designed to simplify configuration of a Lustre filesystem over complex network topologies.
A Lustre filesystem uses modified versions of e2fsprogs and tar. Managing a large Lustre filesystem is a task that is simplified by community and vendor supported tools. Details of these tools are available at the COMMUNITY PAGE OF THE WIKI
- Understanding Lustre Filesystem Internals white paper from National Centre for Computational Sciences.