Lustre Software Components and Node Types

Lustre file system components and nodes.

The following Lustre software components can be implemented on selected nodes of the Cray system running CLE 6.0 UP05.

Clients

Services or programs that access the file system. On Cray systems, clients are typically associated with login or compute nodes.

LNet Routers

Transfers LNet traffic between Lustre servers and Lustre clients that are on different networks. On Cray systems, LNet routers are typically used to connect external Lustre file systems on InfiniBand (IB) networks to the HSN.

Object Storage Target (OST)

Software interface to back-end storage volumes. There may be one or more OSTs. The client performs parallel I/O operations across multiple OSTs.

Object Storage Server (OSS)

Node that hosts the OSTs. Each OSS node is referenced by node ID (NID) and provides a Fibre Channel or IB connection to a RAID controller. The OST is a logical device; the OSS is the physical node.

Metadata Server (MDS)

Owns and manages information about the files in the Lustre file system. Handles namespace operations such as file creation, but does not contain any file data. Stores information about which file is located on which OSTs, how the blocks of files are striped across the OSTs, the date and time the file was modified, and so on. The MDS is consulted whenever a file is opened or closed. Because file namespace operations are done by the MDS, they do not impact operations that manipulate file data.

Metadata Target (MDT)

Software interface to back-end storage volumes for the MDS. Stores metadata for the Lustre file system.

Management Server (MGS)

Controls the configuration information for all Lustre file systems running at a site. Clients and servers contact the MGS to retrieve or change configuration information.