1 2pNFS SCSI layout server user guide 3================================== 4 5This document describes support for pNFS SCSI layouts in the Linux NFS server. 6With pNFS SCSI layouts, the NFS server acts as Metadata Server (MDS) for pNFS, 7which in addition to handling all the metadata access to the NFS export, 8also hands out layouts to the clients so that they can directly access the 9underlying SCSI LUNs that are shared with the client. 10 11To use pNFS SCSI layouts with with the Linux NFS server, the exported file 12system needs to support the pNFS SCSI layouts (currently just XFS), and the 13file system must sit on a SCSI LUN that is accessible to the clients in 14addition to the MDS. As of now the file system needs to sit directly on the 15exported LUN, striping or concatenation of LUNs on the MDS and clients 16is not supported yet. 17 18On a server built with CONFIG_NFSD_SCSI, the pNFS SCSI volume support is 19automatically enabled if the file system is exported using the "pnfs" 20option and the underlying SCSI device support persistent reservations. 21On the client make sure the kernel has the CONFIG_PNFS_BLOCK option 22enabled, and the file system is mounted using the NFSv4.1 protocol 23version (mount -o vers=4.1). 24
