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0002 ==================================
0003 pNFS SCSI layout server user guide
0004 ==================================
0005
0006 This document describes support for pNFS SCSI layouts in the Linux NFS server.
0007 With pNFS SCSI layouts, the NFS server acts as Metadata Server (MDS) for pNFS,
0008 which in addition to handling all the metadata access to the NFS export,
0009 also hands out layouts to the clients so that they can directly access the
0010 underlying SCSI LUNs that are shared with the client.
0011
0012 To use pNFS SCSI layouts with the Linux NFS server, the exported file
0013 system needs to support the pNFS SCSI layouts (currently just XFS), and the
0014 file system must sit on a SCSI LUN that is accessible to the clients in
0015 addition to the MDS. As of now the file system needs to sit directly on the
0016 exported LUN, striping or concatenation of LUNs on the MDS and clients
0017 is not supported yet.
0018
0019 On a server built with CONFIG_NFSD_SCSI, the pNFS SCSI volume support is
0020 automatically enabled if the file system is exported using the "pnfs"
0021 option and the underlying SCSI device support persistent reservations.
0022 On the client make sure the kernel has the CONFIG_PNFS_BLOCK option
0023 enabled, and the file system is mounted using the NFSv4.1 protocol
0024 version (mount -o vers=4.1).
