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