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| -rw-r--r-- | Documentation/admin-guide/nfs/pnfs-block-server.rst | 42 |
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diff --git a/Documentation/admin-guide/nfs/pnfs-block-server.rst b/Documentation/admin-guide/nfs/pnfs-block-server.rst new file mode 100644 index 0000000000..20fe9f5117 --- /dev/null +++ b/Documentation/admin-guide/nfs/pnfs-block-server.rst @@ -0,0 +1,42 @@ +=================================== +pNFS block layout server user guide +=================================== + +The Linux NFS server now supports the pNFS block layout extension. In this +case the NFS server acts as Metadata Server (MDS) for pNFS, which in addition +to handling all the metadata access to the NFS export also hands out layouts +to the clients to directly access the underlying block devices that are +shared with the client. + +To use pNFS block layouts with the Linux NFS server the exported file +system needs to support the pNFS block layouts (currently just XFS), and the +file system must sit on shared storage (typically iSCSI) that is accessible +to the clients in addition to the MDS. As of now the file system needs to +sit directly on the exported volume, striping or concatenation of +volumes on the MDS and clients is not supported yet. + +On the server, pNFS block volume support is automatically if the file system +support it. On the client make sure the kernel has the CONFIG_PNFS_BLOCK +option enabled, the blkmapd daemon from nfs-utils is running, and the +file system is mounted using the NFSv4.1 protocol version (mount -o vers=4.1). + +If the nfsd server needs to fence a non-responding client it calls +/sbin/nfsd-recall-failed with the first argument set to the IP address of +the client, and the second argument set to the device node without the /dev +prefix for the file system to be fenced. Below is an example file that shows +how to translate the device into a serial number from SCSI EVPD 0x80:: + + cat > /sbin/nfsd-recall-failed << EOF + +.. code-block:: sh + + #!/bin/sh + + CLIENT="$1" + DEV="/dev/$2" + EVPD=`sg_inq --page=0x80 ${DEV} | \ + grep "Unit serial number:" | \ + awk -F ': ' '{print $2}'` + + echo "fencing client ${CLIENT} serial ${EVPD}" >> /var/log/pnfsd-fence.log + EOF |