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Mounting and unmounting Lustre file systems on client nodes4–2

4.1 Overview

NOTE: Before you attempt to mount a Lustre file system on a client node, make sure that the node has been

configured as described in Chapter 2 or Chapter 3. In particular, the client node must have an options

lnet setting configured in the /etc/modprobe.conf.lustre or /etc/modules.conf.lustre

file.

A Lustre file system can be mounted using either the sfsmount(8) command (the recommended method)

or the standard mount(8) command with a file system type of lustre. This chapter describes the syntax

of the device field in the sfsmount and mount commands and the Lustre-specific mount options that are

available.

To mount a Lustre file system at boot time, the /etc/fstab file can be used. However, a problem with using

the /etc/fstab file is that the mount operations happen early in the boot sequence. If there is a syntax

error in the mount directive or an HP SFS server is down, the boot will hang. At that point, you will be unable

to log into the node to diagnose the problem. For this reason, HP SFS provides the SFS service. The SFS

service starts later in the boot sequence and uses an /etc/sfstab.proto or

/etc/sfstab file to describe the Lustre file systems that are to be mounted at boot time. In addition, the

SFS service uses the sfsmount command instead of the standard mount command.

The SFS service and associated sfsmount command provide the following additional features that are not

available with the /etc/fstab file and the standard mount command:

• The SFS service starts after the sshd(8) daemon; this allows you to log in and diagnose problems

even if a mount operation hangs.

• The SFS service supports mounting in the background using the /jointfilesconvert/261981/bg mount option.

• If the Lustre file system or HP SFS server is temporarily stopped or down, the mount operation normally

fails. However, when used by the SFS service, the sfsmount command continues to retry the mount

operation until the file system or the HP SFS server is restarted. This feature, which is controlled by the

[no]repeat mount option, means that when a node boots you are guaranteed that all Lustre file

systems are correctly mounted and available to your applications.

• The sfsmount command supports a number of additional mount options to control client caching

and the remote procedure call (RPC) communication mechanism between a client node and the HP

SFS server.

• The SFS service allows you to have a common /etc/sfstab.proto file. When started, the SFS

service generates a local /etc/sfstab file from the /etc/sfstab.proto. This allows you to

mount different file systems, or use different mount options, on different nodes.

The syntax of the device field in the sfsmount and mount commands is quite complex—for example:

lnet://10.0.128.2@vib0:/south-mds3/client_vib

For convenience, the sfsmount command also supports an optional http: mount protocol. With this

syntax, you specify the name of the server and the name of the file system. The syntax for this is simpler and

more intuitive—for example:

http://south/data

The http: protocol is normally used when running the sfsmount command interactively—it must not be

used to mount file systems on large numbers of client nodes at the same time.

The mount methods described so far use the zeroconf feature of the Lustre file system. This feature is based

on the LNET communication mechanism in Lustre. In this chapter and in other chapters in this guide, this

mechanism is referred to as the lnet: protocol. In previous releases of the HP SFS software, LNET was not

present and the mount(8) command was not used. Instead, the lconf command was used to load the

appropriate Lustre modules and mount the file systems. To support backwards compatibility, the sfsmount

command continues to support the original syntax using the ldap: protocol. In the next major release of

HP SFS, the lconf command and the associated ldap: protocol will not be supported. HP recommends

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