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Lustre 1.6 Operations Manual

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CHAPTER 16<br />

POSIX<br />

This chapter describes POSIX and includes the following sections:<br />

■<br />

■<br />

■<br />

Installing POSIX<br />

Running POSIX Tests Against <strong>Lustre</strong><br />

Isolating and Debugging Failures<br />

Portable Operating System Interface (POSIX) is a set of standard, operating system<br />

interfaces based on the Unix OS. POSIX defines filesystem behavior on single Unix<br />

node. It is not a standard for clusters.<br />

POSIX specifies the user and software interfaces to the OS. Required program-level<br />

services include basic I/O (file, terminal, and network) services. POSIX also defines<br />

a standard threading library API which is supported by most modern operating<br />

systems.<br />

POSIX in a cluster means that most of the operations are atomic. Clients can not see<br />

the metadata. POSIX offers strict mandatory locking which gives guarantee of<br />

semantics. Users do not have control on these locks.<br />

The current <strong>Lustre</strong> POSIX is comparable with NFS. <strong>Lustre</strong> 1.8 promises strong<br />

security with features like GSS/Kerberos 5. This enables graceful handling of users<br />

from multiple realms which, in turn, introduce multiple UID and GID databases.<br />

Note – Advisory fcntl/flock/lockf locks will be available in <strong>Lustre</strong> 1.8.<br />

Note – Although used mainly with UNIX systems, the POSIX standard can apply to<br />

any operating system.<br />

16-1

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