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 UID Mapping for GPFS in a Multi-cluster Environment
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| This document describes a solution to the problem of handling user and group IDs in GPFS in a multi–cluster environment. We use the term ”multi-cluster environment“ to describe a setup where several independent GPFS clusters exist, possibly managed by separate organizations, and an ability to mount a GPFS file system across clusters is desired. The specific set of challenges covered here arise from the fact that the user ID (UID) and group ID (GID) space is normally unique to a particular cluster. While a user may have an account on several clusters, this account may have a different set of UIDs/GIDs in every cluster. Rather than implementing and deploying a separate, GPFS-specific, global infrastructure for managing user IDs, names, and accounts, this document describes an interface that allows GPFS to integrate into an existing user registry infrastructure, such as the Globus Security Infrastructure (GSI) used by TeraGrid. The interface is based on a set of user-supplied ID remapping helper functions (IRHF) for performing dynamic UID/GID remapping in GPFS code as transparently as possible to the end user. The goal is to allow users to access a remotely mounted (i.e. mounted from a cluster other than the one where the file system was created) GPFS file system much like a local GPFS file system, without taking a large performance hit due to the extra work involved in UID/GID remapping. |
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