PowerScale OneFS 9.8.0.0 Web Administration Guide

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On-disk identity

After the user mapper resolves a user's identity, OneFS determines an authoritative identifier for it, which is the preferred on-disk identity.

OnesFS stores either UNIX or Windows identities in file metadata on disk. On-disk identity types are UNIX, SID, and native. Identities are set when a file is created or a access control data for a file is modified. Almost all protocols require some level of mapping to operate correctly, so choosing the preferred identity to store on disk is important. You can configure OneFS to store either the UNIX or the Windows identity, or you can allow OneFS to determine the optimal identity to store.

On-disk identity types are UNIX, SID, and native. Although you can change the type of on-disk identity, the native identity is best for a network with UNIX and Windows systems. In native on-disk identity mode, setting the UID as the on-disk identity improves NFS performance.

NOTE:The SID on-disk identity is for a homogeneous network of Windows systems that are managed only with Active Directory. When you upgrade, the on-disk identity setting is preserved. On new installations, the on-disk identity is set to native.

The native on-disk identity type allows the OneFS authentication daemon to select the correct identity to store on disk by checking for the identity mapping types in the following order:

Table 1. Ordered Identity Mapping TypesThe following table displays the description and order for each mapping type.
Order	Mapping type	Description
1	Algorithmic mapping	An SID that matches S-1-22-1-UID or S-1-22-2-GID in the internal ID mapping database is converted back to the corresponding UNIX identity, and the UID and GID are set as the on-disk identity.
2	External mapping	A user with an explicit UID and GID defined in a directory service (such as Active Directory with RFC 2307 attributes, LDAP, NIS, or the OneFS file provider or local provider) has the UNIX identity set as the on-disk identity.
3	Persistent mapping	Mappings are stored persistently in the identity mapper database. An identity with a persistent mapping in the identity mapper database uses the destination of that mapping as the on-disk identity, which occurs primarily with manual ID mappings. For example, if there is an ID mapping of GID:10000 to S-1-5-32-545, a request for the on-disk storage of GID:10000 returns S-1-5-32-545.
4	No mapping	If a user lacks a UID or GID even after querying the other directory services and identity databases, its SID is set as the on-disk identity. In addition, to ensure that a user can access files over NFS, OneFS allocates a UID and GID from a preset range of 1,000,000–2,000,000. In native on-disk identity mode, a UID or GID that OneFS generates is never set as the on-disk identity.

NOTE:If you change the on-disk identity type, you should run the PermissionRepair job with the Convert repair type selected to make sure that the disk representation of all files is consistent with the changed setting. For more information, see the Run the PermissionRepair job section.