Orphaned Lnodes

An orphaned lnode is one that has a nonexistent parent lnode. This is of concern to an administrator because Solaris Resource Manager prevents processes from attaching to any lnode that is orphaned or has an orphaned ancestor in the scheduling tree.

The kernel checks changes to the sgroup attribute in order to prevent the creation of orphans by invalid alterations to the scheduling group parent.

The major effect of an lnode being orphaned is that it can no longer have processes attached to it. Since no process can connect to it, the lnode cannot be used for logging in. Any attempts to log in using the corresponding account will fail.

The easiest way for an administrator to detect orphaned lnodes is to use the limreport command with the built-in orphan identifier. The command:

% limreport orphan - uid sgroup lname

will list the UID, scheduling group parent, and login name of users who have orphaned lnodes. The sgroup attribute can be used to determine which of the lnodes is at the top of an orphaned section of the tree.

The first step an administrator should take when an orphaned lnode is discovered is to find the top of the orphaned section of the scheduling tree, since this is the lnode that needs to be reattached. If the top of the orphaned section is not correctly identified, only part of the orphaned section will be reattached to the tree.

When the top of the orphaned section has been determined, an administrator with sufficient privilege can use limadm to set the sgroup attribute of the topmost orphaned lnode to a valid lnode within the scheduling tree. This will cause the orphaned lnode to be reattached to the tree as a member of the group that the valid lnode heads. limadm verifies that the new scheduling group parent to be applied is able to be activated, thus ensuring that the lnode being changed will no longer be orphaned.

Alternatively, the administrator can create a new user whose UID is equal to the UID in the sgroup attribute of the orphaned lnode. This will cause the automatic reattachment of the orphaned section of the tree.