Lazy Update has some limitations, which you need to consider when you rely on Lazy Update in general:
•If the first disk in a sharedvg has been replaced, the importvg command will fail as Lazy Update expects to be able to match the hdisk number for the first disk to a valid PVID in the ODM.
•Multi-LUN support on the SCSI RAID cabinets can be very confusing to Lazy Update as each LUN appears as a new hdisk known to only one node in the cluster (remember that Lazy Update works on LVM constructs).
8.4.3C-SPOC
The Cluster Single Point of Control (C-SPOC) utility lets system administrators perform administrative tasks on all cluster nodes from any node in the cluster. These tasks are based on commonly performed AIX system administration commands that let you:
•Maintain user and group accounts (see 8.8, “User Management” on page 178).
•Maintain shared Logical Volume Manager (LVM) components.
•Control HACMP services on a cluster-wide basis (see Chapter 8.2, “Starting and Stopping HACMP on a Node or a Client” on page 154).
Without C-SPOC functionality, the system administrator must spend time executing administrative tasks individually on each cluster node. Using the C-SPOC utility, a command executed on one node is also executed on other cluster nodes. Thus C-SPOC minimizes administrative overhead and reduces the possibility of inconsistent node states. For example, to add a user, you usually must perform this task on each cluster node. Using C-SPOC, however, you issue a C-SPOC command once on a single node, and the user is added to all specified cluster nodes.
C-SPOC also makes managing logical volume components and controlling cluster services more efficient. You can use the C-SPOC utility to start or stop cluster services on nodes from a single node.
C-SPOC provides this functionality through its own set of cluster administration commands, accessible through SMIT menus and screens. To use C-SPOC, select the Cluster System Management option from the HACMP for AIX menu. See the HACMP for AIX, Version 4.3: Administration Guide, SC23-4279for detailed information on using C-SPOC SMIT options.
With C-SPOC, you can perform the following tasks:
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