Resource and Resource Group States and Settings
A system administrator applies static settings to resources and resource groups. You can change these settings only by administrative action. The RGM moves resource groups between dynamic states. These settings and states are as follows Managed or unmanaged settings. These cluster-wide settings apply only to resource groups. The RGM manages resource groups. You can use the clresourcegroup command to request that the RGM manage or unmanage a resource group. These resource group settings do not...
Device Groups
In the Sun Cluster software, all multihost devices must be under control of the Sun Cluster software. You first create volume manager disk groups, either Solaris Volume Manager disk sets or VERITAS Volume Manager disk groups, on the multihost disks. Then, you register the volume manager disk groups as device groups. A device group is a type of global device. In addition, the Sun Cluster software automatically creates a raw device group for each disk and tape device in the cluster. However,...
Cluster Membership Monitor
To ensure that data is kept safe from corruption, all nodes must reach a consistent agreement on the cluster membership. When necessary, the CMM coordinates a cluster reconfiguration of cluster services applications in response to a failure. The CMM receives information about connectivity to other nodes from the cluster transport layer. The CMM uses the cluster interconnect to exchange state information during a reconfiguration. After detecting a change in cluster membership, the CMM performs a...
Using the Cluster Interconnect for Data Service Traffic
A cluster must have multiple network connections between nodes, forming the cluster interconnect. Sun Cluster software uses multiple interconnects to achieve the following goals For both internal and external traffic such as file system data or scalable services data, messages are striped across all available interconnects. The cluster interconnect is also available to applications, for highly available communication between nodes. For example, a distributed application might have components...
Failback Settings
Resource groups fail over from one node or zone to another. When this failover occurs, the original secondary becomes the new primary. The failback settings specify the actions that occur when the original primary comes back online. The options are to have the original primary become the primary again failback or to allow the current primary to remain. You specify the option you want by using the Failback resource group property setting. If the original node or zone that hosts the resource...
File Systems FAQs
Question Can I run one or more of the cluster nodes as highly available NFS servers with other cluster nodes as clients Answer No, do not do a loopbackmount. Question Can I use a cluster file system for applications that are not under Resource Group Manager control Answer Yes. However, without RGM control, the applications need to be restarted manually after the failure of the node or zone on which they are running. Question Must all cluster file systems have a mount point under the global...
Using Cluster File Systems
In the Sun Cluster software, all multihost disks are placed into device groups, which can be Solaris Volume Manager disk sets, VxVM disk groups, or individual disks that are not under control of a software-based volume manager. For a cluster file system to be highly available, the underlying disk storage must be connected to more than one node. Therefore, a local file system a file system that is stored on a node's local disk that is made into a cluster file system is not highly available. You...
Support for Solaris Zones on Sun Cluster Nodes Directly Through the RGM
On a cluster where the Solaris 10 OS is running, you can configure a resource group to run in the global zone or in non-global zones. The RGM manages each zone as a switchover target. If a non-global zone is specified in the node list of a resource group, the RGM brings the resource group online in the specified zone on the node. Figure 3-8 illustrates the failover of resource groups between zones on Sun Cluster nodes in a two-node cluster. In this example, identical zones are configured on...
Failfast Mechanism
The failfast mechanism detects a critical problem in either the global zone or in a non-global zone on a node. The action that Sun Cluster takes when failfast detects a problem depends on whether the problem occurs in the global zone or a non-global zone. If the critical problem is located in the global zone, Sun Cluster forcibly shuts down the node. Sun Cluster then removes the node from cluster membership. Ifthe critical problem is located in a non-global zone, Sun Cluster reboots that...
About Failure Fencing
A major issue for clusters is a failure that causes the cluster to become partitioned called split brain . When split brain occurs, not all nodes can communicate, so individual nodes or subsets of nodes might try to form individual or subset clusters. Each subset or partition might believe it has sole access and ownership to the multihost devices. When multiple nodes attempt to write to the disks, data corruption can occur. Failure fencing limits node access to multihost devices by physically...
Cluster Nodes
A cluster node is a machine that is running both the Solaris Operating System and the Sun Cluster software. A cluster node is either a current member of the cluster a cluster member or a potential member. SPARC Sun Cluster software supports from one to sixteen nodes in a cluster. Different hardware configurations impose additional limits on the maximum number of nodes that you can configure in a cluster composed of SPARC based systems. See SPARC Sun Cluster Topologies for SPARC on page 27 for...
Data Service Project Configuration
Data services can be configured to launch under a Solaris project name when brought online by using the RGM. The configuration associates a resource or resource group managed by the RGM with a Solaris project ID. The mapping from your resource or resource group to a project ID gives you the ability to use sophisticated controls that are available in the Solaris OS to manage workloads and consumption within your cluster. Note - You can perform this configuration if you are using Sun Cluster on...
Monitoring Disk Paths
This section describes two methods for monitoring disk paths in your cluster. The first method is provided by the cldevice command. Use this command to monitor, unmonitor, or display the status of disk paths in your cluster. You can also use this command to print a list of faulted disks and to monitor disk paths from a file. See the cldevice lCL man page. The second method for monitoring disk paths in your cluster is provided by the Sun Cluster Manager, formerly SunPlex Manager, graphical user...
Global Devices
The Sun Cluster software uses global devices to provide cluster-wide, highly available access to any device in a cluster, from any node, without regard to where the device is physically attached. In general, if a node fails while providing access to a global device, the Sun Cluster software automatically discovers another path to the device. The Sun Cluster software then redirects the access to that path. Sun Cluster global devices include disks, CD-ROMs, and tapes. However, the only...