Cluster Administration
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NAS 4000s and 9000s Administration Guide
Virtual Servers
A virtual server is a cluster group that consists of a static IP Address resource and a Network
Name resource. Several virtual servers can be created. By assigning ownership of the virtual
servers to the different server nodes, the processing load on the NAS devices can be distributed
between the nodes of a cluster.
The creation of a virtual server allows resources dependant on the virtual server to fail over
and fail back between the cluster nodes. File Share and physical disks resources are assigned
to the virtual server to ensure non disruptive service of file shares to the clients.
Failover
Failover of cluster groups and resources happens:
■
when a node hosting the group becomes inactive. A shutdown of cluster service or a loss
of power can cause a failover.
■
when all of the resources within the group are dependent on one resource and that resource
fails.
■
when an administrator forces a failover.
A resource and all of its dependencies must be located in the same group so that if a resource
fails over, all of its dependent resources fail over.
When a resource is failed over, the cluster service performs certain procedures. First, all of the
resources are taken offline in an order defined by the resource dependencies. Secondly, the
cluster service attempts to transfer the group to the next node on the preferred owners list. If
the transfer is successful, the resources are brought online in accordance with the resource
dependency structure.
The system failover policy defines how the cluster detects and responds to the failure of
individual resources in the group. After a failover occurs and the cluster is brought back to its
original state, failback can occur automatically based on the policy. After a previously failed
node comes online, the cluster service can fail back the groups to the original host. The
failback policy must be set before the failover occurs so that failback works as intended.
Quorum Disk
Each cluster must have a shared disk called the Quorum disk. This physical disk in the
common cluster disk array plays a critical role in cluster operations. The Quorum disk offers a
means of persistent storage. The disk must provide physical storage that can be accessed by
any node in the cluster. If a node has control of the quorum resource upon startup, it can
initiate the cluster. In addition, if the node can communicate with the node that owns the
quorum resource, it can join or remain in the cluster.
The Quorum disk maintains data integrity by:
■
storing the most current version of the cluster database.
■
guaranteeing that only one set of active communicating nodes is allowed to operate as a
cluster.
Содержание NAS 4000s
Страница 18: ...About this Guide 18 NAS 4000s and 9000s Administration Guide ...
Страница 50: ...Basic Administrative Procedures and Setup Completion 50 NAS 4000s and 9000s Administration Guide ...
Страница 92: ...Disk Management 92 NAS 4000s and 9000s Administration Guide ...
Страница 196: ...NetWare File System Management 196 NAS 4000s and 9000s Administration Guide ...
Страница 246: ...Index 246 NAS 4000s and 9000s Administration Guide ...