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Fibre Channel Cluster
A PowerEdge Cluster is an integrated system of components, including PowerEdge servers, PowerVault or Dell | EMC® storage system(s), a cluster interconnect, and Microsoft's failover cluster software. Microsoft® Windows® 2000 Cluster Service implements two-node failover clustering that delivers high availability for applications and services. Microsoft Windows 2003 Enterprise Edition Cluster Service supports 2 to 8 node high availability clusters. Optional features of a PowerEdge Cluster include Dell OpenManage software, installation services, consulting services, and proof-of-concept testing.
Active/Active and Active/Passive Configurations
Microsoft Cluster Service (MSCS) and all PowerEdge Clusters support both active/active and active/passive cluster configurations. The term active/active refers to a cluster with at least one virtual server running on each node. For example, in a 2-node cluster configuration, when an application is running on Node 1, Node 2 does not need to remain idle waiting for Node 1 to fail. Node 2 can run its own cluster-aware applications (or another instance of the same application) while providing failover capabilities for resources on Node 1. Node 1 in turn can provide failover capabilities for resources on Node 2. An active/active cluster node must be sized appropriately to handle the load of both nodes (in the event of a failover).
The term active/passive refers to failover cluster configurations in which one or more cluster nodes is actively processing requests for cluster applications while at least one cluster node simply waits for an active node to fail. An active/passive configuration is more costly in terms of price/performance because one or more servers remain idle most of the time. It is appropriate for business-critical systems since the applications can use the full power of another server in case of a failure.
Direct Attach
A direct-attach PowerEdge Cluster configuration includes the two cluster nodes and a single storage system. In direct-attach configurations, the storage processors on the Dell | EMC storage system are connected directly to the Fibre Channel host bus adapters (HBAs) in the cluster nodes. A SAN is not required (see Figure 1).
Each clustered server has redundant and active paths to the storage system. The failover software running on each node monitors the paths to the storage system and can reroute traffic in the event of a failure in the HBA, cable system, or storage processor.
Figure 1
SAN-Attach
A PowerEdge Cluster can be integrated into a SAN (Storage Area Network) using Fibre Channel switches. SAN-attached clusters are superior to direct-attached cluster configurations in configuration, flexibility, and expandability. They also provide consolidated backups with the ability to share Fibre Channel tape devices among multiple clusters and standalone servers. SAN-attached configurations require a redundant Fibre Channel switch fabric.
If greater storage capacity is desired for the cluster, a SAN-attached cluster configuration can be connected to multiple storage systems through the SAN (see Figure 2 below).
Figure 2
Cluster consolidation is an extension of a SAN-attached cluster configuration. Both storage consolidation and cluster consolidation can help lower the total cost of ownership of a SAN. For a SAN, cluster consolidation is commonly defined as the ability to allow multiple clusters and stand-alone servers to access a portion of the storage capacity offered by one or more storage systems (see Figure 3).
In a Cluster Consolidation, EMC's Navisphere® Access Logix software performs Fibre Channel LUN mapping and masking to partition the storage system and assign each data volume to specific server(s) attached to the SAN. The Navisphere Access Logix software gives servers explicit ownership of a data volume located within the common enclosure. For example, if two clusters are sharing a storage system that has four available LUNs (or volumes of data), Cluster 1 can be assigned LUN 0 and 1, and Cluster 2 can be assigned LUN 2 and 3. The LUN masking software prevents each server or cluster from discovering or accessing storage owned by other server or cluster nodes.
Figure 3
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Latest page update: made by Bryant_Vo
, May 24 2007, 10:49 AM EDT
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| Started By | Thread Subject | Replies | Last Post | |
|---|---|---|---|---|
| brian_summers | Active/Active Cluster with SQL 05 | 1 | Jul 17 2008, 3:32 PM EDT by todd_muirhead | |
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Thread started: Jul 17 2008, 9:44 AM EDT
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Ah...I found the page :-)
Ok but now...per the info above "active/active" is a different concept than Oracle RAC...yes? i.e. Oracle RAC enables multiple nodes to read/write from the same volumes but MS Active/Active clustering does not?
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Keyword tags:
active/active
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