Dell SAS Cluster Configuration Support Matrices
- PowerEdge Cluster with PowerVault MD3200/MD3220 Array - The PowerEdge Cluster with PowerVault MD3200/MD3220 Array is a Serial Attached SCSI (SAS) solution with up to 4 homogeneous Dell PowerEdge servers, Dell PowerVault MD3200/MD3220 storage system with SAS or Solid State Drives (SSD), and Dell SAS 6Gbps HBA in a Microsoft Cluster configuration.
- PowerEdge Cluster with PowerVault MD3000 Array - The PowerEdge Cluster with PowerVault MD3000 Array is a Serial Attached SCSI (SAS) solution with 2 homogeneous Dell PowerEdge servers, Dell PowerVault MD3000 storage system with SAS/SATA drives, and Dell SAS 5E HBA in a Microsoft Cluster configuration.
SAS Cluster Overview
A PowerEdgeTM SAS Cluster is an integrated system of components, including a pair of PowerEdge servers, PowerVault MD3000 storage system, a cluster interconnect, and Microsoft's failover cluster software. Microsoft® Windows® 2003 Enterprise Edition Cluster Service implements two-node failover clustering that delivers high availability for applications and services. Optional features of a PowerEdge SAS Cluster include advanced cluster management software, Dell OpenManageTM 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 sit 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.
Each cluster node attaches to the storage system using one SAS cable. In this configuration, there is only one storage path from the cluster node to the storage system. If a component fails in the storage path such as the Host Bus Adapter (HBA), the cable, or the storage controller, the cluster failover can occur; MSCS moves the cluster group to the other server and accesses the data through the other server.
NOTE: A Non-Redundant Direct-Attached configuration is supported with single-controller specifically with MD3000. In this configuration, there is only a single data path from a host to the MD3000 controller. This configuration does not offer high-availability within the storage system, and is not recommended for applications that need critical data storage.
Each cluster node attaches to the storage system using two SAS 5/E HBAs and two SAS cables. In this configuration, there are redundant storage paths from the cluster node to the storage system. If a component fails in the storage path such as the HBA, the cable, or the storage controller, the multi-path software automatically reroutes the I/O requests to the alternate path so that the storage array continues to operate without interruption.
NOTE: This figure used for illustration purpose only. For actual supported hardware configuration information, please refer to the online documentation for the PowerEdge SAS Clusters.