High Availability / Dual Domain Information - HP P2000 Deployment Manual

4 High availability / dual domain information

HP External SAS BladeSystem Solutions provide high availability, offering c-Class BladeSystem
users full connectivity to External SAS storage by using the following redundant hardware
components:
Two controllers in each external shared SAS storage enclosure
Two SAS BL Switches in the BladeSystem c-Class enclosure interconnect row
One or two P71 1m/P712m controllers in each server
Dual-ported SAS hard drives in the external SAS storage enclosures
Redundant power supplies and fans in the BladeSystem c-Class enclosures and external SAS
storage enclosures.
Using redundant components ensures high availability. If any component in the path between the
server and the storage fails, management software will automatically fail over all I/O to the alternate
path.
Although single-controller shared SAS external storage enclosures are supported for use in
single-domain environments, the dual-controller models are required in high availability environments.
With two controllers, high availability is ensured if one of the controllers fails. During a failover
event, all processing is performed by the remaining controller, with no interruption to the flow of
data.
When configuring the storage, the storage enclosures offer a variety of RAID levels, allowing a
user-selected level of performance and fault tolerance. For more information about RAID levels and
configuring the P2000 G3 SAS MSA Array storage, see the HP MSA2000 G1, MSA 2000 G2,
and P2000 G3 MSA Best Practices white paper at
Library).
Although beyond the scope of this document, clustering is supported in BladeSystem environments,
providing another level of fault tolerance. For more information about clustering support for the
P2000 G3 SAS MSA Array, see the QuickSpecs on the P2000 G3 MSA Array website:
www.hp.com/go/msa.
36 High availability / dual domain information
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