Q-Logic 8200 SERIES User Manual

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2 – General Description
 
Supported Network Configurations
2-6
 
SN0054628-00  A
Q
2.3.3
 
High-Availability Configuration
High availability describes a system that is operational a high percentage of the 
time. Through dual redundancy, a system can maintain high availability in the 
presence of any single component failure. 
Use of redundant components, multipathing, and failover help protect against 
failures and ensure high availability. Implementing SVM agents on SANbox SSP 
provides high availability by allowing the use of multiple paths between servers and 
storage, and ensuring that no single point of failure can prevent access to data.
Failover is a backup operational mode in which the functions of a system component 
(such as, a server, network, or storage controller, for example) are assumed by 
secondary system components when the primary component becomes unavailable 
through either failure or scheduled down time.
With the proper multipathing software running on the host, a high-availability 
configuration can guarantee access to data even in the event of one or possibly 
more hardware, software, or infrastructure failures. With the addition of multiple 
hosts running supported clustering software, even host failures can be tolerated 
without interrupting critical applications.
In addition to continuous operation through unplanned failures, a correctly set up 
high-availability configuration enables administrators to take components of the 
system offline for maintenance or replacement, again without interrupting access 
to data. 
 shows a recommended high-availability configuration with 
cross-connected fabric. Within each fabric, zoning is used to partition the front-side 
initiator ports, both StoreAge SVM ports, and back-side storage. Each server has 
multiple HBAs installed, with at least one HBA connected to each of two redundant 
front-side fabrics. Each HBA sees the same virtual disks on each of two redundant 
SANbox SSPs. Each SANbox SSP has access to physical storage through at least 
two paths, across two fabrics and at least two RAID controllers. Two SVMs can 
each manage either or both SANbox SSP units. Two independent fabrics and host 
failover software ensure availability.