User`s manual

C-11
Appendix C SAS-836EL Backplane Specications
C-13 Failover with RAID Cards and Multiple HBAs
The SAS-836EL backplane may be congured for failover with multiple HBAs using
either RAID controllers or HBAs to acheive failover protection.
RAID Controllers: If RAID controllers are used, then the failover is accomplished
through port failover on the same RAID card.
HBAs: If multiple HBAs are used to achieve failover protection and load balancing,
Linux MPIO software must be installed and correctly congured to perform
the load balancing and failover tasks.
PRI_J0
PRI_J1
PRI_J2
SEC_J0 SEC_J1
SEC_J2
SAS HBA
Port A
Expander 1
Port B
Expander 2
SAS HBA
Dual Host Bus Adapter
In a dual host bus conguration, the
backplane connects to two HBAs.
Figure C-11: Dual HBA
PRI_J0
PRI_J1
PRI_J2
SEC_J0 SEC_J1
SEC_J2
SAS HBA
Port A
Expander 1
Port B
Expander 2
SAS HBA
Dual Host Bus Adapter
Failover
If the expander or data path in Port A
fails, the system automatically switches
to Port B. This maintains a full connec-
tion to all drives.
Figure C-12: Dual HBA Failover
IMPORTANT: For RAID controllers, redundancy is achieved
through port failover. For multiple HBAs, MPIO software is
required to achieve failover protection.
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