IBM 8412-EAD Manual page 21

This configuration increases availability by using dual storage IOA or high availability (HA) to connect
multiple adapters to a common set of internal disk drives. It also increases the performance of RAID
arrays. The following rules apply to this configuration:
v This configuration uses the 175 MB Cache RAID – Dual IOA enablement card.
v Using the dual IOA enablement card, the two embedded adapters can connect to each other and all six
disk drives.
v The disk drives are required to be in RAID arrays.
v No separate SAS cables are required to connect the two embedded SAS RAID adapters to each other.
The connection is contained within the backplane.
v RAID 0, 10, 5, and 6 support up to six drives.
v Solid-state drives (SSDs) and hard disk drives (HDDs) can be used, but they can never be mixed in the
same disk enclosure.
Example: Dual storage IOA using internal drives
This example provides an overview of the dual storage configuration that uses internal disk drives.
Figure 5. Disk bays controlled by both embedded SAS adapters that have dual storage IOA with internal drives
The following table lists the configuration details.
Table 5. Configuration details
Embedded SAS adapters
Two embedded SAS adapters
Configuration details
v RAID mode is required for this configuration.
v The SAS adapters connect to all six disk drives.
v Physical connections to the SAS cable are disabled.
v The two embedded adapters report CCIN 57CF.
9
SAS subsystem