Service Considerations For The 175 Mb Cache Raid - Dual Ioa Enablement Card - IBM 8412-EAD Manual

Figure 8. Disk bays controlled by each embedded SAS adapter in a two-way split backplane
Review the SAS subsystem configuration that uses a three-way split backplane example. If you add the
optional internal SAS cable for a three-way split backplane (FC 1815), the disk bay configuration changes.
The six disk bays are split into three groups of two. Each of the two embedded SAS adapters controls
two disk bays and a third external PCIe SAS storage adapter controls the remaining two bays. In the
following figure, the highlighted disk bays represent the disk bays that are controlled by each of the
embedded storage adapters (D1, D4, and D2, D5) and the third external PCIe adapter (D3, D6). Each of
the SAS storage adapters now controls different disk bays than in the previous configuration without the
internal SAS cable feature.
Figure 9. Disk bays controlled by adapters in a three-way split backplane
Attention: You must do proper planning and follow proper procedures before adding or removing the
internal SAS cable for a three-way split backplane (FC 1815) to maintain system availability and to
prevent possible data loss.
Related information:
Installing the external SAS port on a 8412-EAD, 9117-MMB, 9117-MMC, 9117-MMD, 9179-MHB,
9179-MHC, or 9179-MHD
Service considerations for the 175 MB cache RAID - dual IOA
enablement card
To prevent data loss, follow proper procedures before replacing the 175 MB cache RAID – dual IOA
enablement card.
Attention: To maintain system availability and to prevent possible data loss, it is important to
understand that these features have implications on the SAS configuration and data accessibility of the
system.
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SAS subsystem