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SAS subsystem overview

This overview of the SAS subsystem provides the features and locations for the 8412-EAD, 9117-MMB, 9117-MMC, 9117-MMD, 9179-MHB, 9179-MHC, or 9179-MHD system.

Use this information in conjunction with your specific system unit and operating system documentation. General information is intended for all users of this product. Service information is intended for a service representative specifically trained on the system unit and subsystem being serviced.

Feature locations

Review the supported SAS features and their system locations.
Figure 1. SAS subsystem overview
SAS subsystem overview
Table 1. SAS subsystem parts
Diagram location Part name Feature code (FC) Customer card identification numbers (CCINs) Physical location codes
A 175 MB Cache RAID – Dual IOA enablement card 5662

Card CCIN 2BC2

Note: If FC 5662 is installed, the embedded SAS adapters report CCIN 57CF and operate as dual RAID adapters with write cache capability.
 P2-C9-C1
B Cache battery packs     P2-C9-C1-E1 and P2-C9-C1-E2
C Disk bays (6 SFF drive disk bays)     P2-C9-C1-D1 through P2-C9-C1-D6
D Main SAS subsystem card with two embedded SAS adapters  

Card CCIN 2BBE

Notes:
  • If FC 5662 is not installed, the embedded SAS adapters report CCIN 57C7 and operate as two independent adapters.
  • If FC 5662 is installed, the embedded SAS adapters report CCIN 57CF and operate as dual RAID adapters with write cache capability.
 P2-C9
E Optional internal SAS cables:
  • Three-way split disk or media backplane configuration (cable FC 1815)
  • RAID configuration with external drives connected (cable FC 1819)
 1815 or 1819
Notes:
  • 1815 when FC 5662 is not installed 1
  • 1819 when FC 5662 is installed 1
   P2-T2
  Optional rack-mounted media drawer with SAS tape and DVD bays2 5720
Notes:
  • Uses SAS PCIX 2.0 Controller (FC 5900 or 5912) with I/O drawer (FC 5797, 5798, or 5791)
  • Uses SAS Dual-x4 Controller (FC 5901) with I/O drawer (FC 5803)
  P2-C9-D7
  • 1 For detailed configuration information, see SAS storage configurations.
  • 2 The rack-mounted media drawer with SAS tape and DVD bays is an optional part, and hence is not shown in the figure.
Feature details
SAS RAID adapters
The SAS RAID adapters have the following features:
  • PCI Express (PCIe) system interface
  • Physical link (phy) speed of 3 Gbps SAS supporting transfer rates of 300 MB per second
  • Optimized for SAS disk configurations that use dual paths through dual expanders for redundancy and reliability
  • Adapter managed path redundancy and path switching for multiported SAS devices
  • Embedded PowerPC RISC processor, hardware XOR DMA Engine, and hardware Finite Field Multiplier (FFM) DMA Engine (for Redundant Array of Independent Disks (RAID) 6)
  • Support for RAID 0 and 10 disk arrays
  • Additional features when the 175 MB Cache RAID – Dual IOA enablement card is installed:
    • Adapters support nonvolatile write cache
    • Support for RAID 5 and 6 disk arrays
    • Adapters configured in dual storage IOA or high availability (HA) RAID mode for best reliability and availability
  • RAID disk arrays supported as a boot device
  • Advanced RAID features:
    • Hot spares for RAID 5, 6, and 10 disk arrays
    • Ability to increase the capacity of an existing RAID 5 or 6 disk array by adding disks
    • Background parity checking
    • Background data scrubbing
    • Disks formatted to 528 bytes per sector, providing cyclical redundancy checking (CRC) and logically bad block checking
    • Optimized hardware for RAID 5 and 6 sequential write workloads
    • Optimized skip read/write disk support for transaction workloads
175 MB cache RAID – Dual IOA enablement card
This feature is used to enable write cache on the two embedded SAS RAID adapters of the disk or media backplane by providing the necessary rechargeable batteries for memory backup. It also enables the two embedded SAS RAID adapters to work as dual storage IOAs, that is, high availability (HA) RAID mode. This feature plugs in to the disk or media backplane and enables a 175 MB write cache on each of the two embedded RAID adapters by providing two rechargeable batteries with associated charger circuitry. The write cache can provide additional I/O performance for attached disk or solid-state drives, particularly for RAID 5 and RAID 6. The write cache contents are mirrored for redundancy between the two RAID adapters resulting in an effective write cache size of 175 MB. The batteries provide power to maintain both copies of write-cache information in the event power is lost.
Parent topic: SAS architecture
Related information:
Serial-attached SCSI cable planning
PCIe SAS RAID card comparison

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Last updated: Thu, October 10, 2013