Specifications

Chapter 2. Architecture and technical overview 55
Draft Document for Review May 12, 2014 12:46 pm 5102ch02.fm
Figure 2-20 shows the details of the internal topology overview for the #EJ0U DASD
backplane with optional #EJTL 1.8-inch SSD Cage.
Figure 2-20 Internal topology overview for the #EJ0U DASD backplane
The external SAS ports provided by the #EJ0U support the attachment of a single EXP24S
SFF Gen2-bay Drawer (#5887). Additional disk drawers can be attached by using supported
PCIe SAS adapters.
2.6.1 RAID support
There are multiple protection options for HDD/SSD drives in the Power S822 systems,
whether they are contained in the SAS SFF bays in the system unit or drives in disk-only I/O
drawers. Although protecting drives is always recommended, AIX/Linux users can choose to
leave a few or all drives unprotected at their own risk, and IBM supports these configurations.
Drive protection
HDD/SSD drive protection can be provided by the AIX, and Linux operating system, or by the
HDD/SSD hardware controllers.
The default storage backplane #EJ0T contains one SAS HDD/SSD controller and provides
support for JBOD and RAID 0, 5, 6, and 10 for AIX or Linux. A secondary non-redundant
controller is added when using split backplane feature #EJ0V so each six disks have a
separated disk controller.
This controller is replaced when choosing the optional #EJ0U storage backplane by a pair of
High Performance RAID controllers with dual integrated SAS controllers with 1.8 GB of
physical write cache. High performance controllers run SFF-3 SAS bays, 1.8-inch SSD cage
bays, and DVD bay in the system unit. Dual controllers (also called dual I/O adapters or
paired controllers) and their write cache are placed in integrated slots and do not use PCIe