Technical information

IBM Europe, Middle East, and Africa Hardware
Announcement ZG14-0098
IBM is a registered trademark of International Business Machines Corporation
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The dual SAS controllers provide both performance and protection advantages.
Patented Active-Active capabilities enhance performance when there is more than
one array configured. Each of the dual controllers has access to all the backplane
SAS bays and can back up the other controller if there were to be a problem with
the other controller. Each controller mirrors the other's write cache, providing
redundancy protection. Integrated flash memory for the write cache content
provides protection against electrical power loss to the server and avoids the need
for write cache battery protection and battery maintenance.
All three of these backplane options support HDDs or SSDs or a mixture of HDDs
and SSDs in the SFF-3 bays. If mixing HDDs and SSDs, they must be in separate
arrays (unless using Easy Tier function).
All three of these backplane options can offer different drive protection options:
RAID 0, RAID 5, RAID 6, or RAID 10. RAID 5 requires a minimum of three drives of
the same capacity. RAID 6 requires a minimum of four drives of the same capacity.
RAID 10 requires a minimum of two drives. Hot spare capability is supported with
RAID 5 or RAID 6. The high-performance, expanded-function dual-IOA backplane
also proves Easy Tier functionality, which is also called RAID 5T2 (2-tiered RAID 5),
RAID 6T2 (2-tiered RAID 6), and RAID 10T2 (2-tiered RAID 10).
Note: I/O performance-sensitive workloads with an appreciable percentage
of writes should strongly consider using the feature EJ0P backplane with SAS
controllers with write cache or use PCIe SAS controllers with write cache, especially
for HDD. Note also that RAID 5 and RAID 6 result in more drive write activity than
mirroring or than unprotected drives.
All three of these backplane options are supported by AIX, IBM i, Linux, and VIOS.
If used by IBM i, to be a supported configuration, the drives must be protected by
methods such as RAID 5, RAID 6, or mirroring. If used by AIX, Linux, or VIOS, it is
highly recommended that the drives be protected, but not required.
If the client needs a change after the server is already installed, the backplane
option can be changed. For example, the feature EJ0S split backplane can be added
to an existing feature EJ0N backplane. Or the feature EJ0N can be removed and
replaced by the expanded-function dual IOA feature EJ0P backplane. Or a feature
EJ0P backplane could be replaced by a feature EJ0N and EJ0S backplane.
Unlike the hot plug PCIe slots and SAS bays, concurrent maintenance is not
available for the integrated SAS controllers. Scheduled downtime is required if a
service action is required for these integrated resources.
SSD cage
In addition to supporting HDDs and SSDs in the SFF-3 SAS bays, the expanded-
function feature EJ0P supports a mandatory 8-bay, 1.8-inch SSD Cage (#EJTM).
All eight bays are accessed by both of the integrated SAS controllers. The bays
support concurrent maintenance (hot plug). SSD 1.8-inch drives such as the 387 GB
capacity feature ES16 or ES17 are supported.
DVD drive bay
Included in the feature EJ0N or EJ0P backplanes is a slimline media bay that can
optionally house a SATA DVD-RAM (#5771). The DVD drive is run by the integrated
SAS controllers, and a separate PCIe controller is not required.
Storage Backplane Integrated Easy Tier function
The Easy Tier function is provided with the dual IOA, high-performance storage
backplane (#EJ0P). Conceptually, this function is like the Easy Tier function
found in the IBM Storage products such as the DS8000®, Storwize® V7000, or
SVC, but implemented just within the integrated Power Systems SAS controllers,
the integrated SAS bays, and, optionally, an EXP24S I/O drawer. Hot data is
automatically moved to SSDs, and cold data is automatically moved to disk (HDD) in
an AIX, Linux, or VIOS environment. No user application coding is required.