IBM Power ESE 8412-EAD, Manual

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A three-way split backplane uses three sets of two drives and cannot function in dual storage I/O
adapter (IOA) or high availability (HA) RAID mode. One SAS adapter connects to D1 and D4. The
other SAS adapter connects to D2 and D5. An external SAS adapter connects to D3 and D6.
v
The SAS adapters can be assigned to separate partitions for boot devices.
v
This configuration supports disks without RAID (referred to as JBOD) or RAID drives. However, RAID
drives are limited to two drives and no write cache.
v
RAID 10 with two drives is limited. A RAID 10 array with two drives is equivalent to RAID 1
(mirrored drives). A RAID 0 disk array with one drive is similar to JBOD support. A RAID 10 array
with one drive is not allowed.
v Solid-state drives (SSDs) and hard disk drives (HDDs) can never be mixed in the same disk enclosure.
v
SSD and HDD can both be present in a split backplane if each side of the split backplane has only SSD
or HDD.
Example: Three-way split backplane
This example shows a three-way split backplane configuration. Each embedded SAS adapter controls two
disk drives, and the SAS adapter that is connected to the internal cable controls two disk drives.
Figure 3. Disk bays controlled by each embedded SAS adapter in a three-way split backplane
SAS subsystem
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