IBM Power System Series Manual page 20

v Each SAS adapter can control only three of the disk drives and cannot function in dual-storage I/O
adapter (IOA) mode or in high availability (HA) RAID mode. One SAS adapter (RAID 10 storage
controller) connects to D1, D2, and D3. The other SAS adapter (Base storage controller) connects to D4,
D5, 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 (RAID 0 and
RAID 10). However, RAID drives are limited to three drives and to 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 10 array with one or three drives is not allowed.
v Solid-state drives (SSDs) and hard disk drives (HDDs) can be used.
v SSDs and HDDs can both be present in a split backplane if each side of the split backplane has only
SSDs or HDDs. The supported configurations are as follows:
– SSD on D1 - D3, and HDD on D4 - D6
– HDD on D1 - D3, and SSD on D4 - D6
– SSD on D1 - D6
– HDD on D1 - D6
Example: Two-way split drive backplane
Figure 5 shows a two-way split drive backplane configuration on the 8202-E4C, 8202-E4D, 8205-E6C, or
8205-E6D systems. The pluggable SAS adapter controls three disk drives and the base backplane storage
controller controls three drives in addition to DVD and optional tape storage.
Table 6 on page 9 lists the details of the two-way split drive backplane configuration on the 8202-E4C,
Figure 5. Embedded SAS adapter in a two-way split drive backplane
8202-E4D, 8205-E6C, or 8205-E6D systems.
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SAS subsystem