IBM Advanced SerialRAID Adapters SA33-3285-02 User Manual page 221

Failure of a Primary Disk Drive in a Dual-Host System: Figure 34 shows a
dual-host system in which the primary disk drive of a RAID-1 array has failed.
Split Array Resolution
= Primary
System 1 System 2
SSA Adapter SSA Adapter
Primary 1 Secondary 1
Figure 34. RAID-1 Disk Drive Failure
Because both adapters can still detect the secondary disk drive of the array, the Split
Array Resolution flag is automatically set to Secondary, and I/O operations continue.
The array is in the Exposed or Degraded state. When the primary disk drive is
reconnected, it is resynchronized from the secondary disk drive, and the Split Array
Resolution flag is automatically set to Primary.
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Chapter 8. Split-Site Management