User guide

Compaq StorageWorks RAID Array 4000 User Guide
Consider the following example. The RA4000 controller receives a request for
a physical drive that is not currently active. The controller schedules the
request immediately ahead of previously received requests already queued to
other active drives within the array. This request management process operates
concurrently with drive operations. The benefits of optimized request
management increase as greater demands are made on the drive subsystem.
The RA4000 Controller allows the configuration of one or more separate
logical drives into a single drive array. An existing drive array can be
expanded by adding one or more logical drives to the array. To create the
room for the additional logical drives, more physical drives must be added.
See Figure E-9.
Original
Logical
Drive
Added
Physical
Drives
Figure E-9. Begin capacity expansion by adding more physical drives
When initiated by the Array Configuration Utility, the RA4000 Controller will
automatically redistribute the data in the original logical drive to a logical
drive that spans all of the physical drives in the array, including the added
drives. The room left over is used to create additional logical drives also
spanning all physical drives. All logical drives are then included in the drive
array with expanded storage capacity. See Figure E-10.