Sans Digital Mobileraid MR8X, Detailed User'S Manual

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SAS-to-SATA II RAID Subsystem
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Installation and Configuration Manual
1.5.3 Easy to Use Features
1.5.3.1 Instant Availability/Background Initialization
RAID 0 and RAID 1 Volume Set can be used immediately after the creation. But the RAID 3,
5 and 6 Volume Sets must be initialized to generate the parity. In the Background Mode
initialization, the initialization proceeds as a background task, the Volume Set is fully
accessible for system reads and writes. The operating system can instantly access to the
newly created Volume Sets without waiting for the initialization to be completed. One
disadvantage of this is that the initialization process takes longer time. In Foreground Mode
initialization, the initialization process is faster but must be completed first before the
Volume Set is ready for system access.
1.5.3.2 Array Roaming
The RAID subsystem stores configuration information both in NVRAM and on the disk drives.
This protects the configuration settings in the case of a disk drive or controller failure. Array
roaming allows the administrator the ability to move a complete Raid Set to another system
without losing RAID configuration and data on that Raid Set. If a RAID enclosure fails to
work, the Raid Set disk drives can be moved to another enclosure and inserted in any order.
1.5.3.3 Online Capacity Expansion
Online Capacity Expansion makes it possible to add one or more physical drives to a Raid
Set, while the server is in operation, eliminating the need to backup and restore after
reconfiguring the Raid Set. When disks are added to a Raid Set, unused capacity is added at
the end of the Raid Set. Data on the existing Volume Sets residing on that Raid Set is
redistributed evenly across all the disks. A contiguous block of unused capacity is made
available on the Raid Set. The unused capacity can be used to create additional Volume Set.
The expansion process is illustrated as follows.