32 Intel
®
RAID Software User’s Guide
Drive Hierarchy within the RAID Firmware
The Intel
®
Integrated RAID firmware is based on three fundamental levels. Virtual drives are
created from drive arrays that are created from physical drives.
• Level 1 consists of the physical drives (hard drives and removable hard disks). The
firmware identifies each drive by its physical ID and maps it to a virtual address. A
virtual drive can be constructed of more than one physical drive.
• Level 2 consists of the array(s) formed by firmware made of one or more disks and can
be made into RAID 0, 1, 5, 6, 10, 50, or 60.
• Level 3 consists of the virtual drives. These are the only drives that can be accessed by
the operating system. These are the drives given drive letters (C, D, and so forth) under
the Microsoft Windows* operating system. The firmware automatically transforms each
newly installed drive array into a virtual drive. RAID 0, 1, 5, or 6 use a single array and
RAID 10, 50, 60 use multiple arrays.
Intel
®
Intelligent RAID Controller Features
Enterprise Features
• Online capacity expansion (OCE). Add capacity to the virtual drive. The added capacity
can be presented to the operating system as additional space for the operating system to
partition it as an additional drive, or it may be added to an operating system drive,
depending upon the capability of the operating system.
• Online RAID level migration allows for upgrading a RAID level. Options are to go from
RAID 1 to RAID 0, RAID 5 to RAID 0, RAID 6 to RAID 0, RAID 6 to RAID 5. With
OCE, options are to go from RAID 0 to RAID 1, RAID 0 to RAID 5, RAID 0 to RAID 6,
RAID 1 to RAID 5, RAID 1 to RAID 6, RAID 5 to RAID 6.
— You cannot migrate or perform OCE on a spanned RAID array or disk group
(RAID
10, RAID 50, or RAID 60).
— You cannot migrate to a smaller capacity configuration.
— You cannot perform OCE when there is more than one virtual drive on a virtual array
or disk group.
• Each controller allows 128 virtual drives.
• When five or more disks are used, Smart Initialization automatically checks consistency
of virtual drives for RAID 5. This allows performance optimization by enabling read-
modify-write mode of operation with five or more disks in a RAID 5 array or disk group.
Peer read mode of operation is used when the RAID 5 array or disk group contains three
or four physical drives.
• If the system shuts down, the initialization or rebuild process automatically resumes on
the next boot. Auto resume must be enabled prior to virtual drive creation.
• Stripe size is user definable on a per drive basis and can be 8, 16, 32, 64, or 128 KB in
size. The default is 256 KB, which is optimal for many data access types.
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