Raid Software Stack; General Raid Features - Intel SE7520AF2 Technical Product Specification

Integrated Intel® RAID Controller SROMBU42E
4.3

RAID Software Stack

The software described in this document is relevant to the integrated Intel® RAID Controller
SROMBU42E functionality of the Intel® Server Board SE7520AF2, and is designated as
Software Stack 2. This section describes the RAID controller, drive and array configuration,
management utility operation, and drive installation. This software stack is not backward
compatible with the previous software stack, Software Stack 1. Software Stack 2 is also not
compatible with controllers designed for use with Software Stack 1, including the Intel® RAID
Controller SRCMR, SRCZCR, SRCU31, SRCU31L, SRCU32, SRCU42L, and SRCS14L. It is
not possible to "Roam" drives between these two software stacks.
4.3.1

General RAID Features

The Intel® SROMBU42E RAID functionality supports online capacity expansion (OCE).
This added capacity can be added to the logical drive and may be presented to the
operating system as additional space for the operating system to partition as an
additional drive, or may be added to an operating system drive, depending upon the
capability of the operating system.
Online RAID level migration allows for the upgrading of a RAID level (for example, RAID
1 to RAID5), but may require online capacity expansion as part of the process.
Note: This functionality cannot migrate or perform OCE on a spanned RAID, or migrate
to a smaller capacity configuration.
Current firmware and utilities do not allow Random Deletion of logical drives. Drives
must be removed in reverse order of creation.
The total capacity of a configured drive array must be used by one or more logical drives
before additional drive arrays can be configured.
Smart Initialization automatically checks consistency of logical drives when five or more
disks are configured in a RAID 5 logical drive. This allows performance optimization by
enabling read modify write mode of operation with five or more disks in a RAID 5 array.
Peer read mode of operation is used when the RAID 5 array contains three or four
physical drives.
The initialization or rebuild process will automatically resume on the next boot if the
system shuts down. Auto resume must be enabled prior to logical drive creation.
Stripe size is user definable on a per drive basis and can be 2, 4, 8, 16, 32, 64, or 128
kb in size. The default is 64 kb, which has been found to be optimal for many data
access types.
Hot spares can be set as global or dedicated. A global hot spare will automatically come
online to replace the first drive to fail on any array on the controller. A dedicated hot
spare is assigned to a specific array and will only come online to rebuild a failed drive in
that array. A hot spare will only come online if it is the same size or larger than the failing
drive (see drive coercion below), and if a drive has been marked as failed. A hot spare
can be used across channels on the same RAID controllers. If a drive is removed (and
marked as failed) within a logical drive, the hot spare will automatically come online.
However, there must be disk activity (I/O to the drive) in order for a missing drive to be
marked as failed.
86
Intel order number C77866-003
Intel® Server Board SE7520AF2 TPS
Revision 1.2