Adaptec 2074700-R User Guide - Page 20

Levels of Drive Hierarchy Within the ICP RAID Firmware

Page 20 highlights

Introduction Figure 1-6. RAID 10 - Combination of RAID 1 and RAID 0 1.3.6 1.3.6.1 1.3.6.2 1.3.6.3 Levels of Drive Hierarchy Within the ICP RAID Firmware The ICP RAID firmware is based on four fundamental levels of hierarchy. Each level has its "own drives" (components). The basic rule is to build up a "drive" on a given level of hierarchy. The "drives" of the next lower level of hierarchy are used as components. Level 1 Physical drives are hard disks and removable hard disks. Some Magneto Optical (MO) drives are located on the lowest level. Physical drives are the basic components of all "drive constructions". However, before they can be used by the firmware, these hard disks must be "prepared" through a procedure called initialization. During this initialization each hard disk receives information which allows an univocal identification even if the SCSI ID or the controller is changed. For reasons of data coherency, this information is extremely important for any drive construction consisting of more than one physical drive. Level 2 On the next higher level are the logical drives. Logical drives are introduced to obtain full independence of the physical coordinates of a physical device. This is necessary to easily change the ICP RAID controller and the channels, IDs, without loosing the data and the information on a specific disk array. Level 3 On this level of hierarchy, the firmware forms the array drives. Depending on the firmware installed an array drive can be: 20 Software Installation and User's Guide

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20
Software Installation and User’s Guide
Introduction
Figure 1-6. RAID 10 - Combination of RAID 1 and RAID 0
1.3.6
Levels of Drive Hierarchy Within the ICP RAID Firmware
The ICP RAID firmware is based on four fundamental levels of hierarchy. Each level has
its “own drives” (components). The basic rule is to build up a “drive” on a given level of
hierarchy. The “drives” of the next lower level of hierarchy are used as components.
1.3.6.1
Level 1
Physical drives
are hard disks and removable hard disks. Some Magneto Optical (MO)
drives are located on the lowest level. Physical drives are the basic components of all
“drive constructions”. However, before they can be used by the firmware, these hard disks
must be “prepared” through a procedure called initialization. During this initialization
each hard disk receives information which allows an univocal identification even if the
SCSI ID or the controller is changed. For reasons of data coherency, this information is
extremely important for any drive construction consisting of more than one physical drive.
1.3.6.2
Level 2
On the next higher level are the
logical drives
. Logical drives are introduced to obtain full
independence of the physical coordinates of a physical device. This is necessary to easily
change the ICP RAID controller and the channels, IDs, without loosing the data and the
information on a specific disk array.
1.3.6.3
Level 3
On this level of hierarchy, the firmware forms the
array drives
. Depending on the
firmware installed an array drive can be: