Configuring the raid controller, Configuring scsi physical drives, Physical device layout – Dell PERC 4/DC User Manual
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Configuring the RAID Controller
Dell™ PowerEdge™ Expandable RAID Controller 4/SC and 4/DC User's Guide
Configuring SCSI Physical Drives
This section describes how to configure for physical drives, arrays, and logical drives. It contains tables you can complete to list the configuration for the
physical drives and logical drives.
Configuring SCSI Physical Drives
Your SCSI hard drives must be organized into logical drives in an array and must be able to support the RAID level that you select.
Observe the following guidelines when connecting and configuring SCSI devices in a RAID array:
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You can place up to 32 physical drives in an array.
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When implementing RAID 1 or RAID 5, disk space is spanned to create the stripes and mirrors. The span size can vary to accommodate the different
disk sizes. There is, however, the possibility that a portion of the largest disk in the array will be unusable, resulting in wasted disk space. For example,
consider an array that has the following disks:
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Disk A = 40 GB
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Disk B = 40 GB
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Disk C = 60 GB
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Disk D = 80 GB
In this example, data is spanned across all four disks until Disk A and Disk B and 40 GB on each of Disk C and D are completely full. Data is then spanned
across Disks C and D until Disk C is full. This leaves 20 GB of disk space remaining on Disk D. Data cannot be written to this disk space, as there is no
corresponding disk space available in the array to create redundant data.
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For RAID levels 10 and 50, the additional space in larger arrays can store data, so you can use arrays of different sizes.
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When replacing a failed hard drive, make sure that the replacement drive has a capacity that is the same size or larger than the smallest drive in a
logical drive that supports redundancy (RAID 1, 5, 10, and 50).
Physical Device Layout
to list the details for each physical device on the channels.
Table 4-1. Physical Device Layout
Channel 0
Channel 1
Target ID
Device type
Logical drive number/ drive number
Manufacturer/model number
Firmware level
Target ID
Device type