The DellTM PowerEdgeTM Expandable RAID Controller (PERC) 4/Di/Si and 4e/Di/Si are embedded subsystems on the motherboard that offer RAID control capabilities. The RAID controller supports all low-voltage differential (LVD) SCSI devices on Ultra320 and Wide SCSI channels with data transfer rates up to 320 MB/sec. PERC 4/Si and 4e/Si support a single channel, while PERC 4/Di and 4e/Di support two channels.
The RAID controller provides reliability, high performance, and fault-tolerant disk subsystem management. It is an ideal RAID solution with Dell PowerEdge systems. This RAID controller offers a cost-effective way to implement RAID in a server and provides reliability, high performance, and fault-tolerant disk subsystem management.
Features
The RAID controller features include:
Wide Ultra320 LVD SCSI performance of up to 320 MB/s
Support for 256 MB (DDR2) memory
64-bit/66 MHz peripheral component interconnect (PCI) host interface for PERC 4/Di/Si
PCI Express x8 host interface for PERC 4e/Di/Si
RAID levels 0 (striping), 1 (mirroring), 5 (distributed parity), 10 (combination of striping and mirroring), and 50 (combination of striping and distributed parity)
Advanced array configuration and management utilities
Ability to boot from any array
One electrical bus: a LVD bus.
NOTE: The PERC 4/Di/Si and 4e/Di/Si RAID controllers support hard disk drives only; they do not support
CD-ROMs, tape drives, tape libraries, or scanners.
Hardware Architecture
PERC 4/Di/Si supports a (PCI) host interface, while PERC 4e/Di/Si supports PCI Express x8 host interface. PCI-Express are high-performance I/O bus architectures designed to increase data transfers without slowing down the CPU. PCI-Express goes beyond the PCI specification in that it is intended as a unifying I/O architecture for various systems: desktops, workstations, mobile, server, communications, and embedded devices.
Maximum Cable Length for 320M SCSI
The maximum length of cable that you can use for LVD 320M SCSI is 12 meters (39' 4"), with a maximum number of 15 devices.
Operating System Support
The RAID controller supports the following operating systems:
Microsoft® Windows® 2000: Server, AS
Windows Server 2003: Standard Edition, Enterprise Edition, Small Business Edition
Novell® NetWare®
RedHat® Linux®
NOTE: See Driver Installationfor the latest operating system versions and driver installation procedures
for the operating systems.
RAID and SCSI Modes
RAID mode allows the channel on the controller to support RAID capabilities, while SCSI mode allows the channel to operate as a SCSI channel. Devices attached to the SCSI channel are not controlled by the RAID firmware and function as if attached to a regular SCSI controller. Check your system documentation to determine supported modes of operation.
You can use system setup to select RAID or SCSI mode. During bootup, press <F2> to access system setup. The PERC 4/Si and 4e/Si RAID controllers work with cache memory and a card key to support one channel, which can be in either SCSI or RAID mode.
The PERC 4/Di and 4e/Di RAID controllers work with cache memory and a card key to provide two SCSI channels to support configurations that span internal channels and external enclosure channels. You can use available physical drives to make a logical drive (volume). The drives can be on different channels, internal or external.
NOTE: The maximum number of drives you can use depends on your system configuration.
For PERC 4/Di and 4e/Di, Table 1-1 displays the possible combinations of SCSI and RAID modes for channels 0 and 1 on the controller.
Table 1-1. SCSI and RAID Modes for the PERC 4/Di and 4e/Di RAID Controller
Mode
Channel 0
Channel 1
RAID
RAID
RAID
RAID/SCSI (if supported by your platform)
RAID
SCSI
SCSI
SCSI
SCSI
NOTE: You cannot set Channel 0 as SCSI while Channel 1 is set as RAID.
Use the mixed mode (RAID on channel 0, SCSI on channel 1, known as RAID/SCSI mode), where available, with a RAID channel for hard drives and a legacy SCSI channel for removable devices or pre-existing hard drives, where available. Not all systems support RAID/SCSI mode.
If both channels are in SCSI mode, you can change channel 0 to RAID to create a RAID/SCSI mode. Dell recommends that you leave the SCSI channel that contains the operating system in SCSI mode. However, you cannot leave channel 0 as SCSI and change channel 1 to RAID, because SCSI/RAID mode is not allowed.
NOTICE: You will lose data if the configuration is changed from SCSI to RAID, RAID to SCSI, or
RAID/RAID to RAID/SCSI.
NOTE: SCSI/SCSI is not a RAID configuration and is available only if you disable RAID by selecting SCSI
mode in the system BIOS. (Access the system BIOS by pressing <F2> during bootup). See your systems
User's Guide to learn how to select SCSI and RAID modes in the system BIOS.
Drive Size in RAID and SCSI Modes
The capacity of a hard drive is reported differently when the hard drive is on the SCSI channel of a PERC 4/Di or 4e/Di controller in RAID/SCSI mode and SCSI/SCSI mode.
The size reported by firmware while in SCSI mode is the actual size in megabytes. For example, a hard drive size of 34734 MB is 36,422,000,000 bytes divided by 1048576 (1024 * 1024, the actual number of bytes in 1 MB), which is off by 2 MB.
In RAID mode, the coerced size is rounded down to the nearest 128 MB boundary, then rounded to the nearest 10 MB boundary. Drives in the same capacity class, such as 36 GB, but from different vendors usually do not have the exact same physical size. With drive coercion, the firmware forces all the drives in the same capacity class to the same size. This way, you can replace a larger drive in a class with a smaller drive in the same class.
Changing the Mode on the Embedded RAID Controller from RAID/RAID to RAID/SCSI Mode or from RAID/SCSI to RAID/RAID Mode
The embedded RAID controller on the system supports two modes of operations: RAID/RAID and RAID/SCSI. The RAID/RAID mode allows the system to use both SCSI channels for RAID only operation. The RAID/SCSI mode allows the system to use RAID for the internal SCSI disk drives and reserves one SCSI channel to allow the connection of internal tape or external SCSI devices. Before changing from RAID/RAID to RAID/SCSI (or from RAID/SCSI to RAID/RAID), you must manually clear the RAID configuration to avoid configuration problems.
NOTE: Dell does not support changing from RAID/RAID to RAID/SCSI or from RAID/SCSI to RAID/RAID
with RAID virtual disks already created. If you change mode without clearing the RAID configuration,
then you may experience unexpected behavior on the system or system instability.
The following procedures are required when changing the embedded RAID controller from RAID/RAID to RAID/SCSI mode or from RAID/SCSI to RAID/RAID mode:
NOTICE: These steps will delete all data on the hard drives. Back up all your data before proceeding.
Clearing the controller configuration:
Reboot the system.
When the RAID controller initialization displays, press <Ctrl> <M> to enter the RAID
controller configuration utility.
If your system has add-on RAID controllers in addition to the embedded RAID controller, proceed to step 3. If your system has only the embedded RAID controller, then proceed to step 5.
Select Select Adapter.
Select the embedded RAID controller and press <Enter>.
Select Configure.
Select Clear Configuration.
NOTICE: All your data will be lost after you perform this step. Do not perform this step until you have
backed up all your data.
Select Yes to confirm.
Press any key to return to the menu.
Press <ESC> twice to exit the menu.
When prompted to exit, select Yes to exit the menu.
Reboot the system.
Changing the RAID Mode
Press <F2> to enter the system BIOS configuration.
Select Integrated devices and press <Enter> to enter the Integrated Devices menu.
Move your selection to Channel B under Embedded RAID controller.
To change from RAID/RAID to RAID/SCSI, change this value from RAID to SCSI.
To change from RAID/SCSI to RAID/RAID, change this value from SCSI to RAID
Press <ESC> to exit the Integrated Devices Menu.
Press <ESC> again to exit the BIOS and reboot the system.
During the system boot, the following warning message displays to confirm the mode change:
Warning: Detected mode change from RAID to SCSI (or from SCSI to RAID) on channel B of the embedded RAID subsystem.
Data loss will occur!
Press <Y> to confirm this change.
Press <Y> again to verify the change.
Recreating your RAID configuration:
When the RAID controller initialization displays, press <Ctrl><M> to enter the RAID
controller configuration utility.
Create the RAID volumes required for your desired configuration.
NOTE: Refer to RAID Configuration and Management for more information on how to create RAID
volumes using the RAID controller configuration utility.
