PassThru (Legacy) SCSI Channel on PERC 4/DiDell™ PowerEdge™ Expandable RAID Controller 4/Di User's Guide
PassThru (Legacy) SCSI Channel on PERC 4/Di
This section describes the features of the RAID controller, such as the configuration features, array performance features, hardware specifications, RAID management utilities, and operating system software drivers.
The PERC 4/Di recognizes and uses drive arrays created on existing PERC RAID controllers from the same vendor without risking data loss, corruption, redundancy or configuration loss. Similarly, the arrays created on the PERC 4/Di can be transferred to PERC 4 and newer controllers.
The PERC 4/Di self-monitoring analysis and reporting technology (SMART) detects predictable drive failures. SMART monitors the internal performance of all motors, heads, and drive electronics.
Configuration on disk stores configuration data so that it is always available in case of controller failure. If you have to install a new motherboard because of the failure, you can use the stored data to recover the configuration. Table 2-1 lists the features for configuration on disk.
| Specification |
Feature |
|---|---|
Online RAID level migration | Yes |
No reboot necessary after expansion | Yes |
More than 200 Qtags per array | Yes |
User-specified rebuild rate | Yes |
PERC 4/Di provides the ability to use a passthru (legacy) SCSI channel. This is also known as "RAID/SCSI mode". Use this option for one RAID channel for hard drives, and a legacy SCSI channel for removable devices or pre-existing hard drives. You can select this option in system setup interface.
Devices attached to the SCSI channel are not controlled by the RAID firmware and appear to work as if they are attached to a regular SCSI controller.
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NOTE: The passthru SCSI channel is available only on certain platforms. See your system documentation for more information. |
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NOTE: For information about driver installation, and migration from SCSI mode to RAID mode, refer to the PERC 4/Di Operating System Driver Installation Guide. |
The devices and capabilities supported under the SCSI channel are:
Table 2-2 lists the array performance features.
Table 2-3 lists the features that provide fault tolerance to prevent data loss in case of a failed drive.
|
Specification |
Feature |
|---|---|
Support for SMART | Yes |
Drive failure detection | Automatic |
Drive rebuild using hot spares | Automatic |
Parity generation and checking | Yes |
Table 2-4 lists the utilities and features used to manage arrays and logical drives.
Table 2-5 lists the PERC 4/Di specifications.
Table 2-5. PERC 4/Di Specifications
PERC 4/Di controls hard drives using 320M SCSI buses (channels) over which the system transfers data in either LVD or 320M SCSI modes. Each controller controls two SCSI channels. The SCSI channel supports up to 15 wide or seven non-wide SCSI devices at speeds up to 320 MB/s.
PERC 4/Di uses active termination on the SCSI bus conforming to SCSI-2 and SCSI-3 specifications. Termination enable/disable is automatic through cable detection.
The PERC 4/Di firmware handles all RAID and SCSI command processing and supports the features described in Table 2-6 .
RAID management is provided by software utilities that manage and configure the RAID system and PERC 4/Di, create and manage multiple disk arrays, control and monitor multiple RAID servers, provide error statistics logging, and provide online maintenance. They include:
The PERC 4/Di fault-tolerance features are:
The firmware automatically detects and rebuilds failed drives. This can be done transparently with hot spares.
The RAID controller supports the manual replacement of a disk unit in the RAID subsystem without system shutdown.
Please read all restrictions and disclaimers.