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Configuring PERC 2/SC, 2/DC, and 3/DCL RAID Controllers

  Description of Controllers

  Array Manager Storage Model

  Virtual Disk Configuration

  Virtual Disk Management

  Array Group Commands

  Array Disk Commands

  PERC Subsystem Commands

  General Controller Commands

  General Channel Commands

  Array and Volume Migration

  FlexRAID Virtual Sizing

  Controller Issues

  Naming Convention Differences

This chapter describes how to configure and manage arrays with the following controllers:


Description of Controllers

The PERC 2/SC, PERC 2/DC, and PERC 3/DCL controllers are high-performance intelligent PCI-to-SCSI host adapters with RAID control capabilities. Each channel supports SCSI data transfer rates of up to 80 MB per second per channel on the PERC 2/SC and PERC 2/DC controllers and up to 160 MB per second per channel for the PERC 3/DCL controller. Each SCSI channel supports up to 15 devices.

Supported RAID Levels

The PERC 2/SC, PERC 2/DC, and PERC 3/DCL controllers support the following RAID levels:

The PERC 2/DC controller also supports RAID-50.

Maximum Virtual Disks per Controller

You can create a maximum of 8 virtual disks on one PERC 2/SC or PERC 2/DC controller. On the PERC 3/DCL controller, you can create a maximum of 40 virtual disks.


Array Manager Storage Model

Working with these controllers requires an understanding of the Array Manager storage model, which represents the Array Manager storage objects in an object hierarchy. Each object has a set of attributes and operations associated with it. Attributes describe the properties of the object, and operations allow you to create new objects and modify existing object attributes. See The Array Manager Storage Model section in the Storage Management Concepts chapter for more information about the Array Manager storage model.

Unless otherwise stated, each operation described in this chapter is available on each controller type listed above. Operations that are grayed out in the console are not supported or not available at that time. To view attributes or to perform operations, right-click on a given storage object. A context menu will appear with a list of commands available, including a Properties command.


Virtual Disk Configuration

Array Manager allows you to create virtual disks, which are logical disks that can be created from one or more physical disks (known as array disks). The logical disks can have RAID layouts, which let you to manage your storage more efficiently. Once a virtual disk is created and a rescan is done, the Windows® operating system sees the virtual disk as if it were a physical disk. The topics in this section are:

See also the section in this chapter on array disks, Array Disk Commands.

Creating Virtual Disks

Creating virtual disks is the first step in configuring your system for improved system management, as well as for software RAID layouts. For more information about creating RAID solutions, see Choosing RAID Levels in the Storage Management Concepts chapter.

When you create virtual disks on PERC 2/SC, PERC 2/DC, and PERC 3/DCL controllers, you may want to consider how virtual disks must be deleted. Because of hardware constraints, virtual disks must be deleted in reverse order of their creation. In other words, you must delete the most recently created virtual disk first and continue to delete in reverse order.

To create a virtual disk:
  1. Right-click on an array group and launch the Create Virtual Disk wizard.

  2. Read the welcome screen and click Next to continue. (You can cancel the operation at any time by clicking the Cancel button.)

  3. The Select Creation Mode dialog box appears. Select Express or Custom Mode, and click Next to continue or Back to return to the previous screen.

  4. If Express Mode is selected, the next screen is Select Virtual Disk Type. Select virtual disk type, size, and the cache policies, and click Next to continue or Back to return to the previous screen. The Default Disk Selection dialog box appears next, which displays the disks that are automatically selected by Array Manager. Click Next to continue.

  5. If Custom Mode is selected, the next screen is Select Disks and Virtual Disk Attributes. Select the disks and enter the desired information, and click Next to continue.

  6. The Completing the Create Virtual Disk wizard dialog box appears next. Click Finish to create a virtual disk or Back to return to the previous screen. Array Manager confirms the creation of the virtual disk.

  7. The Rescan Disk Layout checkbox is checked by default, since it is the recommended setting. Rescan Disk Layout allows Microsoft® Windows NT® or Windows 2000 to recognize the new virtual disk. If the box is not checked when you create the virtual disk, you can complete the same operation later by selecting the Rescan command.

Each virtual disk is automatically mapped to a Microsoft Windows NT or Windows 2000 disk. For example, if Virtual disk 0 is mapped to NT/2000 Disk 0, the Array Manager console will display Virtual disk 0 as "Virtual Disk 0 (Disk 0)," and NT/2000 disk 0 as "Disk 0 (Virtual Disk 0)."

If a virtual disk is not mapped to an NT/2000 disk, please reboot the system.

Deleting Virtual Disks

Deleting a virtual disk permanently deletes all information contained on that disk.

Because of PERC 2/SC, PERC 2/DC, and PERC 3/DCL controller hardware constraints, virtual disks must be deleted in the reverse order of their creation. In other words, the last disk that you created must be deleted first.

To delete a virtual disk:

Use this procedure to delete virtual disks on PERC 2/SC, PERC 2/DC, and PERC 3/DCL controllers.

  1. Right-click on the last virtual disk that was created.

  2. Click Delete. A confirmation dialog box appears. Click OK to continue. The virtual disk disappears from the left pane.

  3. If the disk was not the last one created, a message appears that asks you to delete the most recently created virtual disk first.

CAUTION! All data on the virtual disk is lost when the disk is deleted.
  1. Reboot your system. This step is optional but highly recommended. You should reboot your system after deleting a virtual disk and before creating new ones. This ensures that the operating system recognizes the disk configuration correctly.

Reconfiguring Virtual Disks

This section summarizes how you can change the virtual disk configuration by using the following commands:

Note: You can also change the cache policy of a virtual disk by using the command Change Policy, which is described in the next section.

Add Member

Use this function to add array disks to a virtual disk. You can also change the virtual disk's RAID level.

To add array disks to a virtual disk using Add Member:
  1. Right-click on a virtual disk.

  2. Click Add Member. A Virtual Disk Add Member dialog box appears. The available disks are listed in the left pane. You can choose appropriate ones to add by selecting them and using the Add Disk button to move them to the right pane.

  3. Choose the RAID level in the pull-down list Virtual Disk Type.

  4. Click OK to continue or Cancel to cancel the operation.

  5. Add Member shows progress information in the right pane. To view the progress, click on the parent of the virtual disk. The status of the virtual disk will be Reconstructing, and progress information will display until the Add Member operation is finished. At the end of the operation, the Type category shows the changed RAID level, if the RAID level was changed.

Transform Type

Use the Transform Type function to change the RAID level or stripe size of a virtual disk without adding or removing disks. The following is a list of supported RAID level migrations:

To transform the virtual disk type:
  1. Right-click on the virtual disk for which you want to transform the type.

  2. The Virtual Disk Transform Type dialog box appears. Select the RAID Type or Stripe Size from the available choices.

  3. Click OK to continue or Cancel to quit the operation.

  4. A warning dialog appears asking you whether to continue. Click Yes to continue.

  5. Transform Type displays progress information in the right pane. To view the progress, click on the parent of the virtual disk. The status of the virtual disk will be Reconstructing, and progress information will display until the operation is finished. At the end of the operation, the Type category shows the changed RAID level.


Virtual Disk Management

This section describes the following commands that are used to manage virtual disks:

Change Policy

Use this function to change the cache policies of a virtual disk.

To change the cache policy of a virtual disk:
  1. Right-click on a virtual disk.

  2. Click Change Policy to see the Virtual Disk Change Policy dialog box.

  3. From the pull-down menus, choose the desired policies.

The options are to enable or disable the write cache and to enable or disable the read cache.

  1. Click OK to continue or Cancel to quit the operation.

  2. After the operation, you can click Properties to find out whether the policy changes occurred.

Check Consistency

This function checks mirror synchronization and rebuilds parity if necessary. You also use this function if your disk is in a degraded state. Running Check Consistency may be able to restore your disk to Ready status.

To check consistency and restore redundancy:
  1. Right-click on the virtual disk to be checked.

  2. Click Check Consistency.

  3. The Check Consistency operation displays progress information in the right pane. To view the progress, click on the parent of the virtual disk. The status of the virtual disk will be Resynching, and progress information will display until the operation is finished.

Initialize Virtual Disks

Use this procedure on any virtual disk on a PERC 2/SC, PERC 2/DC, or PERC 3/DCL controller system. The virtual disk will be formatted by this operation. Note that you need to initialize before using any virtual disk.

CAUTION! Initializing a virtual disk destroys any data that is on the disk.
To initialize a virtual disk:
  1. Right-click on the virtual disk that you want to initialize.

  2. Click Initialize. In the right pane, the status of the disk will be Initializing until the operation is finished.

Properties

This command brings up a window that shows the properties associated with the virtual disk.


Array Group Commands

This section describes the commands available on the Array Group context menu. These commands are:

Create Virtual Disk

For more information about this command, see the section Creating Virtual Disks in this chapter.

RAID Policy

This command and the concepts associated with it are discussed in detail in the Policy-Based Storage Management chapter.

Reset Configuration

Use Reset Configuration to wipe out all information on the controller, so that you can perform a fresh configuration.

This operation will destroy any existing virtual disks on the controller. A warning is displayed before the operation is performed. You can cancel the execution at this step.

To reset a configuration:
  1. Right-click on an array group and click Reset Configuration.

  2. You will now need to reconfigure your controllers and virtual disks.

CAUTION! Resetting a configuration permanently destroys all data on these virtual disks.

Properties

This command brings up a window with the properties of the array group.


Array Disk Commands

This section describes the following commands for working with array disks:

Format

The Format command does a low-level formatting of the array disk.

To format an array disk:
  1. Right-click on the disk that you want to format.

  2. Click Format. The right pane shows the status of the format. The status appears as Formatting until the operation is finished.

Rebuild

The Rebuild function is enabled only when a disk has failed. You can rebuild only failed disks in redundant arrays (RAID-1, RAID-5, and RAID-10).

To rebuild a failed disk:
  1. Right-click on the failed disk that you want to rebuild.

  2. Click Rebuild. In the right pane, the status of the disk is Rebuilding and a progress bar shows the percentage of completion.

Assign a Global Hotspare

A hot spare is an unused backup disk that is part of the array group. Hot spares remain in standby mode. When an array disk in a virtual disk fails, the assigned hot spare will be activated to replace the failed array disk without interrupting the system or requiring your intervention.

You can change the hot spare disk assignment by unassigning a disk and choosing another disk to assign, as needed.

Note: Hot spares must be assigned and unassigned manually.
To assign a global hot spare:
  1. Right-click on the array disk that you wish to use as a hot spare.

  2. Click Assign Global Hotspare. The Assign Hot Spare dialog box appears.

  3. To confirm the successful completion of the operation, check the properties displayed in the right pane. The status of the array disk must be Ready and type must be Spare Array Disk.

Unassign a Global Hotspare

Use this operation to unassign the hot spare disk.

To unassign a global hotspare:
  1. Right-click on the disk that is assigned as a hot spare.

  2. Click Unassign Global Hotspare.

  3. To confirm the successful completion of the operation, check the properties displayed in the right pane. The status of the array disk must be Ready and type must be Array Disk.

Online Array Disk

You can set to Online only an array disk that is part of a virtual disk that has been set to Offline.

To online an array disk:

  1. Right-click on the disk that you want to set to Online.

  2. Click Online. In the right pane, the status of the disk is changed from Offline to Online.

Offline Array Disk

To offline an array disk:

You can set to Offline only an array disk that is part of a virtual disk that has been set to Online.

  1. Right-click on the disk that you want to set to Offline.

  2. Click Offline. A confirmation dialog box appears.

  3. Click OK to continue. In the right pane, the status of the disk will be changed from Online to Failed.

Prepare to Remove

Use this procedure to prepare for removing an array disk from a PERC 2/SC, PERC 2/DC, or a PERC 3/DCL controller.

Before you remove any physical disk from an enclosure, it is recommended that you perform this operation to prevent data loss.

To prepare to remove an array disk:
  1. Right-click on the disk that you want to remove.

  2. Click Prepare to Remove, then click OK to continue.

  3. When the lights on the disk you have prepared to remove stop blinking, the disk is ready to be physically removed.

The disk will not be listed in the array group.

Properties

Use this command to display the array disk properties.


PERC Subsystem Commands

The PERC subsystem has the following commands on its context menu:

View Report

This command allows you to view a report on the PERC subsystem.

Save

This command allows you to save the controller configuration.

Properties

Use this command to view the properties of the PERC subsystem.


General Controller Commands

This section describes the following general controller operations:

Rescan Controller

This operation can be used to check whether there are any new disks that were attached after a configuration was set.

  1. Right-click on the controller you want to rescan.

  2. Click Rescan Controller. After the operation is finished, the console is refreshed and the newly attached disks (if there are any) will appear under the Array Disk Group object and under the controller object.

Note: The removal of an array disk within a virtual disk is reflected immediately in the console, whereas an addition is reflected only by performing the Rescan operation. Array disks that are not part of virtual disks will not be polled for status changes.

Flush Cache

The Flush Cache option forces the PERC 2/SC, PERC 2/DC, or PERC 3/DCL controller to write the contents of cache memory onto the virtual disks. You may want to use this option if you find your application or disks in an unstable condition.

Enable Sound

Use this function to enable the controller alarm setting. When enabled, the alarm sounds in the event of a device failure.

To enable sound:

  1. Right-click on a controller.

  2. Click Enable Sound.

Disable Sound

Use this function to disable the alarm. If disabled, the alarm does not sound in the event of a device failure.

To disable sound:

  1. Right-click on a controller.

  2. Click Disable Sound.

Rebuild Rate

Use this command to change the rebuild rate settings.

Properties

This command displays controller attributes.

To view properties:

  1. Right-click on the appropriate controller.

  2. Click Properties. A Controller Properties dialog box appears showing Name, Vendor, Status, Type, Firmware Version, and Cache Size of the controller.


General Channel Commands

This section describes the following general SCSI channel commands:

Rescan Channel

This operation can be used to check whether there are any new disks that were attached to the SCSI channel after a configuration was set.

To rescan a channel:
  1. Right-click on the channel you want to rescan.

  2. Click Rescan. After the operation is finished, the console is refreshed and the newly attached disks (if there are any) appear under the Array Disk Group object and under the channel object.

Note: The removal of an array disk within a virtual disk is reflected immediately in the console, whereas an addition is reflected only by performing the Rescan operation. Array disks that are not part of virtual disks will not be polled for status changes.

Properties

This command displays channel attributes.

To view channel properties:
  1. Right-click on the channel for which you want to view the properties.

  2. Click Properties. A Channel Properties dialog box appears showing Name, Vendor, Status, Type, and Channel Termination.


Array and Volume Migration

This section describes array and volume migration for the PERC 2/SC, PERC 2/DC, and PERC 3/DCL controllers.

Required Conditions

After some planning and preparation, it is possible to migrate array disks, virtual disks and array volumes between one controller and another, between one enclosure and another, or between one server and another. You can perform array and volume migration on PERC 2/SC, PERC 2/DC, and PERC 3/DCL controllers as long as the following conditions are met:

  1. PERC 3/DCL virtual disks cannot be migrated to a PERC 2/SC or PERC 2/DC controller. PERC 2/SC and PERC 2/DC virtual disks can be migrated to a PERC 3/DCL controller.

  2. When moving the array disks from one enclosure to another, the SCSI IDs for each disk must remain the same.

  3. When moving the arrays disks from one enclosure to another or when moving an external enclosure from one server to another, the enclosure must be connected to the same channel number on the controller as in the original condition.

In the case where a virtual disk consists of array disks on multiple channels, each array disk must be migrated to an enclosure that is connected to the same channel number that the array disk or enclosure was originally connected to. This also prevents migration of disks on channel 1 of a PERC 2/DC controller to a PERC 2/SC controller because the PERC 2/SC has only the single channel 0.

  1. A virtual disk cannot be migrated between the PERC 2, PERC 2/Si, PERC 3/Si, and PERC 3/Di controller family and the PERC 2/SC, PERC 2/DC, and PERC 3/DCL controller family.

  2. A virtual disk cannot be migrated from one controller to another unless the receiving controller's configuration has been cleared.

  3. Virtual disks from one controller cannot be merged with virtual disks from another controller.

Steps for Migrating Virtual Disks and Volumes to Another System

To migrate virtual disks and volumes from one system to another, do the following:

  1. Shut down the system that the array disks are being moved from.

  2. If the receiving controller has a preexisting virtual disk configuration on attached array disks, use the following procedure for clearing the configuration:

  3. If the receiving controller does not have a preexisting virtual disk configuration, then shut down its server.

  4. Place the array disks into the new enclosure.

  5. Start up the system connected to the receiving controller. When the system connected to the new enclosure comes up, use the BIOS access (Ctrl-M) to update the controller configuration with the information saved on the array disks. Exiting the BIOS access will require one more reboot of the system.

The migration is complete. The virtual disk is now manageable through Array Manager.

Saving the New Controller Configuration

Use the following procedure to enter the controller BIOS configuration screens to save the new configuration:

  1. Reboot the PowerEdge server.

  2. Enter the PowerEdge RAID Controller BIOS by pressing Ctrl+M when prompted during the power on self test (POST) of the controller during the bootup sequence.

  3. Select the Configure menu option and press Enter.

  4. Select View/Add Configuration and press Enter.

  5. Two choices will appear; choose Disk configuration.

This will read the data on the array disks to restore the RAID controller's proprietary configuration information. Press Esc and save the new configuration when prompted.

  1. Reboot the system.


FlexRAID Virtual Sizing

FlexRAID virtual sizing is a feature of PERC 2/SC and PERC 2/DC controllers. When enabled, the operating system sees your virtual disk as an arbitrarily large disk, typically 1024 GB, instead of its actual size. This lets you add and remove array disks of different sizes to your configuration without having to reboot the system.

Note: This feature is not recommended for use on a Windows 2000 server. It can be used on a Windows NT 4.0 server.

This section on FlexRAID virtual sizing has the following topics:

Enabling FlexRAID Virtual Sizing

This feature is specific to each virtual disk. You create the virtual disk first in Array Manager. Then you must exit Array Manager, reboot the system to bring up the PERC 2/SC or PERC 2/DC controller BIOS utility, and then enable virtual sizing on that virtual disk through a command in the utility.

To enable FlexRAID virtual sizing:
  1. After booting the system, when you see "PowerEdge Expandable RAID Controller...", press Ctrl+M to enter the BIOS configuration utility.

  2. Select Objects.

  3. Select Logical Drives.

  4. Select any logical drive, such as Logical Drive 0. Logical drives and virtual disks are the same.

  5. Select View/Update Parameters.

  6. Go to FlexRAID Virtual Sizing = ... and select Enabled.

  7. Exit the BIOS configuration utility and reboot.

FlexRAID Virtual Sizing Enabled and Disabled

To understand the differences between having FlexRAID virtual sizing enabled and disabled, do the following:

  1. On a Windows NT 4.0 operating system, create a 4-GB virtual disk.

  2. Perform an Add Member operation to increase the size of the virtual disk to 8 GB.

You will see the following differences:

Retained FlexRAID Virtual Sizing Characteristics

In Array Manager, if you delete a virtual disk with FlexRAID virtual sizing enabled and then create another virtual disk in its place, that disk will retain the deleted disk's FlexRAID virtual sizing characteristics. For example, if you just deleted six virtual disks with virtual sizing enabled on them and create eight new ones, you should still see virtual sizing on the first six of them, but not on the last two. To avoid having retained virtual sizing characteristics from deleted virtual disks, reboot before creating new virtual disks.

FlexRAID and Dynamic Volumes

FlexRAID virtual sizing does not work with dynamic volumes. On Windows NT, after upgrading a basic disk that has FlexRAID virtual sizing enabled to a dynamic disk, it will display the actual size of the disk. After reverting this disk back to basic, it will again display the virtual size of 1024 GB. On Windows 2000, you will not be able to upgrade a basic disk to dynamic if FlexRAID virtual sizing is enabled. You do not need FlexRAID virtual sizing on a Windows 2000 machine because you can add storage and create and modify dynamic volumes without having to reboot.


Controller Issues

This section on controller issues covers the following topics:

Array Manager and PERC Console Compatibility Issues

Both Array Manager and PERC Console programs can be installed on the same server. However, only one program can be used to configure PERC 2/SC, PERC 2/DC, and PERC 3/DCL controllers at any given time. To maintain the integrity of storage device configuration, simultaneous use of Array Manager and PERC Console is not supported. It is strongly recommended that Array Manager and PERC Console not be used at the same time on the same server.

Controller Rebuild Rate

During a rebuild, the complete contents of an array disk are reconstructed. A rebuild operation can take place during normal operation, but it will degrade performance.

The rebuild rate is the fraction of the compute cycles dedicated to rebuilding failed array disks. The PERC 2/SC, PERC 2/DC, and PERC 3/DCL rebuild rate can be configured between 0% and 100%. At 0%, the rebuild is done only if the system is not doing anything else. At 100%, the rebuild has a higher priority than any other system activity; the system is totally dedicated to rebuilding the failed array disks.

You can reduce the rebuild rate to maintain system performance during the rebuild operation. However, a reduced rebuild rate extends the rebuild time.

Drive Status Changes

Because of hardware restrictions, the PERC 2/SC, PERC 2/DC, and PERC 3/DCL controllers will not detect a drive status change until I/O is attempted. For example, when an unconfigured drive is removed, the controller will not detect the change until a manual rescan is done or other I/O operations are attempted.


Naming Convention Differences

The terminology used in the Array Manager console differs from the terminology used in the PERC BIOS Configuration Utility. The table below shows a summary of these differences.

Naming convention differences between Array Manager and PERC BIOS Configuration Utility (CU)

Array Manager

PERC BIOS CU

Controller

Adapter

Virtual Disk

Logical Drive

Array Disk

Physical Drive

Add Member/

Transform Type

Reconstruct

Enable Sound

Alarm Control - Enabled

Disable Sound

Alarm Control - Disabled

Write Policy - Cache Disabled

Write Policy - WRTHRU

Write Policy - Cache Enabled

Write Policy - WRBACK

Read Policy - Cache Enabled

Read Policy - ADAPTIVE

Read Policy - Cache Enabled

Read Policy - READAHEAD

Read Policy - Cache Disabled

Read Policy - NO READAHEAD


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