The PERC 2/SC, 2/DC, 3/DCL, 3/DC, and 3/QC 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 3/DCL, 3/DC, and 3/QC controllers. Each SCSI channel supports up to 15 devices. For more information about specific PERC 2/SC, 2/DC, 3/DCL, 3/DC, and 3/QC controllers, refer to the hardware manual that came with the controller.
Note: The PERC 3/DCL, 3/DC, and 3/QC are not supported on
NetWare in this release of Array Manager.
You can create a maximum of 8 virtual disks on one PERC 2/SC or PERC 2/DC controller. On the PERC 3/DCL, 3/DC, and 3/QC controllers, you can create a maximum of 40 virtual disks.
After a failover of cluster resources, it is necessary to perform a rescan operation in order for Array Manager to display the most up-to-date information about shared resources. Array Manager will typically display Unknown or Offline status for resources owned by the other node within a cluster.
It is recommended that shared virtual disks use the entire capacity of the array disks that they are constructed from. This will prevent a situation where a single array disk contains parts of virtual disks that are owned by two different nodes within a cluster.
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.
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:
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, 2/DC, 3/DCL, 3/DC, and 3/QC 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.
Note: With PERC 2/SC, 2/DC, 3/DCL, 3/DC, and 3/QC controllers,
it is recommended that whenever you create a virtual disk, you
use the entire capacity of its member array disks. If you create
a virtual disk that does not use all of the capacity of its member
array disks, then the next virtual disk created must contain the
remaining unused capacity from the previous virtual disk, at a
minimum.
Right-click on an array group and launch the Create Virtual Disk wizard.
Read the welcome screen and click Next to continue. (You can cancel the operation at any time by clicking the Cancel button.)
The Select Creation Mode dialog box appears. Select Express or CustomMode, and click Next to continue or Backto return to the previous screen.
ExpressMode examines your current physical disk layout and available space, and then calculates an appropriate virtual disk layout for you.
CustomMode allows for a more detailed configuration of your choice. You need a good knowledge of RAID levels to use this mode.
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.
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.
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.
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.
Add a write signature to the virtual disk.
When a virtual disk is created with PERC 2/SC, 2/DC, 3/DCL, 3/DC, and 3/QC controllers, a write signature is not automatically written to the disk. Windows NT and Windows 2000 require a write signature on virtual disks. For instructions on writing a disk signature, see the section Write a Disk Signature in the Disk Management chapter. This topic is also covered in the Tutorial chapter in the section Write a Signature.
Use this procedure to delete virtual disks on PERC 2/SC, 2/DC, 3/DCL, 3/DC, and 3/QC controllers.
CAUTION! All data on the virtual disk is lost when the disk is deleted.
Because of PERC 2/SC, 2/DC, 3/DCL, 3/DC, and 3/QC 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.
Right-click on the last virtual disk that was created.
Click Delete. A confirmation dialog box appears. Click OK to continue. The virtual disk disappears from the left pane.
If the disk was not the last one created, a message appears that asks you to delete the most recently created virtual disk first.
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.
Note: If you delete a virtual disk and immediately create a new virtual
disk with all the same characteristics as the one that was deleted, the
controller will recognize the data as if the first virtual disk were never
deleted. In this situation, if you don't want the old data after
recreating a new virtual disk, reinitialize the virtual disk.
Use this function to add array disks to a virtual disk. You can also change the virtual disk's RAID level.
Note: If you add a member to a virtual disk that shares array disk
storage with another virtual disk, you may not be able to create or
delete virtual disks on the controller. Whenever you create a virtual
disk that you plan to expand later with the Add Member command, it is
recommended that you use the entire capacity of its member array
disks.
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 themtothe right pane.
Choose the RAID level in the pull-down list Virtual Disk Type.
Click OK to continue or Cancel to cancel the operation.
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,andprogressinformation 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.
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:
Right-click on the virtual disk for which you want to transform the type.
The Virtual Disk Transform Type dialog box appears. Select the RAID Type or Stripe Size from the available choices.
Click OK to continue or Cancelto quit the operation.
A warning dialog appears asking you whether to continue. Click Yes to continue.
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,andprogressinformation will display until the operation is finished. At the end of the operation, the Type category shows the changed RAID level.
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.
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,andprogressinformation will display until the operation is finished.
Use this procedure on any virtual disk on a PERC 2/SC, 2/DC, 3/DCL, 3/DC, and 3/QC 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.
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.
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.
They are not assigned to specific virtual disks.
Right-click on the array disk that you wish to use as a hot spare.
Click Assign Global Hotspare. The Assign Hot Spare dialog box appears.
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.
Right-click on the disk that is assigned as a hot spare.
Click Unassign Global Hotspare.
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.
Use this command to display the array disk properties.
Note: Array disks for the PERC 2/SC, 2/DC, 3/DCL, 3/DC and
3/QC controllers display Ready status if they are not part of a
virtual disk and Online status if they are part of a virtual disk.
This operation can be used to check whether there are any new disks that were attached after a configuration was set.
Right-click on the controller you want to rescan.
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.
The FlushCache option forces the PERC 2/SC, 2/DC, 3/DCL, 3/DC, and 3/QC controllers 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.
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.
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, 2/DC, 3/DCL, 3/DC, and 3/QC controllers as long as the following conditions are met:
PERC 3/DCL, 3/DC, and 3/QC 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, 3/DC, or 3/QC controller.
When moving the array disks from one enclosure to another, the SCSI ID for each disk must remain the same.
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.
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, 2/DC, 3/DCL, 3/DC, and 3/QC controller family.
A virtual disk cannot be migrated from one controller to another unless the receiving controller's configuration has been cleared.
Virtual disks from one controller cannot be merged with virtual disks from another controller.
To migrate virtual disks and volumes from one system to another, do the following:
Shut down the system that the array disks are being moved from.
If the receiving controller has a preexisting virtual disk configuration on attached array disks, use the following procedure for clearing the configuration:
Shut down the receiving server.
Remove all the array disks from the controller.
Start up the receiving server and clear the configuration from the controller BIOS. After making the changes, power down the server when it indicates to reboot the system.
If the receiving controller does not have a preexisting virtual disk configuration, then shut down its server.
Place the array disks into the new enclosure.
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.
Use the following procedure to enter the controller BIOS configuration screens to save the new configuration:
Reboot the PowerEdge server.
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.
Select the Configure menu option and press Enter.
Select View/Add Configuration and press Enter.
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.
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:
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 understand the differences between having FlexRAID virtual sizing enabled and disabled, do the following:
On a Windows NT 4.0 operating system, create a 4-GB virtual disk.
Perform an Add Member operation to increase the size of the virtual disk to 8 GB.
You will see the following differences:
With FlexRAID virtual sizing disabled, when you try to create a volume, Windows NT indicates that you have a maximum of 4 GB to use for the volume.
With FlexRAID virtual sizing enabled, when you try to create a volume, Windows NT indicates that you have a maximum of 1024 GB to use for the volume. You actually have only 8 GB.
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 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.
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, 2/DC, 3/DCL, 3/DC, and 3/QC 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.
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, 2/DC, 3/DCL, 3/DC, and 3/QC 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.
Because of hardware restrictions, the PERC 2/SC, 2/DC, 3/DCL, 3/DC, and 3/QC 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.
Note: The PERC 2/SC, 2/DC, 3/DCL, 3/DC, and 3/QC controllers
will not report S.M.A.R.T. alerts for unassigned or hot spare
drives.
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)
