This chapter describes how to configure and manage arrays with the following 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.
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.
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.
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:
See also the section in this chapter on array disks, Array Disk Commands.
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.
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 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.
Use this procedure to delete virtual disks on PERC 2/SC, PERC 2/DC, and PERC 3/DCL controllers.
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CAUTION! All data on the virtual disk is lost when the disk is deleted. |
This section summarizes how you can change the virtual disk configuration by using the following commands:
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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. |
Use this function to add array disks to a virtual disk. You can also change the virtual disk's RAID level.
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:
This section describes the following commands that are used to manage virtual disks:
Use this function to change the cache policies of a virtual disk.
The options are to enable or disable the write cache and to enable or disable the read cache.
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.
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.
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CAUTION! Initializing a virtual disk destroys any data that is on the disk. |
This command brings up a window that shows the properties associated with the virtual disk.
This section describes the commands available on the Array Group context menu. These commands are:
For more information about this command, see the section Creating Virtual Disks in this chapter.
This command and the concepts associated with it are discussed in detail in the Policy-Based Storage Management chapter.
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.
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CAUTION! Resetting a configuration permanently destroys all data on these virtual disks. |
This command brings up a window with the properties of the array group.
This section describes the following commands for working with array disks:
The Format command does a low-level formatting of the array disk.
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).
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.
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Note: Hot spares must be assigned and unassigned manually. |
Use this operation to unassign the hot spare disk.
You can set to Online only an array disk that is part of a virtual disk that has been set to Offline.
You can set to Offline only an array disk that is part of a virtual disk that has been set to Online.
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.
The disk will not be listed in the array group.
Use this command to display the array disk properties.
The PERC subsystem has the following commands on its context menu:
This command allows you to view a report on the PERC subsystem.
This command allows you to save the controller configuration.
Use this command to view the properties of the PERC subsystem.
This section describes the following general controller operations:
This operation can be used to check whether there are any new disks that were attached after a configuration was set.
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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 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.
Use this function to enable the controller alarm setting. When enabled, the alarm sounds in the event of a device failure.
Use this function to disable the alarm. If disabled, the alarm does not sound in the event of a device failure.
Use this command to change the rebuild rate settings.
This command displays controller attributes.
This section describes the following general SCSI channel commands:
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.
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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. |
This command displays channel attributes.
This section describes array and volume migration for the PERC 2/SC, PERC 2/DC, and PERC 3/DCL controllers.
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:
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.
To migrate virtual disks and volumes from one system to another, do the following:
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:
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.
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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:
You will see the following differences:
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.
This section on controller issues covers the following topics:
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.
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.
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.
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.