PERC Configuration Manager is a character-based, non-GUI utility that configures and monitors RAID systems. PERC Configuration Manager runs under Novell NetWare 4.11.

The topics discussed in this chapter include:

• starting PERC Configuration Manager,
• PERC Configuration Manager menus,
• choosing a configuration method,
• designating drives as hot spares,
• creating physical arrays,
• defining logical drives,
• initializing logical drives,
• using logical drives in your operating system, and
• rebuilding failed disk drives.

To start PERC Configuration Manager, make sure the program file is in your file path. Type the command:

The first PERC Configuration Manager screen is:

The PERC Configuration Manager options are:

For information about other functions, see the following menu tree and menu descriptions.

Figure 1. PERC Configuration Manager Menu Tree

These menu items are described on the following pages.

Choose the Configure option to select a method for configuring arrays and logical drives.

Choose this option from the PERC Configuration Manager main menu to initialize one or more logical drives. This action typically follows the configuration of a new logical drive.

Choose the Objects option from the PERC Configuration Manager main menu to access the controllers, logical drives, physical drives, and SCSI channels individually. You can also change certain settings for each object. The Objects menu options are described below.

Choose the Adapter option from the Objects menu to select a PERC controller if your computer has more than one and to modify parameters. You can install only one PERC 2/DC controller, but you can install other PERC controllers in the computer.

Choose this option from the Objects menu to select a logical drive and to perform the listed actions.

Choose this option from the Objects menu to select a physical device and perform the operations listed below. When you choose this option, the physical drives in the computer are listed. Move the cursor to the desired device and press <Enter>. The following appears:

Choose this option from the Objects menu to select a SCSI channel on the currently selected controller. You can perform the following operations on the selected channel.

Choose this option from the Options menu to view the battery backup information, as shown below. You can use the battery backup menu to reset the charge cycle count.

Table 9. Battery Backup Menu Items

Choose the Format option from the PERC Configuration Manager main menu to low-level format one or more physical drives.

Since most SCSI disk drives are low-level formatted at the factory, this step is usually not necessary. You typically must format a disk if:

• the disk drive was not low-level formatted at the factory, or
• an excessive number of media errors have been detected on the disk drive.

You do not need to use the Format option if you simply want to erase existing information on your SCSI disks, such as a DOS partition. That information is erased when you initialize the logical drive(s).

Choose the Rebuild option from the PERC Configuration Manager main menu to rebuild one or more failed disk drives.

Choose this option to verify the redundancy data in logical drives using RAID levels 1 or 5. When you choose Check Consistency, the parameters of the existing logical drives on the current controller appear. The logical drives are listed by number. PERC 2/DC automatically corrects any differences found in the data.

Press the arrow keys to select the desired logical drives. Press the spacebar to select or deselect a drive for consistency checking. Press <F2> to select or deselect all the logical drives.

Press <F10> to begin the consistency check. A progress indicator for each selected logical drive appears, as shown below:

When the consistency check is finished, press any key to clear the progress display and press <Esc> to display the main menu.

You can select or deselect a logical drive to be recreated using this option. Choose this option before you add or remove a physical drive.

You can configure physical arrays and logical drives with PERC Configuration Manager using:

• Auto Configuration,
• Easy Configuration,
• New Configuration, or
• View/Add Configuration

Each configuration method requires a different level of user input. The general flow of operations for array and logical drive configuration is:

If logical drives have already been configured when you select Auto Configuration, the configuration information is not disturbed.

In Easy Configuration, each physical array you create is associated with exactly one logical drive, and you can modify the following parameters:

• RAID level,
• stripe size
• cache write policy,
• Read policy, and
• I/O policy.

If logical drives have already been configured when you select Easy Configuration, the configuration information is not disturbed.

In New Configuration, you can modify the following logical drive parameters:

• RAID level,
• stripe size
• cache write policy,
• Read policy,
• I/O Policy,
• logical drive size, and
• spanning of arrays.

If you select New Configuration, the existing configuration information on the selected controller is destroyed when the new configuration is saved.

View/Add Configuration allows you to control the same logical drive parameters as New Configuration without disturbing the existing configuration information.

Up to 20.6 MB of disk space is reserved when a hard disk drive is being configured.

Hot spares are physical drives that are powered up along with the RAID drives and usually stay in a standby state. If a disk drive used in a RAID logical drive fails, a hot spare will automatically take its place and the data on the failed drive is reconstructed on the hot spare. Hot spares can be used for level 1 and 5 RAID. Each PERC 2/DC controller supports up to eight hot spares. See Chapter 2 Introduction to RAID for an explanation of hot spares.

The two methods for designating physical drives as hot spares are:

• press <F4> while creating arrays in Easy, New or View/Add Configuration mode, or
• highlight a drive using the spacebar, press <Enter>, and select Make HotSpare.

When you choose any configuration option in the Configure menu, all physical devices connected to the current controller appear:

Press the arrow keys to select a disk drive that has a READY indicator and press <F4> to designate it as a hot spare. Choose Yes to confirm. The indicator changes to HOTSP when you do.

Select Objects from the Configure menu, then select Physical Drive. A physical drive selection screen will appear. Press the spacebar to select a disk drive and press <Enter> to display the action menu for the drive.

Press the arrow keys to select Make Hot Spare and press <Enter>. The indicator for the selected drive changes to HOTSP.

In Auto Configuration, PERC 2/DC examines the physical drives connected to it and automatically configures them into arrays and logical drives. PERC 2/DC uses the following configuration guidelines in the following sequence:

The default logical drive settings will be:

The write policy, read policy, and cache policy can be changed after configuration is complete.

Perform the following steps when using auto configuration:

In Easy Configuration, each array is associated with exactly one logical drive. Follow the steps below to create arrays using Easy Configuration:

The New Configuration option allows you to associate logical drives physical arrays (this is known as spanning of arrays).

Choose the New Configuration option to erase the existing configuration information about the selected controller.

To use the spanning feature and keep the existing configuration, use View/Add Configuration.

<F2> Display the manufacturer data and PERC 2/DC error count for the selected drive.

<F3> Display the logical drives that have been configured.

<F4> Designate the selected drive as a hot spare.

<F10> Display the logical drive configuration screen.

3. Press the arrow keys to select specific physical drives. Press the spacebar to associate the selected physical drive with the current array. The indicator for the selected drive changes from READY to ONLIN A[array number]-[drive number]. For example, ONLIN A2-3 means disk drive 3 in array 2.

Add physical drives to the current array as desired. Try to use drives of the same capacity in a specific array. If you use drives with different capacities in an array, all the drives in the array is treated as though they have the capacity of the smallest drive in the array.

The number of physical drives in a specific array determine the RAID levels that can be implemented with the array.

RAID 0 requires one or more physical drives per array.

RAID 1 requires two physical drives per array.

RAID 5 requires at least three physical drives per array.

4. Press <Enter> when you are finished creating the current array. To continue defining arrays, repeat step 3. To begin logical drive configuration, go to step 5.

5. Press <F10> to configure logical drives. The logical drive configuration screen appears:

The window from the top of the screen shows the logical drive that is currently being configured as well as any existing logical drives. The column headings are:

LD - The logical drive number,

RAID - The RAID level,

Size - The logical drive size,

#Stripes - The number of stripes (physical drives) in the associated physical array,

StrpSz - The stripe size, and

Drive-State - The state of the logical drive.

6. Set the RAID level for the logical drive. Highlight RAID and press <Enter>. The available RAID levels for the current logical drive are listed. Select a RAID level and press <Enter> to confirm. See Chapter 3 RAID Levels for an explanation of RAID levels.

7. Set the spanning mode for the current logical drive. Highlight Span and press <Enter>. The choices are:

For two arrays to be spannable, they must have the same stripe width (they must contain the same number of physical drives) and the arrays must be consecutively numbered. For example, assuming Array 2 contains four disk drives, it can be spanned only with Array 1 and/or Array 3, and only if Arrays 1 and 3 also contain four disk drives. If the two criteria for spanning are met, PERC 2/DC allows spanning. If the criteria are not met, the Span setting makes no difference for the current logical drive. Highlight the spanning option and press <Enter>.

8. Set the logical drive size. Move the cursor to Size and press <Enter>. By default, the logical drive size is set to all available space in the array(s) being associated with the current logical drive, accounting for the Span setting and for partially used array space. For example, if the previous logical drive used only a part of the space in an array, the current logical drive size is set to the remaining space by default.

9. Choose the Advanced menu to set remaining options.

Write Policy This parameter specifies the cache write policy. You can set the write policy to write-back or write-through.

In Write-back caching, the controller sends a data transfer completion signal to the host when the controller cache has received all the data in a transaction. This is the default setting.

In Write-through caching, the controller sends a data transfer completion signal to the host when the disk subsystem has received all the data in a transaction.

Write-through caching has a data security advantage over write-back caching. Write-back caching has a performance advantage over write-through caching.

Read-ahead This parameter specifies that the SCSI read-ahead feature is used for the logical drive. You can set this parameter to Normal, Read-ahead, or Adaptive.

Normal specifies that the controller does not use read-ahead for the current logical drive.

Read-ahead specifies that the controller uses read-ahead for the current logical drive.

Adaptive specifies that the controller begins using read-ahead if the two most recent disk accesses occurred in sequential sectors. If all read requests are random, the algorithm reverts to Normal, however, all requests are still evaluated for possible sequential operation. This is the default setting.

Cache Policy This parameter applies to reads on a specific logical drive. It does not affect the Read ahead cache.

Cached I/O specifies that all reads are buffered in cache memory. This is the default setting.

Direct I/O specifies that reads are not buffered in cache memory.

Direct I/O does not override the cache policy settings. Data is transferred to cache and the host concurrently. If the same data block is read again, it comes from cache memory.

Press <Esc> to exit the Advanced Menu.

10. After the current logical drive is defined, select Accept and press <Enter>. If space remains in the arrays, the next logical drive to be configured appears. Repeat steps 6 to 9 to configure another logical drive. If all array space has been used, a list of the existing logical drives appears. Press any key to continue and respond to the Save prompt.

11. Initialize the logical drives you have just configured.

View/Add Configuration allows you to associate logical drives with physical arrays. (This is known as array spanning.)

The existing configuration is left intact, so you can also use View/Add Configuration simply to look at the current configuration.

<F2> Display the manufacturer data and PERC 2/DC error count for the selected drive.

<F3> Display the logical drives that have been configured.

<F4> Designate the selected drive as a hot spare.

<F10> Display the logical drive configuration screen.

3. Press the arrow keys to select the physical drives. Press the spacebar to select physical drives to be associated with the current array. The indicator for the selected drive changes from READY to ONLIN A[array number]-[drive number]. For example, ONLIN A2-3 means disk drive 3 in array 2.

Add physical drives to the current array as desired. Try to use drives of the same capacity in a specific array. If you use drives with different capacities in an array, all drives in the array are treated as if they have the capacity of the smallest drive in the array.

The number of physical drives in a specific array determine the RAID levels that can be implemented with the array.

RAID 0 requires one or more physical drives per array.

RAID 1 requires two physical drives per array.

RAID 5 requires at least three physical drives per array.

4. Press <Enter> to end the selection process. To continue defining arrays, repeat step 3. To begin logical drive configuration, go to step 5.

5. Press <F10> to configure logical drives. The logical drive configuration screen appears:

The window at the top of the screen shows the logical drive that is currently being configured as well as any existing logical drives. The column headings are:

LD - The logical drive number,

RAID - The RAID level,

Size - The logical drive size,

#Stripes - The number of stripes (physical drives) in the associated physical array,

StrpSz - The stripe size, and

Drive-State - The state of the logical drive.

6. Set the RAID level for the logical drive. Highlight RAID and press <Enter>. The available RAID levels for the current logical drive are displayed. Select a RAID level and press <Enter> to confirm. See Chapter 3 RAID Levels for an explanation of the RAID levels.

7. Set the spanning mode for the current logical drive. Highlight Span and press <Enter>. The choices are:

For two arrays to be spannable, they must have the same stripe width (they must contain the same number of physical drives) and must be consecutively numbered. For example, assuming Array 2 contains four disk drives, it can be spanned only with Array 1 and/or Array 3, and only if Arrays 1 and 3 also contain four disk drives. If the two criteria for spanning are not met, the Span setting makes no difference for the current logical drive. Highlight a spanning option and press <Enter>.

8. Set the logical drive size. Move the cursor to Size and press <Enter>. By default, the logical drive size is set to all available space in the array(s) being associated with the current logical drive, accounting for the Span setting and for partially used array space. For example: if the previous logical drive used only a part of the space in an array, the current logical drive size is set to the remaining space by default.

9. Open the Advanced menu to set the remaining options.

A larger stripe size produces better read performance, especially if your computer does mostly sequential reads. However, if you are sure that your computer does random reads more often, select a small stripe size. The default stripe size is 64 KB.

Write Policy This parameter sets the cache write policy. You can set the write policy to write-back or write-through.

You should initialize each new logical drive you configure. You can initialize the logical drives in two ways:

• Batch Initialization The Initialize option in the main menu lets you initialize up to eight logical drives simultaneously.
• Individual Initialization The Objects/Logical Drive action menu for an individual logical drive has an Initialize option.

Batch Initialization

Individual Initialization

You can do low-level formatting of SCSI drives using PERC Configuration Manager.

Since most SCSI disk drives are low-level formatted at the factory, this step is usually not necessary. You typically must format a disk if:

• the disk drive was not low-level formatted at the factory, or
• an excessive number of media errors have been detected on the disk drive.

Check the properties screen for the drive you wish to format. You can check this screen by choosing Objects from the Physical Drive menu, pressing the arrow keys to select the selected drive and pressing <F2>.

The error count appears at the bottom of the properties screen. If you feel that the number of errors is excessive, you should probably format the disk drive. If more than 32 media errors were detected, PERC 2/DC automatically puts the drive in FAIL state. In cases such as this, formatting the drive can clear up the problem.

You do not have to use the Format option to erase existing information on your SCSI disks, such as a DOS partition. That information is erased when you initialize logical drives.

You can format the physical drives using:

• Batch Formatting. The Format option in the PERC Configuration Manager main menu lets you format up to eight disk drives simultaneously.
• Individual Formatting. Choose the Format option from Objects on the Physical Drive action menu for an individual disk drive.

Batch Formatting

If a disk drive fails in an array configured as a RAID 1 or 5 logical drive, you can recover the lost data by rebuilding the drive. If a rebuilding spare fails, a new rebuild is started using a second spare, if available. The capacity of the second spare must be equal to or greater than the failed drive.

Manual Rebuild - Rebuilding an Individual Drive

Manual Rebuild - Batch Mode

To exit PERC Configuration Manager, press <Esc> from the main menu and choose Yes at the prompt. A message appears if uninitialized logical drives remain in the system.