figure 47 raid 00 configuration preview dialog...18. check the information in the configuration...

MegaRAID SAS Software User GuideDecember 2011

Chapter 4: WebBIOS Configuration UtilityCreating a Storage Configuratio

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Figure 47 RAID 00 Configuration Preview Dialog

18. Check the information in the Configuration Preview Dialog.

19. Perform one of these actions:

— If the virtual drive configuration is acceptable, click Accept to save the configuration. — To end the operation and return to the WebBIOS main menu, click Cancel.— To return to the previous dialogs and change the configuration, click Back.

20. If you accept the configuration, click Yes at the prompt to save the configuration.

Another confirmation for initialization appears.


— Click No to view the WebBIOS main menu.— Click Yes, and the initialization process takes place, and the WebBIOS Config Utility Virtual Drive

dialog appears.

4.5.2.6 Using Manual Configuration: RAID 10

RAID 10, a combination of RAID 1 and RAID 0, has mirrored drives. It breaks up data into smaller blocks, then stripes the blocks of data to each RAID 1 drive group. Each RAID 1 drive group then duplicates its data to its other drive. The size of each block is determined by the stripe size parameter, which is 64 KB. RAID 10 can sustain one drive failure in each drive group while maintaining data integrity.

RAID 10 provides both high data transfer rates and complete data redundancy. It works best for data storage that must have 100 percent redundancy of RAID 1 (mirrored drive groups) and that also needs the enhanced I/O performance of RAID 0 (striped drive groups); it works well for medium-sized databases or any environment that requires a higher degree of fault tolerance and moderate to medium capacity.

When you select Manual Configuration and click Next, the Drive Group Definition dialog appears.

You use the Drive Group Definition dialog to select drives to create drive groups.

1. Press and hold the Ctrl key while selecting two unconfigured good drives in the Drives panel on the left.

2. Click Add To Array to move the drives to a proposed two-drive group configuration in the Drive Groups panel on the right.

If you need to undo the changes, select the drive, and click Reclaim.

3. Click Accept DG to create a first drive group.

An icon for the next drive group appears in the right panel.

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Chapter 4: WebBIOS Configuration UtilityCreating a Storage Configuration

4. Press and hold the Ctrl key while selecting the same number of unconfigured good drives in the Drives panel (that were selected for the first drive group) to create a second drive group.

5. Click Add To Array to move the drives to a second drive group configuration in the Drive Groups panel, as shown in Figure 48.


6. Choose whether to use power saving.

7. Choose whether to use drive encryption.

Figure 48 Drive Group Definition Dialog

8. Repeat step 1 through step 5 until you have created all the required drive groups.

9. Click Next.

The Span Definition dialog appears, as shown in Figure 49. This dialog displays the drive group holes you can select to add to a span.

NOTE RAID 10 supports a maximum of eight spans, with a maximum of 32 drives per span. (Other factors, such as the type of controller, can limit the number of drives.) You must use an even number of drives in each RAID 10 drive group in the span.




Figure 49 Span Definition Dialog

10. Under the Array With Free Space column, select a drive group, and click Add to SPAN.

The drive group you select is displayed in the right frame under the heading Span.

11. Select another drive group, and click Add to SPAN.If there are additional drive groups with two drives each, you can add them to the Span.

12. Click Next.

The Virtual Drive Definition dialog appears, as shown in Figure 50. You use this dialog to select the RAID level, strip size, read policy, and other attributes for the new virtual drives.




Figure 50 WebBIOS Virtual Drive Definition Dialog

13. Change the virtual drive options from the defaults listed on the dialog as needed.

Here are brief explanations of the virtual drive options:

— RAID Level: The drop-down menu lists the possible RAID levels for the virtual drive. Select RAID 10.— Strip Size: The strip size is the portion of a stripe that resides on a single drive in the drive group. The stripe

consists of the data segments that the RAID controller writes across multiple drives, not including parity drives. For example, consider a stripe that contains 64 KB of drive space and has 16 KB of data residing on each drive in the stripe. In this case, the stripe size is 64 KB and the strip size is 16 KB. You can set the strip size to 8 KB, 16 KB, 32 KB, 64 KB, 128 KB, 256 KB, 512 KB, and 1024 KB. A larger strip size produces higher read performance. If your computer regularly performs random read requests, choose a smaller strip size. The default is 64 KB.

— Access Policy: Select the type of data access that is allowed for this virtual drive.

RW: Allow read/write access.

Read Only: Allow read-only access. This option is the default setting.

Blocked: Do not allow access.

— Read Policy: Specify the read policy for this virtual drive.

Normal: This option disables the read ahead capability. This option is the default setting.

Ahead: This option enables read ahead capability, which allows the controller to read sequentially ahead of requested data and to store the additional data in cache memory, anticipating that the data will be needed soon. This option speeds up reads for sequential data, but there is little improvement when accessing random data.

NOTE The WebBIOS Configuration Utility shows the maximum available capacity while creating the RAID 10 drive group. In version 1.03 of the utility, the maximum size of the RAID 10 drive group is the sum total of the two RAID 1 drive groups. In version 1.1, the maximum size is the size of the smaller drive group multiplied by 2.




— Write Policy: Specify the write policy for this virtual drive.

Always Write Back: In Always Write Back mode, the controller sends a data transfer completion signal to the host when the controller cache has received all of the data in a transaction. This setting is recommended in Standard mode.

Write Through: In Write Through mode, the controller sends a data transfer completion signal to the host when the drive subsystem has received all of the data in a transaction. This option is the default setting.

Write Back with BBU: Select this mode if you want the controller to use Write back mode but the controller has no BBU or the BBU is bad. If you do not choose this option, the controller firmware automatically switches to Write through mode if it detects a bad or missing BBU.

— IO Policy: The IO policy applies to reads on a specific virtual drive. It does not affect the read ahead cache.

Direct: In Direct I/O mode, reads are not buffered in cache memory. Data is transferred to the cache and the host concurrently. If the same data block is read again, it comes from cache memory. This option is the default setting.

Cached: In Cached I/O mode, all reads are buffered in cache memory.

— Drive Policy: Specify the drive cache policy.

Enable: Enable the drive cache.

Disable: Disable the drive cache. This option is the default setting.

NoChange: Leave the current drive cache policy as is.

— Disable BGI: Specify the Background Initialization (BGI) status.

No: Leave background initialization enabled. This option means that a new configuration can be initialized in the background while you use WebBIOS to do other configuration tasks. This option is the default setting.

Yes: Select Yes if you do not want to allow background initializations for configurations on this controller.

— Select Size: Specify the size of the virtual drive in MB, GB, or TB. Usually, this would be the full size for RAID 10 shown in the Configuration panel on the right. You can specify a smaller size if you want to create other virtual drives on the same drive group.

— Update Size: Click Update Size to update the Select size field value for the selected RAID levels.

14. Click Accept to accept the changes to the virtual drive definition.

A confirmation dialog appears.


— To confirm your changes, click Yes.— To undo the changes, select the virtual drive, and click Reclaim.

16. After you finish defining the virtual drives, click Next.

The Configuration Preview dialog appears, as shown in Figure 51.

CAUTION You can use Always Write Back mode with or without a BBU. Use either a battery to protect the controller cache, or an uninterruptible power supply (UPS) to protect the entire system. If you do not use a battery or a UPS and a power failure occurs, you risk losing the data in the controller cache.




Figure 51 RAID 10 Configuration Preview Dialog

17. Check the information in the Configuration Preview.


— If the virtual drive configuration is acceptable, click Accept to save the configuration. — To end the operation and return to the WebBIOS main menu, click Cancel. — To return to the previous dialogs and change the configuration, click Back.

19. If you accept the configuration, click Yes at the prompt to save the configuration.

Another confirmation for initialization appears.


— Click No to view the WebBIOS main menu.— Click Yes, and the initialization process takes place, and the WebBIOS Config Utility Virtual Drive

dialog appears.

4.5.2.7 Using Manual Configuration: RAID 50

RAID 50 provides the features of both RAID 0 and RAID 5. RAID 50 uses both distributed parity and drive striping across multiple drive groups. It provides high data throughput, data redundancy, and very good performance. It is best implemented on two RAID 5 drive groups with data striped across both drive groups. Though multiple drive failures can be tolerated, only one drive failure can be tolerated in each RAID 5 level drive group.

RAID 50 is appropriate when used with data that requires high reliability, high request rates, high data transfer, and medium-to-large capacity.

When you select Manual Configuration and click Next, the Drive Group Definition dialog appears. You use this dialog to select drives to create drive group.

1. Press and hold the Ctrl key while selecting at least three unconfigured good drives in the Drives panel on the left.

2. Click Add To Array to move the drives to a proposed drive group configuration in the Drive Groups panel on the right.


3. Click Accept DG to create a first drive group.

An icon for a second drive group appears in the right panel.


figure 47 raid 00 configuration preview dialog...18. check the information in the configuration...

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