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Service Hints & Tips

Document ID: MCGN-3K2K4T

Netfinity Manager - RAID drive synchronization

Applicable to: World-Wide

This document includes answers to the following questions:
What does synchronization do and why is it important?
How do I manually synchronize an array using Netfinity Manager 4 or 5?
Can I schedule Netfinity Manager to automatically synchronize my array at a certain time?

Question:
What does synchronization do and why is it important?

Answer:
To begin, please note that only RAID 5 arrays support synchronization. RAID 5 uses parity information to protect data across 3 or more hard drives. While this parity information is not a backup copy of the data, it can be used, along with the data on the remaining drives, to rebuild the data from any one drive in the array should that drive fail. In order for the parity information to be useful, the RAID controller must be able to access data from ALL of the other drives. If it tries to read from one of the working drives and encounters a problem, then the data that is rebuilt on the failed drive may not be correct or the rebuild will fail to complete successfully. This is usually caused by a bad sector on the drive. A single bad sector does not cause a drive to fail, but makes the data written in that sector unusable. If this happens in an array that is not in a critical state, the RAID controller simply rebuilds the data that should be in that sector using the parity information, stores it in another place on the drive, then marks the sector bad. However, when one drive is already down, the array is critical, and this is not possible.

That's where synchronization comes in. Synchronization forces the controller to examine all the sectors on all of the drives in the array to make sure they can be accessed correctly. If it reaches a bad sector, it recreates the data stored in that sector using the parity information, moves the data to another part of the drive, verifies that it can now access the data, updates the parity information to match the new location of the data and marks the sector bad. Thus in the event of a drive failure, the RAID controller will use the parity information to successfully rebuild all the data from the failed drive correctly.

Question:
How do I manually synchronize an array using Netfinity Manager 4 or 5?

Answer:
The procedure for initiating synchronization manually in Netfinity Manager 4 and 5 is:

1. Start Netfinity Manager's Service Manager and double-click on the RAID Manager Icon.

2. A screen will appear showing a graphical representation of the host CPU, the RAID adapter(s), and all of the virtual devices (logical drives) defined on the adapter(s). Right-click on the drive you wish to synchronize.

3. A menu will appear, click on Virtual Functions on this menu.

4. Another menu will appear, click on Synchronize Virtual Drive on this menu. NOTE: If the option to Synchronize Virtual Drive is grayed out, then the virtual drive you are trying to synchronize is not RAID level 5. Only RAID 5 arrays support synchronization.

5. A confirmation will appear stating that synchronization may take an extremely long time and system performance may be degraded while the operation is running. For this reason, try to schedule RAID synchronization during the low usage periods for the server. Click Yes to begin synchronization.

Question:
Can I schedule Netfinity Manager to automatically synchronize my array at a certain time?

Answer:
Netfinity Manager 5 allows you to schedule synchronization at a predetermined time. Netfinity Manager 4 does not support this feature. To schedule synchronization in Netfinity Manager 5, do the following:

1. Start Netfinity Manager's Service Manager and double-click on the Event Scheduler icon.

2. A screen appears listing all of the currently scheduled events (if any). Click on the New button at the bottom left of this screen.

3. On the next screen, type in a name for the event (this can be anything) and select Synchronize All RAID Drives in the Tasks box.

4. Click on either the groups or systems in the Schedule By box. These options allow you to select the machine(s) that will participate in the synchronization event by either specifying a predefined group or selecting individual machines by name.

NOTE:
If there are no systems or groups to choose from and you are unsure how to define groups or discover systems, refer to your Netfinity Manager manual.

5. After selecting the machine(s) you want to participate in the synchronization, click on the Schedule button at the bottom of the screen.

6. The next screen allows you to choose when the synchronization will occur. Choose a schedule frequency (one time, daily, weekly, etc.) by clicking one of the buttons in the Schedule Frequency box.

NOTE:
You can click on the help button at the bottom right corner of the screen for detailed information about any option on this screen.

7. Use the Schedule Date and Time box to set the time of the first synchronization. Options in the date and time box that contain an * are either not applicable or have not yet been modified.

8. When you are done scheduling the event, click the save button. You will then return to the Schedule Service screen and the new event should be listed as scheduled.

	Search Keywords	NetFinity Manager, RAID, synchronize, schedule
	Hint Category	Netfinity Manager
	Date Created	16-07-97
	Last Updated	01-12-98
	Revision Date	17-11-99
	Brand	IBM PC Server
	Product Family	Systems Management
	Machine Type	Various
	Model	Various
	TypeModel
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