Degraded RAID Array

MARS-100E and larger appliances feature Redundant Array of Independent Disks (RAID) to provide protection against data loss. RAID allows MARS to lose a hard drive without losing data, or even requiring a reboot.

A degraded RAID array can occur when the data on a hard disk is damaged. This usually occurs when an appliance is not cleanly shut down or rebooted, such as when power is lost. Power surges and drops (also known as brownouts) can also cause damage to your hard disks. You can help prevent these unpleasant problems by using a high-quality UPS.

When you have a degraded RAID array, MARS sends an e-mail notification to the pnadmin user, if that user has an e-mail address defined. MARS also changes the LED for the degraded drive from green to yellow. If you reboot MARS, the RAID status will display onscreen if you have a monitor connected.

If you do not have the pnadmin e-mail address configured within MARS, you should take the time to do that right away. Figure 9-1 shows the field to complete within User Manager, which you can reach by clicking the MANAGEMENT button, and then clicking the User Management tab.

From the command-line interface (CLI), you can use the raidstatus command to see whether all disks are operating properly. This command shows you the current status of each of the hard disks installed in the MARS-100E and larger appliances. The MARS-50 and below do not use RAID.

Figure 9-2 shows the output of the raidstatus command with degraded status.

Figure 9-1 Enter E-Mail Address for pnadmin User

Figure 9-1 Enter E-Mail Address for pnadmin User

Figure 9-2 RAID Array in Degraded Status

When a hard disk is in a degraded state, you can attempt to correct this state by using the hotswap command. Be careful when using this command. In fact, this is one time when you should have the Cisco TAC on the phone. The basic idea of correcting this problem is pretty simple. However, the syntax for doing it is not intuitive.

Consider the following example.

On a MARS-200, the raidstatus command shows that physical port 1 is in a degraded state. You decide to try rebuilding the drive with the hotswap command. The syntax for this command is as follows:

hotswap <add|remove> disk

You enter: hotswap remove 1

Now, you realize that you've made a mistake, because the raidstatus command now shows that physical port 1 is still in a degraded state, and physical port 7 has been removed from the system.

The port or disk numbers used by the two commands are different from each other. Normally, the order in which the drives are displayed with the raidstatus command defines the disk number used by the hotswap command, although this can also differ with some appliances. This is a good reason to work with the Cisco TAC when fixing a degraded disk.

To correct the problem you've accidentally caused by degrading a new disk, type the following:

hotswap add 1

It will take several minutes to correct the problem, and then you can correct the original degraded disk by typing the following:

hotswap remove 7 hotswap add 7

Continue reading here: Unknown Reporting Device IP

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