Nortel Networks BCM200, 400 4.0 manual RAID disk mirroring

Chapter 19 System monitoring and troubleshooting 221

Table 79 Status LED description (Sheet 2 of 2)

Status LED
description	Description	Maintenance action
Flashing green	Drives may not be identical.	Indicates a data comparison fault. For 3.5x
		version software (and later), the system
		automatically adapts for data mismatches
		and unequal hard disk capacity. The system
		attempts a disk mirror rebuild.
		The system continues to operate. Nortel
		recommends that you perform the following:
		• Examine the status report to determine
		which hard disk has the smaller
		capacity.
		• Replace the smaller hard disk (primary
		master or mirror master) with a new hard
		disk of the correct size. Equipment
		provided by Nortel assures correct hard
		disk capacity requirements.
Solid red	• Drives are not in mirror mode.	Immediate action required:
	• Missing or bad hard disk (1 or both).	• Check the RAID operational status.
	• Occurs on newly installed RAID card	• Check hard disk power and data
	or hard disk (first 10 min). SSM	connections.
	begins mirror process — no action	• Replace the hard disk if required.
	required.
		• Initialize the BCM system.
	• SSM determined BCM is not
	initialized (core software, WAN,
	MSC).

RAID disk mirroring

The RAID configuration (RAID 1) uses two hard disks. One disk is called the primary master hard disk and the other is called the mirror master hard disk. Disk mirroring is the process of ensuring the data from one hard disk is identical to the other.

Disk mirroring provides data redundancy and fault tolerance should one disk fail. The mirror hard disk continues to function and the system operates without any loss of service if the primary master hard disk fails. Similarly, the primary master hard disk continues to function and the system operates without any loss of service if the mirror hard disk fails.

Over time, configuration or load data on your system changes. The system writes the new data to both disks simultaneously.

Note: Under some conditions, the system will halt operating if a hard disk fails during a read/write to the operating system (O/S) portion of the hard disk. To continue operation, reboot the system.

The RAID configuration disk replacement scenarios are as follows:

BCM200/400 4.0 Installation and Maintenance Guide