RAID Level Migration (RLM) Overview

RAID level migration is the process of converting one RAID configuration to another. When you migrate a unit to a different configuration, the user data on it is redistributed to the format of the new configuration. This data redistribution process is a background task, similar to the rebuild or verify processes.

Figure "RAID Level Migration Example" shows an example of how data is reconfigured during a migration. In this example, the migration is from a 4-drive RAID 0 to a 6-drive RAID 5, with both having the same stripe size. As can be seen, every piece of user data is moved from its original physical location.

RAID Level Migration Example

Typically, a unit is reconfigured with the same or more storage capacity. Sometimes additional drives are added. The following table shows valid reconfigurations, some of which will require the addition of more drives.

Valid Migration Paths

Source	Destination
	R0	R1	R5	R10	R50	Single	JBOD	Spare
R0	Yes	No	Yes	Yes	Yes	No	No	No
R1	Yes	No	Yes	Yes	Yes	Yes	No	No
R5	Yes	No	Yes	Yes	Yes	No	No	No
R10	Yes	No	Yes	Yes	Yes	No	No	No
R50	Yes	No	Yes	Yes	Yes	No	No	No
Single	Yes	Yes	Yes	Yes	Yes	No	No	No
JBOD	No	No	No	No	No	No	No	No
Spare	No	No	No	No	No	No	No	No

Warning: Never split a mirror into 2 single (identical) drives that you are booted or mounted from. The file system on the second drive will be left in an unclean state since any pending writes cannot be completed after the split occurs.

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Related Topics

Changing An Existing Configuration

Changing RAID Level

Expanding Unit Capacity

Informing the Operating System of Changed Configuration

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