Product manual

Chapter 7: Technology Background
275
RAID Level Migration
The term “Migration” means either or both of the following:
• Change the RAID level of a logical drive.
• Expand the storage capacity of a logical drive.
On VTrak, RAID level migration is performed on the disk array but it applies to the
logical drives. Migration does not disturb your data. You can access the data
while the migration is in progress. When migration is done, your disk array has a
different RAID level and/or a larger capacity.
Migration Requirements
The following conditions affect RAID level migration:
• The disk array and logical drive must show a green check icon.
• The Target disk array may require more physical drives than the Source disk
array.
• If the Target disk array requires an EVEN number of physical drives but the
Source disk array has an ODD number, ADD a physical drive as part of the
migration process.
• You cannot reduce the number of physical drives in your disk array, even if
the Target disk array requires fewer physical drives than the Source disk
array.
• RAID 1 (mirroring) works with two drives only. Only a single-drive RAID 0
disk array can migrate to RAID 1. Other RAID Levels use too many drives to
migrate.
• You cannot migrate a disk array when it is Critical or performing activities
such as Synchronizing, Rebuilding, and PDM.
• For RAID 6 or RAID 60, you can only migrate between these two RAID
levels. Destination RAID 60 axles can have up to 16 physical drives. Other
limitations might apply.
Source and Target RAID Levels
The tables on the following pages show the migration options for each source
logical drive by its RAID level. The available target RAID levels are shown with
their requirements.