Areca 24/4 Internal/External Port Pcie 3.0 12 Gb/s SAS/SATA Raid Controller 2Gb Cache - Manual (Page 164)

WEB BROWSER-BASED CONFIGURATION
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6.6.4.2 Volume Set Migration
Migrating occurs when a volume set is migrating from one RAID
level to another, when a volume set strip size changes, or when
a disk is added to a RAID set. Migration state is displayed in the
volume state area of the “RAID Set Hierarchy” screen.
Note:
1. If the volume is RAID level 30, 50, or 60, you can not
change the volume to another RAID level. If the volume
is RAID level 0, 1, 10(1E), 3, 5, or 6, you can not
change the volume to RAID level 30, 50, or 60.
2. Power failure may damage the migration data. Please
backup the RAID data before you start the migration
function.
6.6.4.3 Volume Write Protection
When "Volume Write Protection" is enabled on the "Modify
Volume Set", host commands fail if they are issued to a volume
in that RAID controller and attempt to modify a volume's data
or attributes. Volume Write Protection is used primarily for
customer-initiated disaster recovery testing.