Asus PCI-DA2200 - Manual (Page 257)

ASUS GUI RAID Manager: Array Management
4-6 4.2 Operation without Spare Drives
same logical drive. A defective drive must be promptly
replaced and data rebuilt.
CAUTION: When performing hot-swapping, be sure to
remove only the defective drive. Removing the wrong drive
will result in unrecoverable data loss. Use the Enclosure or
Physical Drives window to locate the exact location of the
failed drive.