Dell PERC 4/DC - Manual (Page 6)

Drive roaming occurs when the hard drives are changed to different channels on the same controller. When the drives are placed on different channels, the
controller detects the RAID configuration from the configuration information on the drives.
Configuration data is saved in both non-volatile random access memory (NVRAM) on the RAID controller and on the hard drives attached to the controller. This
maintains the integrity of the data on each drive, even if the drives have changed their target ID. Drive roaming is supported across channels on the same
controller, except when cluster mode is enabled.
Table 2 -4 lists the drive roaming features for the RAID controller.
Table 2-4. Features for Drive Roaming
Drive Migration
Drive migration is the transfer of a set of hard drives in an existing configuration from one controller to another. The drives must remain on the same channel
and be reinstalled in the same order as in the original configuration.
Hardware Architecture Features
Table 2 -5 displays the hardware architecture features for the RAID controller.
Table 2-5. Hardware Architecture Features
LED Operation
After you remove a physical drive and place it back in the slot for a rebuild, the LED blinks for the drive as it is being rebuilt.
NOTE: Drive roaming does not work if you move the drives to a new controller and put them on different channels. If you put drives on a new controller,
the controller must have a clear configuration. In addition, the drives must be on the same channel/target as they were on the previous controller to
keep the same configuration.
NOTE: Before performing drive roaming, make sure that you have first powered off both your platform and your drive enclosure.
Specification PERC 4/SC PERC 4/DC PERC 4e/DC
Online RAID level migration Yes Yes Yes
RAID remapping Yes Yes Yes
No reboot necessary after capacity extension Yes Yes Yes
NOTE: Drive roaming and drive migration cannot be supported at the same time. PERC can support either drive roaming or drive migration at any one
time, but not both at the same time.
Specification PERC 4/SC PERC 4/DC PERC 4e/DC
Processor Intel GC80302 (Zion Lite) Intel GC80303 (Zion) 80332
SCSI controller(s) One LSI53C1020 Single SCSI
controller
One LSI53C1030 Dual SCSI
controller
One LSI53C1030 Dual SCSI
controller
Size of flash memory 1 MB 1 MB 1 MB
Amount of NVRAM 32 KB 32 KB 32 KB
Hardware exclusive OR (XOR) assistance Yes Yes Yes
Direct I/O Yes Yes Yes
SCSI bus termination Active or LVD Active or LVD Active or LVD
Double-sided dual inline memory modules (DIMMs) Yes Yes Yes
Support for hard drives with capacities of more than
eight gigabytes (GB)
Yes Yes Yes
Hardware clustering support on the controller No Yes Yes