Dell UCPM-800 Physical Disk Roaming

Both Consistency Check (CC) and Background Initialization (BGI) correct parity errors. However, CC

reports data inconsistencies through an event notification, whereas BGI is an automatic process.

BGI does not run on RAID 0 virtual disks. You cannot disable BGI permanently. If you cancel BGI, it

automatically restarts within five minutes. Unlike full or fast initialization of virtual disks, BGI does not clear

data from the physical disks. CC or BGI typically causes some loss in performance until the operation

completes.

NOTE: In systems with Fault Tolerant Shared PERC 8 card configuration, in the event of controller

failover, a BGI starts automatically on each virtual disk. If a BGI operation was in progress at the time

of controller failover, then the BGI resumes on the new active Shared PERC 8 controller from the

last recorded checkpoint.

CAUTION: Performing a full initialization on a virtual disk overwrites all blocks and destroys any

data that previously existed on the virtual disk. Full initialization of a virtual disk eliminates the

need for the virtual disk to undergo a BGI. Full initialization can be performed after the creation

of a virtual disk.

During full initialization, the host is not able to access the virtual disk. You can start a full initialization on a

virtual disk in the CMC.

In the event of a controller failover in systems with Fault Tolerant Shared PERC 8 card configuration, full

initialization does not continue on the active controller. You must start full initialization again through

CMC. For more information on virtual disk initialization, see the Dell Chassis Management Controller for

Dell PowerEdge VRTX User’s Guide at dell.com/poweredgemanuals and the Dell Chassis Management

Controller for Dell PowerEdge VRTX Online Help.

In the event of controller failover or system reboot during a full initialization, the operation terminates

and a BGI begins on the virtual disk.

NOTE: Performing a full initialization prevents a BGI from starting automatically on virtual disks.

A fast initialization on a virtual disk overwrites the first and last 8 MB of the virtual disk, clearing any boot

records or partition information. The operation takes only 2-3 seconds to complete and is recommended

when you are recreating virtual disks. You can perform a fast initialization in the CMC.

NOTE: A BGI starts five minutes after the Fast Initialization is completed.

Physical Disk Roaming

Physical disk roaming is moving the physical disks from one backplane slot to another on the same

controller. The controller automatically recognizes the relocated physical disks and logically places them

in the virtual disks that are part of the disk group. You can perform disk roaming only when the system is

turned off.