Dell PowerEdge RAID Controller H710 - Manual (Page 46)

Break Mirror
A Break Mirror operation is an operation that can be performed only on RAID1 arrays. It provides a way to 'split' the
mirror and spin-down one of the hard disks, which can then be imported into the configuration of a different PERC H310,
H710, H710P, or H810 controller. This can be a useful way to:
• Create a disk image that can be imported and booted on a different system.
• Assist in software or configuration testing, where half of the mirror can be removed to ensure configuration
consistency.
NOTE: The Break Mirror operation is not available within the booted operating system environment. It is
only available in the BIOS ( ) utility and the UEFI RAID configuration utility.
Break Mirror In BIOS Configuration Utility
The RAID1 VD that you are to split must be in an optimal state, and it cannot be running any other background tasks.
To use the Break Mirror feature from the BIOS Configuration Utility ( ), perform the following steps:
1. During boot up, press when prompted by the BIOS screen. If there is more than one controller in the
system, choose the controller.
The VD Mgmt screen is displayed by default.
2. Highlight the appropriate Disk Group.
3. Press to display the available actions.
4. Choose Break Mirror and press .
A dialog is displayed describing the operation and asking if you are sure you want to perform the operation.
5. Select Yes to continue.
The exported disk (exporting configuration) spins down and the hard drive status LED starts flashing to identify
which drive must be pulled.
The remaining disk (exporting configuration) is in a degraded state until the missing member is replaced or rebuilt.
If there are any Global or Dedicated Hot Spare assigned which fulfills the rebuild requirements for the degraded
RAID1 disk, a rebuild starts automatically. If there is no Hot Spare assigned, then a Hot Spare that meets all the
requirements for the VD must be assigned before the rebuild starts.
NOTE: Importing a Broken Mirror is the same as importing a Foreign configuration. See the topic Importing Or
Clearing Foreign Configurations Using The VD Mgmt Menu . The imported VD is in a degraded state until the
missing member is rebuilt.
Managing Preserved Cache
If a virtual disk becomes offline or is deleted because of missing physical disks, the controller preserves the dirty cache
from the virtual disk. The preserved dirty cache, known as pinned cache, is preserved until you import the virtual disk or
discard the cache.
NOTE: Certain operations, such as creating a new virtual disk, cannot be performed if preserved cache exists. You
have to enter the BIOS Configuration Utility ( ) to resolve the situation before you boot to the operating
system. Messages are displayed notifying you that you must enter the BIOS Configuration Utility ( ) to
discard the preserved cache or import the virtual disks with the preserved cache.
CAUTION: If there are any foreign configurations, it is strongly advised that you import the foreign configuration
before you discard the preserved cache. Otherwise, you might lose data that belongs with the foreign
configuration.
46