Dell PowerEdge: How to change the RAID level of a Virtual Disk

Dell PowerEdge: How to change the RAID level of a Virtual Disk


Note: This article is part of the Server Tutorials: "Raid and Disks" available here.


An online virtual disk can be reconfigured in ways that expand its capacity and/or changes its RAID level.
Note: The controller changes the write cache policy of all virtual disks undergoing an RLM/OCE to Write-Through until the RLM/OCE is complete.
Note: Spanned virtual disks such as RAID 10, 50, and 60 cannot be reconfigured.
Re-configuring virtual disks typically impacts disk performance until the reconfiguration operation is complete.

Online Capacity Expansion (OCE) can be done in two ways:
  • If there is a single virtual disk in a disk group and free space is available, the virtual disk’s capacity can be expanded within that free space.
  • If a virtual disk is created and it does not use the maximum size of the disk group, free space is available.
Free space is also available when a disk group’s physical disks are replaced by larger disks using the Replace Member feature. A virtual disk's capacity can also be expanded by performing an OCE operation to add more physical disks.


RAID Level Migration (RLM) refers to changing a virtual disk’s RAID level. Both RLM and OCE can be done at the same time so that a virtual disk can simultaneously have its RAID level changed and its capacity increased. When an RLM/OCE operation is complete, a reboot is not required. The source RAID level column indicates the virtual disk RAID level before the RLM/OCE operation and the target RAID level column indicates the RAID level after the RLM/OCE operation.
Note: This feature is available since iDRAC 9 generation if you have a supported PERC(9 and 10).

To extend a virtual disk, add similar disk in the backplane and then reconfigure the virtual disk.

Reconfiguration can be done by following these steps:
  • In the PERC BIOS menu (at startup), once the Virtual Disk is selected press F2, then Reconfigure.
  • In OMSA, System > Storage > PERC > Virtual Disk > select Reconfigure in the dropdown menu.

Possible RAID Level Migrations:

Source RAID Target RAID Required Number of PDs(Beginning) Number of PDs(End) Capacity Expansion Possible Description
RAID 0 RAID 0 1 2 or more Yes Increases capacity
RAID 0 RAID 1 1 2 No Converts non-redundant virtual disk into a mirrored virtual disk by adding one disk.
RAID 0 RAID 5 1 or more 3 or more Yes At least one drive needs to be added for distributed parity data.
RAID 0 RAID 6 1 or more 4 or more Yes At least two drives need to be added for dual distributed parity data.
RAID 1 RAID 0 2 2 or more Yes Removes redundancy while increasing capacity.
RAID 1 RAID 5 2 3 or more Yes Maintains redundancy while doubling capacity.
RAID 1 RAID 6 2 4 or more Yes Two drives are required to be added for distributed parity data.
RAID 5 RAID 0 3 or more 3 or more Yes Converts to a non-redundant virtual disk and reclaims disk space used for distributed parity data.
RAID 5 RAID 5 3 4 or more Yes Increases capacity by adding disks.
RAID 5 RAID 6 3 or more 4 or more Yes At least one drive needs to be added for dual distributed parity data.
RAID 6 RAID 0 4 or more 4 or more Yes Converting to a non-redundant virtual disk and reclaiming disk space used for distributed parity data.
RAID 6 RAID 5 4 or more 4 or more Yes Removing one set of parity data and reclaiming disk space used for it.
RAID 6 RAID 6 4 5 or more Yes Increases capacity by adding disks.
Note: If the controller already contains the maximum number of virtual disks, you cannot perform a RAID level migration or capacity expansion on any virtual disk.



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Article ID: SLN305744

Last Date Modified: 04/02/2019 07:25 AM


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