Dell PowerEdge RAID Controller 6i - Manual (Page 34)

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About PERC 6 and CERC 6i Controllers
Reconfiguring Virtual Disks
There are two different methods to reconfigure RAID virtual disks — RAID Level
Migration and Online Capacity Expansion. RAID Level Migrations (RLM)
involve the conversion of a virtual disk to a different RAID level and Online
Capacity Expansions (OCE) refer to increasing the capacity of a virtual disk by
adding drives and/or migrating to a different RAID level. When a RLM/OCE
operation is complete and reboot is not necessary. For a list of possible RAID level
migrations and whether or not a capacity expansion is possible in that scenario,
see Table 3-2.
The source RAID level column indicates the virtual disk level before the
RAID level migration and the target RAID level column indicates the RAID
level after the operation is complete.
NOTE:
If you configure 64 virtual disks on a controller, you cannot perform a RAID
level migration or capacity expansion on any of the virtual disks.
NOTE:
The controller changes the write cache policy of all virtual disks undergoing
a RLM/OCE to Write-Through until the RLM/OCE is complete.
Table 3-2. RAID Level Migration
Source
RAID
Level Target
RAID
Level Required
Number of
Physical
Disks
(Beginning) Number of
Physical
Disks
(End) Capacity
Expansion
Possible Description
RAID 0 RAID 1 1 2 No Converting non-redundant
virtual disk into a mirrored
virtual disk by adding one
drive.
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 Yes Removes redundancy while
doubling capacity.
Dell_PERC6.1_UG.book Page 34 Wednesday, April 15, 2009 4:18 PM