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In Volume Migration operations (optimizing LDEV allocation), you cannot migrate an array group within a
combined/striped group to another group. Volume Migration migrates all LDEVs in an array group to another
array group.
RAID 28+4 - Vertical Striping
Raid 28+4 or Raid 14+2 - vertical striping is also known as Raid 5 concatenation in which two or four RAID5
(7D+1) parity groups are concatenated. The data and parity is distributed and arranged in 16 or 32 drives. The
V05 code has two parity group concatenation and V06 code has full four Raid5 (7+1) concatenation. The main
advantage of this type of concatenation is that in case of major parity group bottleneck you can increase size of
parity group and spread load by increasing twice or four times number of drives. More spindles better the
performance. The only caveat you need to consider is in case of two drives blocked/failure as large numbers of
Ldev are arranged in comparison to RAID5 (7+1) and formating time.
RAID-Level Intermix
RAID technology provides high availability capability for the disk drives of the ST9985V. The cache
management algorithms enable the ST9985V to stage up to one full RAID stripe of data into cache ahead of the
current access to allow subsequent access to be satisfied from cache at host channel transfer speeds.
The ST9985V supports RAID-1, RAID-5, RAID-6, and intermixed RAID-level configurations, including
intermixed array groups within an array domain. illustrates an intermix of RAID levels. All types of array
groups (RAID-5 3D+1P, 7D+1P; RAID-1 2D+2D, 4D+4D; RAID-6 6D+2P) can be intermixed under one
DKA pair.
Hard Disk Drive Intermix
All hard disk drives (HDDs) in one array group (parity group) must be of the same capacity and type. Different
HDD types can be attached to the same DKA pair.
Note: For the latest information on available HDD types and intermix requirements, please contact your Sun
Microsystem Systems account team.
Device Emulation Intermix
This diagram illustrates an intermix of device emulation types. The ST9985V supports an intermix of all
device emulations on the same DKA pair, with the restriction that the devices in each array group have the
same type of track geometry or format.
The Virtual LVI/LUN (also called CVS) function enables different logical volume types to coexist. When
Virtual LVI/LUN is not being used, an array group can be configured with only one device type (for example,
3390-3 or 3390-9, not 3390-3 and 3390-9). When Virtual LVI/LUN is being used, you can intermix 3390
device types, and you can intermix OPEN-x device types, but you cannot intermix 3390 and OPEN device
types.
Note: For the latest information on supported LU types and intermix requirements, please contact your Sun
Microsystems Data Systems account team.
Just the Facts
October 2007
48
Sun Confidential – For Internal Use and Authorized Partner Use Only