HP StorageWorks 2000 Modular Smart Array Reference Guide (481599-003, August 2008)

64 HP StorageWorks 2000 Family Modular Smart Array reference guide • August 2008
The following table specifies the minimum and maximum numbers of disk drives
supported for each RAID level. For more information about RAID levels, see
Appendix B.
When you create a virtual disk you can also create volumes within it. A volume is a
logical subdivision of a virtual disk, and can be mapped to host ports for access by
data hosts. The storage system only presents volumes, not virtual disks, to data
hosts.
You can create a virtual disk that has one volume or multiple volumes. Single-
volume virtual disks work well in environments that need one large, fault-tolerant
storage space for data on one server. A large database accessed by users on a single
server that is used only for that application is an example. Multiple-volume virtual
disks work well when you have very large disk drives and you want to make the
most efficient use of disk space for fault tolerance (parity and spares). However, I/O
to multiple volumes in the same virtual disk can slow system performance.
Table 3-1 Number of Disk Drives Supported for Each RAID Level
RAID Level
Min.
Drives
Max.
Drives Note
Non-RAID 1 1
0 2 16
1 2 2 To create a mirror with more than two drives, use
RAID 10.
3 3 16
5 3 16
6 4 16
10 4 16 RAID 10 must have the same, even number of drives
in each sub-vdisk. Each sub-vdisk can have 2–8
drives. The total number of drives is a multiple of
the number of drives in each sub-vdisk.
50 6 32 RAID 50 must have the same number of drives in
each sub-vdisk. Each sub-vdisk can have 3–16
drives. The total number of drives is a multiple of
the number of drives in each sub-vdisk.