Hitachi MK-96RD621-08 - Manual (Page 25)

About Storage Navigator Operations 1-11
Hitachi Universal Storage Platform V/VM Hitachi Storage Navigator User’s Guide
Important Terms and Concepts
The Storage Navigator user should be familiar with the following terms and
concepts:
• Disk controller frame. The USP V/VM storage system has one disk
controller frame that controls all data access and storage operations. The
USP V/VM storage system provides up to 256 logical control units (CU) and
supports 3990-6, 3990-6E, 2105-F20, and 2107 controller emulation types.
For USP V/VM program products, a maximum of 255 CUs are available.
Note: The 3990-3 and 2105-E20 controller emulation types are not
supported.
• Logical disk controller frame (LDKC). The USP V/VM storage system
controls CUs in groups of 256. This group is called a logical disk controller
frame (LDKC). There is one LDKC for the USP V/VM storage system and the
LDKC is numbered zero (0).
One LDKC controls up to 256 CUs, however, only 255 CUs are available for
the USP V/VM program products. Therefore, up to 65,280 volumes are
available for the USP V/VM program products.
• Disk array frame. The disk array frame of the storage system contains
the storage components (hard disk drive arrays).
• Parity group. A parity group (also called array group) is a set of hard disk
drives that are treated as one group. For example, a RAID-5 3D+1P parity
group consists of four disk drives (3 data and 1 parity). A parity group
contains both user data and parity information, and the parity information
is used to automatically reconstruct the user data if one of the disk drives
in the parity group becomes unavailable.
• LDEV (logical device). The USP V/VM storage system supports a
maximum of 65,536 LDEVs. However, up to 65,280 volumes are available
for the USP V/VM program products.
An LDEV can be called a volume. An LDEV used by mainframe hosts can be
called a device, logical volume image (LVI). An LDEV used by open-system
hosts can be called a device (for example, SCSI disk device, raw device) or
a logical unit (LU).
Note: Only up to 32,640 LDEVs are available for some of the USP V/VM
functions or program products.
• LU (logical unit). An LDEV used by open-system hosts is called an LU. An
open-system LU on fibre-channel interface can be mapped to one or more
LDEVs.