Important Terms And Concepts - HP XP20000/XP24000 User Manual

NOTE: User accounts registered to HP Systems Insight Manager are different from the user
accounts for Remote Web Console. To implement single sign-on, you do not need to register the
user accounts of HP Systems Insight Manager to Remote Web Console. If a user logs in with both
ways (to log in directly to Remote Web Console, and to log in with single sign-on from HP Systems
Insight Manager), make sure that the operation privilege of the user account registered to HP
Systems Insight Manager matches the operation privilege of Remote Web Console. If they do not
match, the user has only the operation privilege of HP Systems Insight Manager.

Important Terms and Concepts

The Remote Web Console user should be familiar with the following terms and concepts:
Disk controller frame. The storage system has one disk controller frame that controls all data
access and storage operations. The storage system provides up to 256 logical CUs and
supports 3990-6, 3990-6E, 2105-F20, 2107, and open-systems controller emulation types.
For storage system program products, a maximum of 255 CUs are available.
The 3990-3 and 2105-E20 controller emulation types are not supported.
LDKC. The storage system controls CUs in groups of 256. This group is called an LDKC. There
is one LDKC for the storage system and the LDKC is numbered 0.
One LDKC controls up to 256 CUs; however, only 255 CUs are available for the storage
system program products. Therefore, up to 65,280 volumes are available for the storage
system 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
(three data and one 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. The storage system supports a maximum of 65,536 LDEVs. However, up to 65,280
volumes are available for the storage system program products.
An LDEV can be called a volume. An LDEV used by mainframe hosts can be called a device
or LVI. An LDEV used by open-system hosts can be called a device (for example, SCSI disk
device, raw device) or a LU.
Only up to 32,640 LDEVs are available for some of the storage system functions or program
products.
LU. An LDEV used by open-system hosts is called an LU. An open-system LU on the Fibre
Channel interface can be mapped to one or more LDEVs.
CU. The storage system supports a maximum of 256 logical CUs numbered sequentially from
00-FF. Each CU controls up to 256 LDEVs. LDEVs within the storage system are accessed by
a combination of CU number (00-FF) and device number (00-FF).
However, the CU number FF is reserved for the RAID Manager operation. Therefore, the CUs
that can be used for the storage system program products operation are up to CU number FE.
This means that the number of CUs that can be used for the storage system program products
operation is 255 per LDKC at the maximum.
Table 5 (page 17)
16 About Remote Web Console Operations
shows an example of the device numbers for CU.