HP NetRAID-4M Configuration and Upgrade Guide (Release 5)

Chapter 10 Glossary
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File System Expansion
A term used to describe extending a file system (a feature of Windows 2000), such
as NTFS. In NT 4.0, no volume extension was needed to do this. In Windows 2000,
it appears that volume extension, when NTFS is on a volume, is the only way to
extend a file system.
Free Space
The HP NetRAID-4M works on the concept of “free space” rather than dedicated
spare disks. A failover space not currently used for storage is available to be
assigned as failover space for another container or even as a container itself. With
conventional array solutions, spare disks are assigned on a one-to-one basis for each
redundant array. The NetRAID-4M’s controller management software’s ability to
view and manage storage as a pool of free space allows you to assign spare disks on
a one-to-many basis. Because each spare disk is not dedicated to a single fault-
tolerant container, multiple containers can share the same spare space. This powerful
method of flexible spare space assignment can significantly reduce the number of
dedicated spare disks needed to protect against disk failures. If the HP NetRAID-4M
detects an unrecoverable error during I/O on a redundant container, it checks for an
available spare disk that has sufficient free space to handle the rebuild, and starts the
rebuild process.
Graphical User Interface (GUI)
The graphical user interface for the NetRAID-3Si, 1M and 2M is the NetRAID
Assistant and for the NetRAID-4M, it is FAST.
Logical Drive (Container)
A group of independent drives that behave as one big drive back to the NOS,
providing performance and fault tolerance advantages.
Logical Unit Number (LUN)
In SCSI, LUN refers to a physical mechanism behind the SCSI ID. In the case of
RAID, a maximum of 15x8=120 logical drives can be presented back to the
operating system.
The number of logical drives that can be handled is also NOS-dependent. NT only
handles 24.