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

Chapter 10 Glossary
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In the horizontal dimension, the RAID (even) parity information detects an error. In
the vertical dimension, the drive read/write electronics also detects an error.
Together, the error is located and corrected.
RAID free space
The HP NetRAID-4M works on the concept of “free space” rather than dedicated
spare disks. A fail over space not currently used for storage is available to be
assigned as fail over 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 controller management software is able to view and manage
storage as a pool of free space allows spare disks to be assigned 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.
RAID initialize
This command writes a controller signature on a drive. All new SCSI disks must be
initialized to prepare them for use in a container. In the NetRAID-4M menu, disks
are initialized using the Disk menu or the Initialize button on the Container Creation
Wizard (and Container Reconfiguration Wizard).
Table 10-1.
Drive A Drive B Drive C Drive D Drive E Drive F Drive G Drive H parity status
stripe 0 10101 0100OK
stripe 1 1100
V
1111bad
stripe 2 01001 1001OK
drive OK OK OK OK bad OK OK OK OK OK