Dell PowerEdge RAID Controller H700 - Manual (Page 173)

Glossary 173
Striping
Disk striping writes data across all physical disks in a virtual disk. Each stripe
consists of consecutive virtual disk data addresses that are mapped in fixed-size
units to each physical disk in the virtual disk using a sequential pattern.
For example, if the virtual disk includes five physical disks, the stripe writes data
to physical disks one through five without repeating any of the physical disks.
The amount of space consumed by a stripe is the same on each physical disk.
The portion of a stripe that resides on a physical disk is a stripe element. Striping
by itself does not provide data redundancy. Striping in combination with parity
does provide data redundancy.
U
User-Bound Security Configuration
A configuration in which the controller encrypts the security key with the
passphrase and then stores it in the NVData. The controller cannot decrypt
the security key without the passphrase. The controller prompts the user for
the passphrase on every boot.
V
Virtual Disk
A virtual disk refers to storage created by a RAID controller from one or more
physical disks. Although a virtual disk may be created from several physical
disks, it is seen by the operating system as a single disk. Depending on the RAID
level used, the virtual disk may retain redundant data in case of a disk failure.
W
Write-Back
In Write-Back caching mode, the controller sends a data transfer completion
signal to the host when the controller cache has received all the data in a disk
write transaction. Data is written to the disk subsystem in accordance with
policies set up by the controller. The policies include the amount of dirty or
clean cache lines, the number of cache lines available, elapsed time from the last
cache flush, and others.
PERC7.2_UG.book Page 173 Thursday, March 3, 2011 2:14 PM