Dell 6 series, User Manual

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Glossary
I
Initialization
The process of writing zeros to the data fields of a virtual disk and, in fault
tolerant RAID levels, generating the corresponding parity to put the virtual disk
in a Ready state. Initializing erases previous data and generates parity so that the
virtual disk passes a consistency check. Virtual disks can work without
initializing, but they can fail a consistency check because the parity fields have
not been generated.
Inter-IC
Inter-IC, also known as I
2
C, is a multi-master bus, meaning that more than one
chip can be connected to the same bus. Each chip can act as a master and
initiate a data transfer.
L
Load-balancing
Load balancing is a method of spreading work between two or more systems,
network links, CPUs, physical disk drives, or other resources. Load balancing is
used to maximize resource use, throughput, or response time. In the PERC 6
controllers, the balancing service is performed by the firmware.
You can choose between a single path for load balancing, and a “round-robin”
load balancing scheme. In single path, the firmware can detect multiple paths to
a device, and use only a single path for I/O activity to that device. The secondary
path is used if a failure is detected on the primary path.
In a simple round-robin scheme, if load balancing is enabled for the controller,
the firmware implements a round-robin scheme to issue I/Os to the redundant
path device. The round-robin scheme issues one I/O down one path, and the
other I/O down the second path, and so on. There is no restriction on firmware
regarding which path to choose first. If load balancing is disabled, the firmware
can use any one of the available paths to issue I/Os, and it should continue to
use the same path for all further I/O activity. On reboot or path failure, the
firmware again chooses any available path.
Dell_PERC6.2_UG.book Page 144 Wednesday, June 24, 2009 6:08 PM