Glossary, Continued

Spare

A hard drive available to back up the data of other drives.

Stripe Size

The amount of data contiguously written to each disk. You can specify stripe sizes of 4

 

KB, 8 KB, 16 KB, 32 KB, 64 KB, and 128 KB for each logical drive. For best

 

performance, choose a stripe size equal to or smaller than the block size used by the host

 

computer.

Stripe Width

The number of disk drives across which the data are striped.

Striping

Segmentation of logically sequential data, such as a single file, so that segments can be

 

written to multiple physical devices in a round-robin fashion. This technique is useful if

 

the processor can read or write data faster than a single disk can supply or accept it.

 

While data is being transferred from the first disk, the second disk can locate the next

 

segment. Data striping is used in some modern databases and in certain RAID devices.

Terminator

A resistor connected to a signal wire in a bus or network for impedance matching to

 

prevent reflections, e.g., a 50 ohm resistor connected across the end of an Ethernet cable.

 

SCSI chains and some LocalTalk wiring schemes also require terminators.

Ultra-SCSI

An extension of SCSI-2 that doubles the transfer speed of Fast-SCSI, providing 20 MBs

 

on an 8-bit connection and 40 MBs on a 16-bit connection.

Ultra2-SCSI

An extension of SCSI-2 that doubles the transfer speed of Ultra-SCSI, providing 40 MBs

 

on an 8-bit connection and 80 MBs on a 16-bit connection.

Ultra3-SCSI or 160M An extension of SCSI-2 that doubles the transfer speed of Ultra2-SCSI, providing 80MBs on an 8-bit connection and 160 MBs on a 16-bit connection.

Virtual Sizing FlexRAID Virtual Sizing is used to create a logical drive up to 80 GB. A maximum of eight logical drives can be configured on a RAID controller and RAID migration is possible for all logical drives except the eighth. Because it is not possible to do migration on the last logical drive, the maximum space available for RAID migration is 560 GB.

Wide SCSI A variant on the SCSI-2 interface. Wide SCSI uses a 16-bit bus, double the width of the original SCSI-1. Wide SCSI devices cannot be connected to a SCSI-1 bus. Wide SCSI supports transfer rates up to 20 MB/s, like Fast SCSI.

130MegaRAID Express 500 Hardware Guide