LSI MegaRAID Express 500 - Manual (Page 144)

MegaRAID Express 500 Hardware Guide 130
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.