American Megatrends MegaRAID Express 500 - Manual (Page 114)

MegaRAID Express 500 Hardware Guide 100
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
20MBs on an 8-bit connection and 40MBs on a 16-bit connection.
Ultra2-SCSI An extension of SCSI-2 that doubles the transfer speed of Ultra-SCSI, providing
40MBs on an 8-bit connection and 80MBs 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 160MBs 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.