3Ware 9650SE-2LPML User Manual page 278

Appendix A. Glossary
268
•
I²C-(or Inter-IC) bus
diagnostic, environmental, and power management for EMS (enclosure
management services).
• . Attach a set of disk drives with an existing configuration to
Import a unit
a controller and make the controller aware of the unit. Does not affect the
data on the drives.
• Initialize. For 3ware SATA RAID controllers, initialize means to put the
redundant data on the drives of redundant units into a known state so that
data can be recovered in the event of a disk drive failure. For RAID 1 and
10, initialization copies the data from the lower port to the higher port.
For RAID 5, 6, and 50, initialization calculates the RAID 5 parity and
writes it to disk (background initialization). This is sometimes referred to
as resynching, and does not erase user data.
initialization is done before the operating system has loaded, zeroes are
written to all of the drives in the unit. This process, done through the
3ware BIOS, does erase existing data.
This term is used in the 3ware CLI. It is usually shortened
• Logical Units.
to "units." These are block devices presented to the operating system. A
logical unit can be a one-tier, two-tier, or three-tier arrangement. JBOD,
Spare, and Single logical units are examples of one-tier units. RAID 1,
RAID 5, and RAID 6 are examples of two-tier units and as such will have
sub-units. RAID 10 and RAID 50 are examples of three-tier units and as
such will have sub-sub-units.
• JBOD. An unconfigured single drive. The acronym is derived from "just
a bunch of disks." Note that earlier versions of the 3ware RAID controller
exported JBODs to the OS. By default, this is not the case in 9000-series
controllers. However, a policy in 3BM can be set that allows JBODs to be
seen by the OS. By default, individual drives must be configured as
Single Disks in order to be made available to the OS.
• Migration. The process of changing the characteristics of a unit. The
change can be to expand the capacity of the unit (OCE), change the stripe
size of the unit, change the unit from redundant to non-redundant, change
the unit from non-redundant to redundant, and to change the unit from
one type of redundant unit to another type of redundant unit (for example
RAID 1 to RAID 5).
• Mirrored disk array (unit).
written, so that each provides a backup for the other. If one drive fails, the
data is preserved on the paired drive. Mirrored disk units include RAID 1
and RAID 10.
• NCQ (Native Command Queuing).
performance of SATA hard disks in some applications that require a lot of
random access of data, such as server-type applications. When NCQ is
enabled, the commands are reordered on the drive itself.
. A two-wire serial bus solution used as a control,
Note:
A pair of drives on which the same data is
A feature designed to improve
3ware Serial ATA RAID Controller User Guide
If foreground