LSI 3ware SAS 9750-8i Guia do Utilizador descarregar pdf (Página 318)

Glossary

306 3ware SATA+SAS RAID Controller Card Software User Guide, Version 10.0

• Import a unit. Attach a set of disk drives with an existing configuration to

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.

Note: If foreground

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.

• Logical Units. This term is used in the 3ware CLI. It is usually shortened

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. 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. This is no longer supported. Individual drives

should 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). A pair of drives on which the same data is

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). See “Queuing”

• Non-redundant units. A disk array (unit) without fault tolerance

(RAID 0 or single disk.).

•

OCE (Online Capacity Expansion). The process of increasing the size of

an existing RAID unit without having to create a new unit. See also

migration.

•

Parity. Information that the controller calculates using an exclusive OR

(XOR) algorithm and writes to the disk drives in RAID 5, RAID 6, and

1 2 ... 313 314 315 316 317 318 319 320 321 322 323 ... 341 342

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LSI 3ware SAS 9750-8i Guia do Utilizador Página 318

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