1.3 Terminology

The document uses the following terms:

RAID

RAID is the abbreviation of “Redundant Array of Independent

 

Disks. There are different RAID levels with different degree of the

 

data protection, data availability, and performance to host

 

environment.

 

 

PD

The Physical Disk belongs to the member disk of one specific RAID

 

group.

 

 

RG

Raid Group. A collection of removable media. One RG consists of a

 

set of VDs and owns one RAID level attribute.

 

 

VD

Virtual Disk. Each RD could be divided into several VDs. The VDs

 

from one RG have the same RAID level, but may have different

 

volume capacity.

 

 

CV

Cache Volume. Controller uses onboard memory as cache. All RAM

 

(except for the part which is occupied by the controller) can be used

 

as cache.

 

 

LUN

Logical Unit Number. A logical unit number (LUN) is a unique

 

identifier which enables it to differentiate among separate devices

 

(each one is a logical unit).

 

 

GUI

Graphic User Interface.

 

 

RAID

RAID width, copy and row are used to describe one RG.

width,

E.g.:

RAID

1. One 4-disk RAID 0 volume: RAID width= 4; RAID copy=1;

copy,

RAID row

RAID row=1.

(RAID cell

2. One 3-way mirroring volume: RAID width=1; RAID

in one row)

copy=3; RAID row=1.

 

 

3. One RAID 10 volume over 3 4-disk RAID 1 volume: RAID

 

width=1; RAID copy=4; RAID row=3.

 

 

WT

Write-Through cache-write policy. A caching technique in which the

 

completion of a write request is not signaled until data is safely

 

stored in non-volatile media. Each data is synchronized in both data

 

cache and accessed physical disks.

 

 

WB

Write-Back cache-write policy. A caching technique in which the

 

completion of a write request is signaled as soon as the data is in

 

cache and actual writing to non-volatile media occurs at a later time.

 

It speeds up system write performance but needs to bear the risk

 

where data may be inconsistent between data cache and the

 

physical disks in one short time interval.

 

 

RO

Set the volume to be Read-Only.

 

 

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APC iSCSI SATA II installation and configuration manual Terminology, Width, Copy, RAID row