Thecus Technology i Series - Manual (Page 6)

1.2 Terminology
The document uses the following terms:
RAID RAID is the abbreviation of “Redundant Array of Independent
D
isks”. There are different RAID levels with different degree
of the data protection, data availability, performance to host
environment.
PD The Physical Disk belongs to the member disk of one specific
volume group.
VG V olume Group. A collection of removable media. One VG
consists of a set of UDVs and owns one RAID level attribute.
UDV U
ser Data Volume. Each VG could be divided into several
UDVs. The UDVs from one VG share the same RAID level,
but may have different volume capacity.
CV C
ache Volume. i Series uses the on board memory as cache.
All RAM (except for the part which is occupied by the
controller) can be used as cache. User can divide the cache
for one UDV or sharing among all UDVs. Each UDV will be
associated with one CV for data transaction. Each CV could
be assigned different cache memory size.
LUN L ogical Unit Number. A logical unit number (LUN) is an
unique identifier used on a iSCSI connection which enables it
to differentiate among separate devices (each of which is a
logical unit).
GUI G
raphic User Interface.
RAID width,
RAID copy,
RAID row
(RAID cell in
one row)
RAID width, copy and row are used to describe one VG.
E.g.:
1. One 4-disk RAID 0 volume: RAID width= 4; RAID
copy=1; RAID row=1.
2. One 3-way mirroring volume: RAID width=1; RAID
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.
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