Terminology - Thecus i Series User Manual

1.2 Terminology

The document uses the following terms:
RAID is the abbreviation of "Redundant Array of Independent
RAID
Disks". There are different RAID levels with different degree
of the data protection, data availability, performance to host
environment.
The Physical Disk belongs to the member disk of one specific
PD
volume group.
Volume Group. A collection of removable media. One VG
VG
consists of a set of UDVs and owns one RAID level attribute.
User Data Volume. Each VG could be divided into several
UDV
UDVs. The UDVs from one VG share the same RAID level,
but may have different volume capacity.
Cache Volume. i Series uses the on board memory as cache.
CV
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.
Logical Unit Number. A logical unit number (LUN) is an
LUN
unique identifier used on a iSCSI connection which enables it
to differentiate among separate devices (each of which is a
logical unit).
GUI Graphic User Interface.
RAID width, copy and row are used to describe one VG.
RAID width,
RAID copy,
E.g.:
RAID row
1. One 4-disk RAID 0 volume: RAID width= 4; RAID
(RAID cell in
one row)
2. One 3-way mirroring volume: RAID width=1; RAID
3. One RAID 10 volume over 3 4-disk RAID 1 volume:
copy=1; RAID row=1.
copy=3; RAID row=1.
RAID width=1; RAID copy=4; RAID row=3.
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