ArrayMasStor K Series
ÒInstallation Instructions and Procedures.Ó
Copyright
Ó
Advanced Technology and Systems Co., Ltd., 11/2001 Rev. A
12
Trademarks and Trade names that may appear within this document are the property of their respective owners.
Since the K-Series RAID system does not support non-RAID storage configurations, a minimum
of two disk drives must be installed into the unit. The following section describes each of the RAID
levels supported by the system.
About RAID levels
RAID generally has six common levels (or defined configurations): RAID 0 ~ 5. RAID levels 0,
1, 3 and 5 are the most commonly used, while RAID levels 2 and 4 are rarely implemented.
The following sections describe in detail each of the commonly used RAID levels.
IMPORTANT
:
The K-Series RAID system only supports RAID 0, RAID 1, RAID 3, RAID 5,
RAID 3+Spare, and RAID 5 +Spare. ItÕs Auto Setup default RAID settings are
described later in the section ÒAuto RAID SetupÓ.
RAID 0
RAID 0 implements
block striping
where data is broken into logical blocks and striped across
several drives. Although called ÒRAID 0,Ó this is not a true implementation of RAID because there
is
no facility for redundancy
. In the event of a disk failure, data is lost and/or generally made
inaccessible.
In block striping, the total disk capacity is equivalent to the sum of the capacities of all the drives in
the array. This combination of drives appears to the system as a single logical Òor virtualÓ drive.
RAID 0 provides the highest performance
but offers no data redundancy or drive failure
protection
. It is typically faster than the other RAID levels because data can be simultaneously
transferred to/from multiple disks
and
because there are
no
complex or time consuming
calculations performed for error correcting hamming code and/or parity generation. Furthermore,
read and write operations to different drives can be processed in parallel.
RAID 1
RAID 1 (or
disk mirroring
) copies (or writes) the same data onto two sets of drives. By keeping
two copies of data on separate disks or arrays, data is protected against a disk failure. If, at any
time, a disk on either side fails, the remaining good disk (copy) can provide all of the data needed,
thus preventing downtime.
With disk mirroring, the total ÒusableÓ storage capacity is equivalent to half the sum of the
capacities of all drives in the array. Thus, for example, combining
four
100 GB drives would create
a single logical or ÒvirtualÓ drive with a total ÒusableÓ disk capacity of 200 GB. This combination
of drives is presented to (and appears as) a single logical drive to the system.
