Addonics Technologies ADSA4R5 User Manual

Addonics Technologies Users Guide v1.0 
4-Port SATA II PCI RAID5/JBOD Controller Card 

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RAID - Redundant Array of Independent Disks 
RAID technology manages multiple disk drives to enhance I/O performance 
and provide redundancy in order to withstan d the failure of any 
individual member, without loss of data. This card provides two RAID Set 
types, Striped (RAID 0) and Mirrored (RAID 1). 

 
2.1 Disk Striping (RAID 0) 

Striping is a performance-oriented, non-redundant data mapping technique. 
While Striping is discussed as a RAID Set type, it is actually does not provide 
fault tolerance. With modern SATA bus mastering t echnology, multiple 
I/O operations can be done in parallel, enhancing performance. Striping 
arrays use multiple disks to form a larger virtual disk. 

 

Disk mirroring creates an identical twin for a selected disk by having the data 
simultaneously written to two disks. This redundancy provides instantaneous 
protection from a single disk failure. If a read failure occurs on one drive, the 
system reads the data from the other drive. 
 

A Mirrored-Striping Set does just what it says, combining both Striping and 
Mirroring technologies to provide both the performance enhancements that 
come from Striping and the data availability and integrity that comes 
from Mirroring. When data is written to a Mirrored-Striped Set, instead of 
creating just one virtual disk, as Striping would do, a second, mirrored virtual 
disk is created as well. 
 

 
Spare Drive is a standby drive assigned to serve a Raid 1 Set. When a 
member drive of this Raid 1 set drive fails, the Spare Drive becomes a 
member drive and automatically starts to rebuild. Thus making it th e new 
member of the Raid 1Set.