7
Figure 8 RAID 5
When a physical drive fails, data that was on the failed drive can be calculated from the remaining
parity data and user data on the other drives in the array. This recovered data is usually written to
an online spare in a process called a rebuild.
Application scenarios
RAID 5 is useful when cost, performance, and data availability are equally important.
Advantages
•
Has high read performance.
•
Data is not lost if only one physical drive fails.
•
More drive capacity is usable than with RAID 10, because parity information requires only the
storage space equivalent to one physical drive.
Disadvantages
•
Has relatively low write performance.
•
Data is lost if a second drive fails before data from the first failed drive is rebuilt.
RAID 6
As shown in
, RAID 6, like RAID 5, generates and stores parity information to protect
against data loss caused by drive failure. However, RAID 6 uses two different sets of parity data
(denoted by P
x,y
and Q
x,y
), allowing data to still be preserved if two drives fail. Each set of parity data
uses a capacity equivalent to that of one of the constituent drives.
Summary of Contents for UniServer B5700 G3
Page 35: ...19 Figure 29 Selecting the RAID volume to be deleted...
Page 116: ...56 Figure 96 Controller Configuration screen...
Page 220: ...61 Figure 109 Selecting Main Menu 2 Select Controller Management and press Enter...
Page 243: ...84 Figure 153 Confirming the operation...
Page 293: ...50 Figure 89 Clearing completion...
Page 382: ...21 Figure 27 Storage controller information...
Page 389: ...7 Figure 8 Identifying a storage controller 2...
