5
69
RAID 0 (Striped)
RAID 0 reads and writes sectors of data interleaved among multiple drives. If any disk
member fails, it affects the entire array. The disk array data capacity is equal to the
number of drive members times the capacity of the smallest member. RAID 0 does
not support fault tolerance.
RAID 1 (Mirror)
RAID 1 writes duplicate data onto a pair of drives and reads both sets of data in
parallel. If one of the mirrored drives suffers a mechanical failure or does not respond,
the remaining drive will continue to function. Due to redundancy, the drive capacity of
the array is the capacity of the smallest drive.
RAID 5 (Parity)
RAID 5 provides data striping at the byte level and also stripes error correction
information. This results in excellent performance and good fault tolerance. Level 5 is
one of the most popular implementations of RAID.
RAID 0+1 (Striped Mirror)
RAID 10 is a combination of striping and mirroring. This configuration provides optimal
speed and reliability, but you need four SATA hard disks.
Spanning (JBOD)
JBOD stands for “Just a Bunch of Disks”. Each drive is accessed as if it were on a
standard SCSI host bus adapter. This is useful when a single drive configuration is
needed, but it offers no speed improvement or fault tolerance. A spanned volume is a
formatted partition which data is stored on more than one hard disk, yet appears as
one volume. Unlike RAID, spanned volumes have no fault-tolerance, so if any disk
fails, the data on the whole volume could be lost. Additionally, the system or boot
partitions cannot be included in a spanned volume. FAT16/32 and NTFS file systems
may be used, and the volume can span up to 32 hard disks.
Comparison Table :
Solution
Hard Disks No.
Capacity
Performance
Reliability
Application
RAID0
>=2
All
Highest
Dangerous
Look for speed
RAID1
2
50%
Read faster
Excellent
100% Data backup
RAID5
>=3
N-1
Read faster
Write slower
Good
Limited budget
RAID0+1
>=4
(Even number)
Smallest
*2
High
Excellent
Unlimited budget
Span
>=1
All
none
Dangerous
Big disk space
