User Manual

Chapter 8 Storage Manager
Cloud Storage User’s Guide
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exam ple, JBOD could convert 100 GB, 200 GB, 250 GB, and 500 GB drives int o one large logical
drive of 1050 GB. Since data isn’t striped across disks, if one disk fails, you should j ust lose t he
dat a on t hat disk (but you m ay lose dat a in t he whole array depending on t he nat ure of t he disk
failure) . You can add disks to t he JBOD array later ( using t he Add disk to JBOD feat ure) and even
rem ove them so JBOD offers a lot of flexibility. However JBOD read perform ance is not as good as
RAI D as only one disk can be read at a t im e and t hey m ust be read sequent ially. The following
figure show s t hree disks in a single JBOD array. Data is not writt en across disks but written
sequent ially to each disk unt il it ’s full.
RAID 0
RAI D 0 spreads dat a across t wo or m ore disks ( dat a striping) with no m irroring nor parit y for data
redundancy, so if one disk fails t he ent ire array w ill be lost. The m aj or benefit of RAI D 0 is
perform ance. The following figure shows t wo disks in a single RAI D 0 array. Data can be writ ten and
read across disks sim ult aneously for fast er perform ance.
RAI D 0 capacit y is t he size of the sum of the capacities of t he disks in t he RAI D 0. For exam ple, if
you have four disks of sizes 1 TB, 2 TB, 3 TB and 2 TB respectively in one RAI D 0 array, t hen t he
m axim um capacit y is 8 TB.
Typical applicat ions for RAI D 0 are non- critical dat a ( or dat a that changes infrequent ly and is
backed up regularly) requiring high write speed such as audio, video, graphics, gam es and so on.
RAID 1
RAI D 1 creat es an exact copy ( or m irror) of a set of dat a on another disk. This is useful when dat a
backup is m ore im port ant t han data capacity. The following figure shows two disks in a single RAI D
Table 31 JBOD
A1 B1 C1
A2 B2 C2
A3 B3 C3
A4 B4 C4
DISK 1 DISK 2 DISK 3
Table 32 RAI D 0
A1 A2
A3 A4
A5 A6
A7 A8
DISK 1 DISK 2