64 CTERA C-Series User Guide
Linear Concatenation (JBOD)
In JBOD (“Just a Bunch Of Disks”), disks are simply concatenated, so
that they act as one large virtual disk. For example, if you have one
500 GB disk and one 250 GB disk in such an array would act as a 750
GB disk.
JBOD provides no data redundancy. If any of the drives in the array
fails, the array becomes unreadable. The advantage of JBOD is that
you can mix disks of different sizes, without losing capacity.
In RAID0, data is distributed across multiple disks, in a method called
striping. Data is written in small, set amounts to each disk in turn, thus
increasing speed with no loss of capacity.
Like JBOD, RAID0 provides no redundancy. If one disk fails, the partial
data on the other disks will become useless.
The size of the array is be the size of the smallest disk in the array,
times the amount of drives in the array.
RAID0 requires a minimum of two hard drives.
In RAID1, data is duplicated across all disks in the array, so that there
is full redundancy.
If a disk fails, the array's performance will be reduced (the array will
be marked as “Degraded”), but data will not be lost, so long as there is
at least one good disk. Data will only be lost if all the disks in the array
fail.
Since the exact same data must be written on each disk in the array,
the array's capacity is limited to that of the smallest disk.
RAID1 requires a minimum of two hard drives.
RAID5 (Striping with
distributed parity)
RAID5 requires three or more disks, and combines striping with
distributed parity to protect against data loss. If a disk fails, the array's
performance will be reduced (the array will be marked as
“Degraded”), but data will not be lost. If two disks fail, data will be
lost.
The array capacity is: (n-1)*s
Where n = number of drives, and s = size of smallest disk.
RAID5 requires a minimum of three hard drives.
To Next Page
Loading...
