Raid 0; Raid 1; Table 39 Raid 1; Table 40 Raid 10 - ZyXEL Communications NSA-2401 User Manual

6.9.4 RAID 1

RAID 1 creates an exact copy (or mirror) of a set of data on another disk. This is useful when
data backup is more important than data capacity. The following figure shows two disks in a
single RAID 1 array with mirrored data. Data is duplicated across two disks, so if one disk
fails, there is still a copy of the data.

Table 39 RAID 1

A1
A2
A3
A4
DISK 1
As RAID 1 uses mirroring and duplexing, a RAID 1 array needs an even number of disks (two
or four for the NSA).
RAID 1 capacity is limited to the size of the smallest disk in the RAID array. For example, if
you have two disks of sizes 150 GB and 200 GB respectively in one RAID 1 array, then the
maximum capacity is 150 GB and the remaining space (50 GB) is unused.
Typical applications for RAID 1 are those requiring high fault tolerance without need of large
amounts of storage capacity or top performance, for example, accounting and financial data,
small database systems, and enterprise servers.
6.9.5 RAID 10
RAID 10 (RAID 1+0) is a nested RAID where two RAID 1 arrays are stored on the physical
disks with a RAID 0 array on top. It is a stripe of mirrors. RAID 1 provides redundancy while
RAID 0 boosts performance. The following figure shows two disks in two RAID 1 arrays.
Data is duplicated across two disks, so if one disk fails, there is still a a copy of the data. These
two arrays are configured as a single RAID 0 array for faster performance

Table 40 RAID 10

A1
A3
A5
A7
DISK 1
NSA-2401 User's Guide
A1
A2
A3
A4
DISK 2

RAID 0

RAID 1
A1 A2
A3 A4
A5 A6
A7 A8
DISK 2 DISK 3
Chapter 6 Storage Screens
RAID 1
A2
A4
A6
A8
DISK 4
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