ZyXEL NSA-220 Manual do Utilizador descarregar pdf (Página 67)

Chapter 6 Storage Screens

NSA-220 User’s Guide

RAID 0 capacity is the size of the smallest disk multiplied by the number of disks you have

configured at RAID 0 on the NSA. For example, if you have two disks of sizes 100 GB and

200 GB respectively in a RAID 0 volume, then the maximum capacity is 200 GB (2 * 100 GB,

the smallest disk size) and the remaining space (100 GB) is unused.

Typical applications for RAID 0 are non-critical data (or data that changes infrequently and is

backed up regularly) requiring high write speed such as audio, video, graphics, games and so

on.

6.4.3 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 volume with mirrored data. Data is duplicated across two disks, so if one disk

fails, there is still a copy of the data.

As RAID 1 uses mirroring and duplexing, a RAID 1 volume 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 volume, 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.

6.4.4 RAID and Data Protection

If a hard disk fails and you’re using a RAID 1 volume, then your data will still be available

(but at degraded speeds until you replace the hard disk that failed and resynchronize the

volume). However, RAID cannot protect against file corruption, virus attacks, files incorrectly

deleted or modified, or the NSA malfunctioning. Here are some suggestions for helping to

protect your data.

• Place the NSA behind a firewall and/or IDP (Intrusion Detection and Prevention) device

to protect it. Preferably it should be a hardware-based firewall with stateful packet

inspection, anti-virus, and IDP (like the ZyWALL UTM products).

• Use anti-virus software on your computer to scan files from others before saving the files

on the NSA.

Table 18 RAID 1

A1 A1

A2 A2

A3 A3

A4 A4

DISK 1 DISK 2

1 2 ... 62 63 64 65 66 67 68 69 70 71 72 ... 191 192

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