ZyXEL Communications 4.6 User Manual

 Chapter 7 Storage

Media Server User’s Guide

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.

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 hardware-based firewall. It should have stateful packet inspection, IDP 

(Intrusion Detection and Prevention), and anti-virus (like ZyXEL’s ZyWALL UTM products for 
example).

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

NSA.

• Keep another copy of important files (preferably in another location).

RAID 1