Chapter 7 Storage

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.

Table 30

RAID 1

 

 

 

A1

 

A1

A2

 

A2

A3

 

A3

A4

 

A4

 

 

 

DISK 1

 

DISK 2

 

 

 

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.

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 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).

 

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Media Server User’s Guide