Tuesday, December 19, 2017

NAS drives

NAS drives are like cloud storage: you can access all your files from anywhere, both inside and outside of your home or office. You can use them to store and play your music and video collections, as well as documents and other files.

NAS drive buyer's guide
NAS stands for Network Attached Storage. It enables you to have a large amount of storage connected directly to your broadband router. This storage is therefore available to all your devices.

NAS drives (like DROBO B800FS ) are designed to be turned on permanently, which means you can have access to your music, movies, photos and documents at all times. Most have timers so you can set them to turn on and off during the hours you want.
One of the most popular reasons to buy an NAS drive is for media playback. Videos can be viewed on your TV, without having to connect a computer.

A NAS drive will use much less power than a regular PC, too, making it much cheaper to run. For ease of setup and ease of use, a dedicated NAS drive is hard to beat.
What capacity do I need?

The first requirement is capacity. You'll need one that has enough storage to meet your needs now and in the future. Plenty of NAS drives come with no disks at all - these are known as diskless or bare drives. The advantage is that you can choose the drives you want and how much capacity you need.

You can now get disks up to 10TB is size, though for you’ll be paying at least £400 or so for the privilege. 4TB disks are arguably the current sweet spot, at around £120.
Disks for NAS drives

When you choose your disks, look for ones that have been designed to work specifically with NAS boxes. NAS-optimised features include more secure construction providing more resistance to vibration, which makes a lot of sense for a drive that’s designed to be on the whole time. They also offer power management so they can adjust performance based on their temperature.

These drives also offer special features in firmware known by WD as TLER (Time-Limited Error Recovery) and by Samsung and Hitachi as command completion time limit (CCTL). This optimises the error correction for drives when they are installed in a RAID array (explained below) as is usually the case with NAS drives.

What is RAID?

RAID stands for redundant array of inexpensive disks. RAID can be quite complex but at a basic level you’ll want to use it primarily to provide redundancy so if a disk fails your data is still safe. Three of the most popular variants are RAID 1, 5 and 6.

Most NAS drives will offer at least two bays, which means that you can set them up as RAID 1. In this scenario the second drive is a mirror of the first, so if one drive fails completely all your data is safe on the other. You can then replace the faulty disk, and rebuild the RAID array.

RAID 5 requires at least three drives and offers parity data. That means a RAID 5 array can withstand a single drive failure without losing data or access to data. As data is ‘striped’ across three drives, reads are fast, but at the expensive of slower writes because of having to also write the parity data.

RAID 6 meanwhile requires four drives but offers both striped and dual parity, so two drives could fail and the RAID could still recover.

Whichever you choose however, don’t consider RAID to be your only backup of your data. If the box just dies, or if something catastrophic happens like a fire, you’ll still lose all your data. To mitigate this you'll want another external backup, preferably to the cloud.

Hot swap
Hot-swap capability enables you to take out or add a drive without having to power down first, which could be important if you’re running business applications off your NAS and want to maintain uptime.

Remote connectivity

Consider whether you’ll need remote access to the drive. Previously this required signing up to a third-party DNS service, but these days with most NAS drives you can just sign up for an account with the manufacturer as you set up the drive. Log into the account and they'll handle the connectivity to your box at home.

How powerful does your NAS’s processor need to be? The dedicated OSes that NAS drives run are lightweight, but a faster processor and more memory will enable features such as transcoding.

This means that any media files can be converted on the fly into a format that's playable by your TV or set-top box, so you don’t have to worry if it can't play the file as it exists on your NAS.

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