Tuesday, September 6, 2011

Network-Attached Storage (NAS) vs. External Hard Drives: Which One is Right for You?


Sometimes, when downloading a file or installing a new program, you suddenly realize that your hard drives are full. Stricken with panic, you're forced to make a split-second decision - can I uninstall this or delete that? Here's how to get the space you need without even getting your hands dirty.

Options, options, optionsTraditionally, if you filled up your hard drive, you had two main options: delete a bunch of the old data to make room for the new, or buy a bigger hard drive, open up your computer and install it. If you have enough space, that second option works pretty well. For notebook and all-in-one users, however, that often entails trying to do a bit-by-bit copy of one drive's contents onto the other, or reinstalling an operating system on a bigger drive and starting from scratch.
Times have changed, however, and adding extra storage to your machine is now as simple as plugging in a cord. There are two main types: external hard drives plug into a data port like USB, FireWire, eSATA or Thunderbolt. Drives like these will appear as a drive letter or directory to Windows and OS X. In most respects, you can treat them as you would any other internal drive, including booting from them.
The second option has historically been reserved for professional users or advanced home users, and lives on your computer's network. A NAS device, short for network-attached storage, plugs into your router or switch and provides storage and data access to any computer that can get online at your house.
RAID arraysBoth external hard drives and NAS drives can come as single drives or multiple drives, in any number of configurations. When the storage is pooled together along certain guidelines, it's known as RAID, which stands for Redundant Array of Independent Disks. There are several levels of RAID, but we'll only cover two in this article: RAID 0 and RAID 1.
RAID 0 is something of a misnomer - it isn't redundant at all. In this scenario, your data is striped between two different drives in an alternating fashion. What this means is that you can read and write your data much faster than with a single drive - up to twice as fast, in fact, or very close to it. The downside, however, is that if either drive fails, the data on both is irrecoverably lost. RAID 0 is nice for users who just need a large data pool with no concern for longevity, or those who need faster scratch pools for memory-hungry applications such as Adobe Photoshop.
RAID 1 is the opposite of RAID 0. Instead of splitting your data between the two drives, it writes a full copy of every bit onto both drives. This way, if one drive experiences trouble, there's a second drive with a complete file record up and ready to go. As a result, RAID 1 is much slower than RAID 0, and uses twice the storage space but offers users much higher stability.
External hard drivesBefore we go too much further into external hard drives, let's get a few of the standards out of the way. We mentioned earlier that these external drives get connected to one of the expansion ports that live on the front or sides of your computer.
Many people are familiar with plugging in a flash drive or mouse into a USB port, but you can plug big hard drives in, too. If it's a small hard drive, like those found in a laptop, or an ssd, you can plug a single cord into a USB port and convey both power and data. Large drives, like the high-capacity models found inside of desktops, will need an external power source from a wall jack in addition to a cable plugged into a USB port.
USB 2.0 hard drives will max out at a theoretical 60MB/s (real-world results will never hit that level), while newer USB 3.0 drives strive for a similarly theoretical 625MB/s before overhead. FireWire 400 and 800, which are designed to reach 400 and 800Mbps, respectively, offer similar speeds to USB 2.0; these ports are generally found on Apple computers. eSATA offers all the same speed of the SATA ports inside of your computer (3Gbps or 6Gbps, depending), but provides no power - any drives plugged into one of these ports will require auxiliary power regardless of their size.
The newest data standard to hit the scene is Thunderbolt, the name used on Apple's new iMacs and Macbooks to describe Intel's Light Peak input. These plugs can reach up to 10Gbps in theoretical testing, but their limited availability means that very few storage products can actually take advantage of it.
External hard drives are a good investment when only one person or one computer needs the extra storage. An external drive is also useful for carrying around large sets of data at one time - think gigabytes and gigabytes at a time. Since Internet connections generally offer low upload speeds, a portable hard drive can often be the quickest way to move a set of files from place to place.

Network-attached storage (NAS)
NAS are the second way to easily expand your available storage; older technologies made it very difficult for the home user to put a NAS unit in place, but recent innovations make it hardly more complex than an external hard drive.
A NAS device offers a number of advantages over traditional external hard drives. There's no need to worry about which port does what - the data lives along your network and Internet connections. That can free up USB or FireWire ports on your desktop. Moreover, since the NAS is connected to your modem or router, any computer on your network can access the data. You won't be stuck shuffling the drive from computer to computer.
NAS boxes can also be physically larger than an external hard drive without being problematic. Since you can stash these devices in a closet or beneath a cabinet, having four or more hard drives stacked in one spot doesn't cause space issues on your desk. Since these drives are attached to your home network, you can also easily make them visible on the Internet. Set up an account and you'll be able to log in from any Internet connection and access your files just as if you were sitting at your desk at home. It's like a personal, more secure version of the cloud.
When it comes to speed, networked storage is something of a mixed bag. Gigabit is the current standard, which means that routers and cables and network cards mostly support 1000Mbps, or 1Gbps, data transfer. After overheard on both the network and the NAS, you might not reach the full speed of your hard drives - but it should be close. Regardless, it'll be a lot faster than USB 2.0 (USB 3.0, eSATA and Thunderbolt should all beat it).
Many users have primarily wireless networks these days, however, even on desktops. 802.11g Wi-Fi is limited to 54Mbps, or roughly 7MB/s. 802.11n can push it to 150 or 300Mbps, neither of which approach the speed and stability that wired networks offer. Accessing a NAS wirelessly is fine for small files, or streaming some kinds of content; for anything bigger, it's easiest to just jack in via your computer's Ethernet port.

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