NAS can be used to keep common family files such as photos, music, and video in one place, accessible by everyone, as well as a secure place to backup all the family computers. It can also be used as a music/video server with a client device at the display device.
NAS is a data network attached dedicated file server accessible by any computer (and many media clients) attached to the same network. Configuration and control is by web browser communicating with a web server in the NAS. The OS, disk management, and file server software are embedded so the device operates as a network appliance. Turn it on and it’s up and running in a few seconds.
NAS units are commonly configured with 2 to 4 SATA drives, usually 500G each, but newer units can be configured with 1TB drives (for a total of 4 TB of storage). Some NAS software allows mixing drive sizes. The total storage available to the network depends on how the drives are configured and used by the NAS OS, usually in a RAID configuration (see below). Connection to the NAS from computers on the network is done through the computer OS as though the drive was attached as an external storage device.
NAS devices will typically perform diagnostics on the drives and log any drive failures. They can even be configured to send an email whenever they detect a problem such as excessive drive errors, drive failure, fan failure and over temperature conditions.
NAS boxes come in two form factors: desktop and rack-mount. This is an important consideration when designing the network. The basic rack-mount versions (4 drives) are 1RU high and 12-15″ deep. They can be noisy due to at least 4 small but high speed fans–something to consider when deciding where to install them. Desktop units are also designed to hold 4-6 drives, typically stacked vertically. They also contain fan (s), but due to better air circulation, are usually less noisy.
Learning about NAS means learning something about RAID (Redundant Array of Independent Disks). This is a technology built into the NAS box firmware that allows the simultaneous use of two or more separate drives to achieve greater levels of I/O performance and/or reliability by combining the disk storage space in different logical ways. When several physical disks are setup to use RAID technology, they are said to be in a RAID array. This array distributes data across several disks, but the array is seen by the networked computer user as a single disk. Different RAID configurations are used for different purposes, the most common referred to as RAID 0,1,5. There are also many proprietary RAID configurations such as ones offered by Drobo and Netgear that allow HD’s of different sizes and manufacturers to be mixed.
RAID 0, aka striped, means that data to be written to the NAS is divided between the disks, and written or read simultaneously. This gives a theoretical ‘n’ times read/write performance improvement (where n is the number of drives in the array). RAID 0 drives are popular with video editing applications where fast data bandwidths are needed. Any disk failure destroys the array, which becomes more likely with more disks in the array. Backup must be performed on separate drives. Given the increased performance of drives now-a-days, RAID 0 is only necessary for the most bandwidth intensive applications. The home, even for media serving, isn’t one of them.
RAID 1, aka mirroring, means that data is written simultaneously to at least two drives so that data is always duplicated. This provides an automatic backup of the data, but halves the total storage capacity of the array. For example in a 4 drive NAS, each drive with 500G, the actual capacity is 1TB with a 1TB backup. The obvious advantage of RAID 1 is excellent protection. Any drive can fail without loosing any data. In most cases, the failed drive can be “hot swapped” and the NAS software will rebuild the data on the replacement drive in the background with no loss of performance during the rebuild. The array continues to operate if at least one drive is working. This is a good solution for the home if the NAS is used for computer backups and important file storage. There is no worry about having to do additional backups.
RAID 5, aka striped disks with parity, is a kind of a combination of RAID 0 and 1. It combines three or more disks in a way that protects data against the loss of any one disk; The data is striped to at least 2 disks and parity info about the data is written to the third disk. If any one drive fails, the data from the other two drives can be used to recreate the data on the failed drive. The failed drive can usually be “hot swapped” with a new one.
Actual read/write performance of NAS boxes depends on many factors including the performance of the drives, the built-in OS software, and how much caching memory is in the box (the more the better). You can expect between 150 to 500 Mbps (about the upper limit of gigabit Ethernet). The most important spec is the read (or streaming) speed. Most manufacturers don’t publish these numbers because there dependent on the installed drives. You’ll either need to look for reviews online where speed was tested, or do the test yourself.
What to Look For
Whenever possible, as I always say in my home network classes, buy SMB (small/ medium business) or “enterprise” network equipment for the home. You want maximum reliability. In my opinion, consumer grade network equipment is just not reliable enough for custom installation.
A NAS device must be platform (OS) independent to support all platforms the customer is likely to use. This includes more than just computers. Media client devices usually make an assumption about the OS file system it can connect with. Even if the client has all PC’s, you don’t want to have to replace it if the daughter brings a Mac laptop home. Make sure the box supports:
CIFS/SMB for Windows AFP for Mac NFS for Linux and Unix
It should also be browser independent. But be careful. Some manufacturers claim support for multiple operating systems, but in fact have “minor detail” incompatibilities. A Buffalo desktop NAS I recently purchased, claimed support for Windows and Mac file systems (they didn’t say which ones!) but used a FAT32 internal file format. If it encountered a file name with more than 32 characters during a backup, it would just quit. No error message, no nothing. Moral to the story: do the homework and try it out in the office under most situations likely to be encountered at the customers. Especially make sure it will operate with any intended audio/video client. It must, of course, have a Gigabit Ethernet connection.
NAS boxes are getting popular so there are a lot of em out there. It’s tempting to go for inexpensive models. Don’t. You get what you pay for and SMB models are worth it. That said, there are some excellent “prosumer”, home-office options. For a desktop NAS, check out the Netgear ReadyNAS NV+. It will hold up to 4 SATA drives at 1TB each. The companies X-RAID software allows expansion from 1 to 4 drives with mixed storage sizes.
Another interesting desktop unit is the DroboShare from Data Robotics (shown at left with its front “door” off). The box (sold without drives) will accept any number (1-4) of drives in any storage capacity combination. A proprietary RAID technology (BeyondRAID) figures out the most efficient storage combination that still provides data protection in a RAID 5 like configuration. The customer can simply add drives of any size, one at a time, as the need for extra storage increases. The unique feature is that the Drobo OS utilizes the total capacity of each drive, unlike most RAID arrays that are limited to the size per drive of the smallest drive. The built in Linux OS accepts 3rd party aps to add all sorts of functionality to the box.
A good choice in a SMB rack-mount NAS is the Netgear ReadyNAS-1100. Their proprietary X- RAID configuration software allows expansion from 2- 4 SATA drives with mixed storage sizes for each drive and the ability to hot-swap any drive. This box is fully capable of supporting multiple HD video streams if configured correctly. The power supply and processor board are also field swappable. Netgear NAS products come with a 5-year warranty.
Another good option is the higher end desktop and rack-mount drives from Thecus. A long- time maker of very high performance NAS with a good reputation, Thecus makes SMB and enterprise NAS in many different capacities. When you feel the need for ultra-high performance, their N8800 should handle the needs of a home video production studio.
NAS As A Media Server
The only difference between NAS and a dedicated media server, especially one designed for video, is the GUI built into the server and/or the company’s client devices. The performance of a properly configured SMB NAS is certainly adequate to handle 5-6 simultaneous HD video streams. This works out to about 20 Mbps (per HD stream) X 6 streams X 1.2 overhead factor = about 150 Mbps. You have to remember that the performance of the NAS is limited to the performance of the drives. To get optimum performance for serving multiple video streams, I recommend that all drives be the same capacity and at least 7200 RPM. Note that this definitely requires a gigabit (1000BT)Ethernet connection and a gigabit capable switch. Things you should be installing anyway.
To use a NAS as a video server, you need something as a video client at the display to provide a GUI to browse and select the video files. If the customer wants to view a movie on his computer/laptop, the computer OS is the UI. To make media serving easier, many NAS OS’s support Microsoft’s UPnP AV and Apple iTunes Server.
Examples of typical media clients include an AppleTV, something like Netgear’s EVA8000, or a MCE computer. These devices provide an on-screen UI for browsing and selecting the media on the NAS but lack a lot of the fancy features of dedicated media servers.
Installation and Network Support
I would recommend setting up one NAS for the home office use and as a backup for all the computers in the home. This device should be set up as RAID1 so it’s fully protected (or equivalent protection if you use the manufacturers proprietary RAID). 1-2 TB should be more than adequate. If you’re going to use a NAS as a media server, then use a separate device for that application. It can be configured as RAID 0 for better performance although that’s probably not necessary. If a worse case scenario does occur (lose of multiple drives simultaneously), at least the media is available on the original SD or HD DVD (at least it’s supposed to be).
The NAS should be connected directly to the network switch on a gigabit port. That’s really all that’s necessary. Netgear NAS boxes offer redundant Ethernet ports to keep the drive online if one of the ports (at the switch or NAS) should fail.
Configuration is very manufacturer specific, but will include establishing a RAID configuration, setting up folders or shares, password protection, etc. I would always set up the NAS with a static IP address. Most boxes provide FTP support, which can be used for outside access to files when the customer is on the road (make sure the router ports 20, 21 are open, but a good idea to change these ports for increased security if the NAS software allows it). You might want to configure email notifications to your office when an error is detected, but at least to the customer.
One of the biggest advantages of a NAS device is it’s application as a common backup device for all the home computers. Most NAS devices are supplied with backup software for both Windows and Mac hardware (usually with 5 or more licenses). It’s a simple matter to set up a backup schedule on each PC to the NAS. If the NAS is configured as RAID 1, everyone sleeps easy.
The days of the spinning platter as a storage device are definitely numbered. We just don’t know for sure how many numbers. 2009 will be the year when solid state “drives” begin to make a real dent. They’re already offered as an higher priced option on many laptops. By 2010 they’ll still be more expensive, but much more prevalent. By 2012 they’ll be ubiquitous. Given that most hard drives used on a daily basis have about a 3-5 year life-span, The NAS you buy today will probably be your last. The next upgrade will be online solid-state storage (NASS) with reliability so good, protection schemes (backups) won’t be necessary.
If you have any questions about anything in this TIP or NAS in general, drop me an email
at firstname.lastname@example.org I will actually answer it!
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