Storage

Solving the network storage dilemma

I've had some friends and readers ask me the same question about what to do about the problem of storage in the home and how do you make it accessible to every computer or set-top box in the house on the internal network.

I've had some friends and readers ask me the same question about what to do about the problem of storage in the home and how do you make it accessible to every computer or set-top box in the house on the internal network. Before I begin to answer that question, I'm going to layout the three basic options available to a user.


|> NAS (Network Attached Storage) appliance
|> Storage server with internal storage array
|> External box (USB, Firewire, or eSATA)

NAS appliances:



These are devices that work independently of any PC or Server and they're essentially dedicated storage server appliances that might run a variant of Linux, BSD, or eventually Windows Home Server. They're usually small low-power devices though that's increasing as their performance comes up to par and you start shoving more drives in to the unit (if the NAS permits expansion). These can be accessed over a home or office Ethernet network from any computer whether it's Windows, Unix, Linux, or a Mac.



The bad part about NAS devices is that they're typically fairly expensive and slow. Even the best of them peak out at around 30 MB/sec (240 mbps) while other 100 megabit models may only perform at 10 MB/sec. One of the fastest performing NAS devices on the market like the Thecus N5200 caps out at 31.8 MB/sec and the user interface leaves something to be desired. While that may be fast enough for nearly every application you can throw at it (even some simultaneous duties), it can be painfully slow moving large files in and out of a NAS especially if you have one of the slower 10 MB/sec models. 10 MB/sec is plenty fast to stream high-definition video (3 to 4 MB/sec required for HD video), but trying to copy multiple gigabyte files at 10 MB/sec will try your patience. Just remember that a terabyte will take 27 hours to fill at 10 MB/sec. The higher performance models cost as much a building your own server box. The Thecus 5-drive NAS for example costs more than $600 without any hard drives.



Storage server with internal storage array:



The nice thing about using an actual PC or server for a storage server is that it operates as fast as gigabit Ethernet will go. I just ran a test on my 2.5 TB 5-drive hot-swap storage server and it performed at more than 75 MB/sec which is more than double the speed of the fastest NAS appliance! The other nice thing about the server is that you can use it for multiple duties. For example, you can run Media Center on it and use it to record TV shows and watch videos off of it. The fact that you have a massive hard drive in it means it's got plenty of room to record TV shows.



You can also use the machine to host Virtual PC 2007 (free) or VMware guests (not free) which means you can host virtual servers such as a virtual Asterisk VoIP PBX or virtual IPCop firewall and even a virtual Windows Home Server. Since the server is on 24×7, you can VNC or Remote Desktop in to the machine from the outside world using a free DDNS service. This gives you a permanent home base. That means you can get triple or even quadruple duty out of a single box that might run at 70 (hard drives not spinning) to 105 watts of idle power consumption which is very reasonable. A standalone NAS with 5 hard drives in it will run between 30 (hard drives not spinning) to 65 watts which is better but it only does one thing and you may end up using more power with separate devices.


The downside of a personal server is that you have to set up a dedicated PC which can easily be large, noisy, and power hungry if it isn't built correctly. We can usually deal with the noise and power consumption issues with the right components, but the size isn't something that's easily solved especially if you want to plug in 5 or 6 hard drives. The other downside is that you have to build it or get someone else to build it for you. I'll follow up a blog with the parts list you need to build a multi-purpose server that would work as a media center and massive network file server but it will be a stripped down version of my RAID performance test bed and will cost about $600 without the drives or the TV/HDTV tuner card.



External box:



These are external boxes that connect to a PC via USB 2.0, Firewire, or eSATA (external SATA).



|> eSATA devices are the latest addition to the market and they operate as fast as internal SATA devices but it means you have to have one externally exposed eSATA port per hard drive you connect. While that gives you maximum speed that allows you to go full throttle with every hard drive, you need that many ports and cables to connect and it may be easier to attach the drive internally via hot-swap bay if you have the space in your PC chassis. eSATA comes in handy when you want an external device you can quickly attach and transfer data with. The problem is that not every PC has an eSATA port though it's fairly easy to add on to a desktop computer. The problem is that the eSATA port isn't always there while USB 2.0 is almost always there.
|> Firewire and USB 2.0 devices are similar in the way they function and perform though USB 2.0 is much more common. The problem is that the USB 2.0 port (despite its 60 MB/sec rating or 480 mbps rating) are typically capped at 30 MB/sec in real world implementation.


Devices such as the Drobo can hold 1 to 4 hard drives and it's connected via a single USB 2.0 port and your computer sees a single storage device/volume. While that's certainly nice and simple, you're putting a 30 MB/sec performance cap on four hard drives that have 60 MB/sec of performance a piece. That may not be a problem for many people and the simplicity of a box that just plugs in is appealing to most people, I'm just warning you of the performance tradeoff you're making. The Drobo promotional video also makes some pretty ambitious claims and I'm not here to tell you that it's bogus or that it's good. I haven't actually reviewed the unit but the claims in the video look a little too good to be true and those were most likely very small files that were on the unit for it to be able to recover failures so quickly. I have a real hard time believing it can actually give you redundancy if you yank a 500 GB drive filled with data when your other 2 drives in the unit are only 120 GBs a piece and that kind of funny math just doesn't compute. Then after spending roughly $700 on the bare Drobo, you still haven't bought the disks or the PC you're going to attach it to.



The other thing you need to worry about is the fact that an external storage box CANNOT function without the help of a full blown PC that is attached and always turned on if you want to access that data from the local network or Internet. That means not only are you dealing with the power and space consumption of the external storage box along with the extra cabling and power adapter, you're going to have a fully operational PC running as a server. The only difference here is that instead of having the drives internal, it's connected via a performance-crippled USB 2.0 or Firewire cable. External boxes may be convenient for shuttling large amounts of data around by foot, but it may not be the best permanent storage solution.


In conclusion, you need to figure out which of the above terabyte storage solutions fits your particular needs and weigh it against the pros and cons. Each one of the solutions are more than enough to stream high-definition video from, it's just a question of how quickly do you want to move data in and out of the unit.



Posted by George Ou

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