The Problem Is Choice: Building a NAS

With my external hard drives slowly and unexpectedly dying off, it is high time to dust off my plans for a dedicated storage solution. Let’s start of with my requirements.

Requirements

What I need

  1. Two to three terabytes should do just fine.
  2. The data I want to store consists of a number of file collections
    • A personal photo and video collection, currently weighing in at about 60GB.
    • A music collection of about the same size.
    • A video library consisting of a few dozen movies and full series (SD/HD), acquired digitally or ripped for convenience. (allow growth up to 1Tb)
    • Time Machine backups for 3 Macs and some kind of backup for a Windows PC. (Capped at 500Gb)
  3. Ability to survive hard disk failure, without rebuilding from a static backup.
  4. A backup solution for personal data on the storage solution that I cannot recover from their original location. (i.e. RAID is not backup)
  5. Performant enough to stream HD video and manipulate a photo library over a gigabit network.
  6. Power Efficiency. The storage service will need to be highly available. A the same time I do not want a raging power bill. So, low Power, sleep/standby capabilities are required.
  7. Direct network access, from a range of machines, simultaneously.

What I like

  1. Some kind of web-based administration center to simplify setup of the most basic services.
  2. Command-line / shell interaction for more advanced features or configuration.

What I do not need

  1. No hosting: ie. no web server / database / dns / mail / … capabilities

Solution

To me, these requirements pretty much narrow it down to a NAS setup. An independent, dedicated storage unit, reachable over wifi/wired network. So I went ahead and started looking into building a NAS myself, from commodity hardware components, or alternatively, buying a NAS box.

A NAS Box

I looked at a lot of retail boxes that provide NAS capabilities. My search started a few years back when I stumbled onto Drobo’s products. At the time, I never really considered buying one, because of their premium price. Turns out they are pretty flexible storage units, simple to manage, support different sized disks, and are easily upgradeable. But because of that they are dead slow. So Drobo is a no-no.

Two other products that stood out were Synology and QNAP. Both support about the same feature set in terms of services they export (AFP, Samba, iSCSI, …), RAID capabilities 1, Web-based Management. If I had to choose between them, I would pick the QNAP for a number of minor reasons.

  1. I fear Synology’s web-based management console is too heavy on the eye-candy (“multitasking, windowed UI”) for its 256–512MB of RAM memory 2. Every megabyte used in vain is a megabyte less that can be used for things like caching.
  2. I preferred QNAP’s design on the 4 disk models because it has hot-pluggable disk trays on the front of the device.

On the other hand, I came across some reviews that claimed particular Synology NAS boxes had a slight performance benefit over competitor systems with respect to write throughput.

Ultimately I selected the QNAP TS-419P+. Lets see how it fares with respect to the requirements I put forward:

  1. With 4 disk slots and a RAID1 or RAID10 layout this allows me to grow the storage space with time. Since 2TB disk are available at a very decent price, I can start out with 2TB (RAID1), and grow this array to 4TB (RAID10) 3.
  2. QNAP supports AFP, SMB, Time Machine volumes and Rsync. This should allow me to access my files and backup from all of my machines.
  3. With RAID1 it is protected against the failure of a single disk4.
  4. It comes with several USB and eSata ports to attach external disks for on-site backup of NAS data. It supports selected backup to external storage.
  5. It seems to do ok in performance tests I found on the web.
  6. Around 35-40Watts when in use or strained and it supports powering down the harddisks.
  7. Yes.

My biggest concern with this solution is disk compatibility. QNAP (and Synology for that matter) generally advice against consumer-grade hard disks because of issues when used in RAID, and the dreaded Load Cycle Count problem with certain WD green disks 5. Given that most reports of these issues are more than a year old, and WD has recently released new green drives (xxEARX series), I’m hoping most of these issues have been ironed out.

The official specification sheet describes these drives as consumer-NAS-ready:

Applications:
  • Desktop PCs, high capacity external storage, and NAS.
  • Desktop / Consumer RAID Environments – WD Caviar Green Hard Drives are tested and recommended for use in consumer-type RAID applications (RAID-0 / RAID-1).
The best price I could find (in Belgium) for the QNAP and two 2TB disks (table below):

DIY NAS setup

This solution is much more flexible and cheaper than the QNAP (see table below). The reason I would go with AMD Fusion is power usage and price. I have considered Atom boards, but they aren’t any cheaper, and they’re growing more obsolete by the day (No USB3, Few SATA ports, etc.). Although, the biggest issue with doing-it-yourself is setting up the software.

There is the possible incompatibility with the AMD Fusion architecture. User reports indicate issues with a recent Linux kernel will probably be minor, maybe even limited to GPU support. FreeBSD and Solaris, however, do not seem to fare so well in supporting brand new hardware.

The reason I am mentioning FreeBSD and Solaris is because I have been considering using ZFS for some time now. RAID nor ext4 have integrity checking, and RAID does have a number of documented disadvantages6, including long rebuild times.

I’ve selected a number of components to build a NAS from scratch (see table below).

conclusion

I’m a bit torn up about the decision. A NAS Box is easy to set up, and it will save me a lot of time. On the other hand, it’s less powerful and less flexible than a generic, though low-power, machine.

What’s your opinion? Do you have any comments on the QNAP box I selected? Any experience with AMD Fusion? Or should I abandon my plans and just replace my old external hard drives with new ones? Leave a comment.


  1. ignoring Synolgy’s hybrid RAID support
  2. Although I haven’t found any real numbers on memory usage to back this up.
  3. With a maximum of 6TB if I switch to 3TB disks
  4. RAID10 allows two disks to fail, given they’re not within the same mirror couple
  5. Although these seem to have been patched by WD
  6. http://en.wikipedia.org/wiki/RAID#Problems_with_RAID