Papa's Got a Brand New NAS

It used to be that the true sign you were dealing with a Linux geek was the pile of computers lying around that person's house. How else could you experiment with networked servers without a mass of computers and networking equipment? If you work as a sysadmin for a large company, sometimes one of the job perks is that you get first dibs on decommissioned equipment. Through the years, I was able to amass quite a home network by combining some things I bought myself with some equipment that was too old for production. A major point of pride in my own home network was the 24U server cabinet in the garage. It had a gigabit top-of-rack managed switch, a 2U UPS at the bottom, and in the middle was a 1U HP DL-series server with a 1U eSATA disk array attached to it. Above that was a slide-out LCD and keyboard in case I ever needed to work on the server directly.

The 1U server acted as my primary server for just about everything. It was the gateway router, local mail relay and secondary MX for my personal domains, DNS server, DHCP server, and with the eSATA array, it became our home NAS (Network Attached Storage) array that we used for general file storage and backups. Everything generally worked well, and if you ignored the power bill and the space it took up, it was quite the impressive setup in its day.

The key phrase here is "in its day", because these days, a combination of virtualization and cloud computing means you are more likely to see a Linux geek with a laptop than a pile of servers. As computers have become faster, smaller and cheaper, my 1U server was starting to show its age. Given that all of my eggs were in this basket, I started wondering about what I'd do if one of the expensive components on the server failed. Although the server had been stable up to this point, I realized it wouldn't last forever, and if it did break, I could buy modern hardware for the cost of replacing, for instance, one of its fancy serial-attached SCSI drives. I ended up researching a lot of different options, and in this article, I describe how I ended up replacing that 24U cabinet and all the hardware in it with something that's smaller than a shoe box, much lower-powered and relatively cheap.

It's an ARM's World

At the beginning of my search, I started down a more traditional route with a cheap 1U server and a modern motherboard, but I quickly started narrowing down the motherboards to small, lower-power solutions given this machine was going to run all day. As I started considering some of the micro ATX solutions out there, it got me thinking: could I use a Raspberry Pi? After all, the latest iteration of the Raspberry Pi has a reasonably fast processor, a decent amount of RAM, and it's cheap, so even if one by itself wasn't enough to manage all my services, two or three might do the trick and not only be cheaper than a standard motherboard but lower power as well.

If you have been reading my column through the years, you'll know I'm no stranger to solving problems with Raspberry Pis—whether it's controlling the temperature of a beer fridge, creating a gaming media center, flashing coreboot onto an X200 or controlling my 3D printer. Unfortunately when you are talking about a home server, in particular a NAS, even recent Raspberry Pis have some limitations.

The first limitation with a Raspberry Pi isn't the CPU or the RAM, but the network card. A 10/100 network card is fast enough for some services around the house, but if you are setting up a NAS these days, those big media files demand a gigabit network, and the USB2 port on a Raspberry Pi isn't fast enough to drive a USB gigabit NIC.

The second limitation is disk I/O. Even if a Raspberry Pi had a gigabit NIC, your storage options are limited to what you can fit on a microSD card or a hard drive hanging off one of the USB2 ports, and USB2 is just too slow for a modern NAS. If a Raspberry Pi had USB3, you could bypass the network limitations with a USB3 gigabit NIC to it, but as it stands, the I/O is just too slow to replace even an old 1U server that has eSATA disks on a gigabit network.

So a Raspberry Pi was out of the race, but that got me thinking—I knew there were other cheap ARM single-board computers out there that had different hardware options. If I could find one with decent network and storage I/O, maybe it could be a contender.

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Kyle Rankin is VP of engineering operations at Final, Inc., the author of many books including Linux Hardening in Hostile Networks, DevOps Troubleshooting and The Official Ubuntu Server Book, and a columnist for Linux Journal. Follow him @kylerankin