How important is dual-gigabit lan for a super user's home NAS?

Question

Long story short: I'm building my own home server based on Ubuntu with 4 drives in RAID 10. Its primary purpose will be NAS and backup.

Would I be making a terrible mistake by building a NAS Server with a single Gigabit NIC?

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Long story long: I know the absolute max I can get out of a single Gigabit port is 125MB/s, and I want this NAS to be able to handle up to 6 computers accessing files simultaneously, with up to two of them streaming video.

With Ubuntu NIC-bonding and the performance of RAID 10, I can theoretically double my throughput and achieve 250MB/s (ok, not really, but it would be faster). The drives have an average read throughput of 83.87MB/s according to Tom's Hardware.

The unit itself will be based on the Chenbro ES34069-BK-180 case. With my current hardware choices, it'll have this motherboard with a Core i3 CPU and 8GB of RAM. Overkill, I know, but this server will be doing other things as well (like transcoding video).

Unfortunately, the only Mini-ITX boards I can find with dual-gigabit and 6 SATA ports are Intel Atom-based, and I need more processing power than an Atom has to offer.

I would love to find a board with 6 SATA ports and two Gigabit LAN ports that supports a Core i3 CPU. So far, my search has come up empty. Thus, my dilemma.

Should I hold out for such a board, go with an Atom-based solution, or stick with my current single-gigabit configuration?

I know there are consumer NAS units with just one gigabit interface (probably most of them), but I think I will demand a lot more from my server than the average home user.

Any advice is appreciated. Thanks.

Solution

Your configuration is unlikely to require dual-GbE, especially if you're using 5.4K RPM drives like the chart suggests you are. You will see maximum throughput when fetching large, sequentially stored (unfragmented) files. Unless you're taking steps to maintain sequentiality of your files, perhaps by using XFS, GigE speeds are unlikely in this config. Random I/O, which is more likely, won't even come close to GigE speeds which is why nearly all Home/SOHO NAS heads come with a single GigE port.

You say you want two NICs so you can support two GigE-speed copies going at the same time. If two clients are copying at the same time, the drives will need to serve data from two different parts of the drives. The I/O access pattern will be 'random' in that case, and the aggregate speed seen by both clients, even in a NIC-bonding scenario, will not be anywhere close to GigE. You don't have anywhere near the drive-count for that.

You don't need two NICs, so go with the Mini-ITX motherboard that supports the CPU you need.

Comments

[Andrew Ensley]

This is exactly the kind of advice I was looking for. I hadn't started my research on File Systems yet, but now it sounds like I want XFS :-). Even with XFS, though, it sounds like it might not be worth worrying about dual NICs. Would you agree?

[SysAdmin1138]

Absolutely. Even with 7.2K RPM drives, you won't risk crossing the GigE threshold until you get more than 12ish actively serving data. Dual NICs is an extra you can do without.

[Andrew Ensley]

Great. Thank you for putting my mind at ease!