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Reader's Voice: Building Your Own File Server

Power, Heat, And Memory

The interior of the case. It isn't pretty, with four PATA cables, seven hard drives, a DVD drive, and power connectors.

You will want to keep the internals of your new file server reasonably cool. The less heat generated, the less heat you will have to exhaust. There are more energy-efficient drives that use less power than standard drives. There are also low-power processors out there that can reduce power consumption. Both are worth considering.

I also strongly recommend that you select an efficient power supply that meets the 80 PLUS standard. There are a few 80+ Bronze (82%) and 80+ Silver (85%) efficient power supplies around that are reasonably priced. It is important to correctly size the power supply. There will be a surge of power when the hard drives are spinning up. A good hard drive controller will stagger the spin-up of the drives to minimize this. I have yet to see a controller on a northbridge and southbridge equipped with such a feature.

Both of my servers use 80% efficient power supplies. The first server has dual Pentium III 933 MHz CPUs, six 250 GB hard drives, and an operating system disk. Peak power when booting is 214 W, and the power consumption is 95 W when the CPU runs at a 100% load. The second server has dual low-voltage Xeon 2.8 GHz CPUs with six 750 GB hard drives and an operating system disk. Peak power when booting that one is 315 W, and the machine uses 164 W when idle and 260 W when the CPU is pegged at 100%.

Unless you have more than six hard drives in your array or a really hot CPU, you don't need a power supply rated at more than 400 W. Of course, the power supply will have to be able to supply enough of the different voltages that the computer will use, but getting a 750 W plus power supply will only waste money and end up running less efficiently than a 400 W power supply.

Memory

Most enthusiasts don't spend enough time talking about memory reliability. They mostly care about clock frequency and latency, which are less important in this environment than reliability. As the data goes in and out of your file server, it is stored in system memory. There are parity calculations done in memory. Data on disk is cached. The best pre-built file server boxes use error correcting code (ECC) memory, while the cheaper ones don't. In my opinion, it is silly to build a high-performance file server and not use ECC memory.

This is the Supermicro MV8 controller card, plugged into a PCI-X slot.

Memory is unlikely to have a permanent error, but is very likely to have non-permanent errors, called transient errors. IBM estimates that with 1 GB of memory, there will be a transient error every week. Alpha particles in the memory packaging and cosmic rays cause these errors. However, ECC has extra memory that is used to detect and correct memory errors. Standard-quality ECC memory will detect all 2-bit errors in 64 bits of memory and correct all 1-bit errors. There are higher-quality ECC components available, such as what IBM offers with its Chipkill memory.

Errors in areas of the memory that are written to before they are read, or unused areas in the memory are not a problem. However, a memory error that otherwise affects processing in some way is a bad thing. Serious server motherboards, such as those from Tyan and Supermicro, will log memory errors. Cheaper motherboards, such as my Asus CUR-DLS and Asus NCCH-DL, will support ECC memory, but won't log memory errors.

There are some CPU chipsets that do not support ECC memory at all, and motherboards manufactured on these chipsets will not support ECC memory. I recommend using only motherboards that support ECC memory, and using only ECC memory in them. If you are really worried about memory errors, the better motherboards will support IBM's Chipkill technology, which will detect and correct many multi-bit errors and even continue to function if a single chip fails.

See the following links for details:

ECC SDRAM Primer
IBM’s Chipkill White Paper

EETimes on IBM’s Chipkill

Soft Errors in Electronic Memory

  • wuzy
    Yet again why is this article written so unprofessionally? (by an author I've never heard of) Any given facts or numbers are just so vague! It's vague because the author has no real technical knowledge behind this article and are basing mainly on experience instead. That is not good journalism for tech sites.

    When I meant by experience, I didn't mean by self-learning. I meant developing your own ideas and not doing extensive research on every technical aspects for the specific purpose.
    Reply
  • wuzy
    And even if this is just a "Reader's Voice" I'd expect a minimum standard to be set by BoM on articles they publish to their website.
    Most IT professionals I have come to recognise in the Storage forum (including myself) can write a far higher caliber article than this.
    Reply
  • motionridr8
    FreeNAS? Runs FreeBSD. Supports RAID. Includes tons of other features that yes, you can get working in a Linux build, but these all work with just the click of a box in the sleek web interface. Features include iTunes DAAP server, SMB Shares, AFP shares, FTP, SSH, UPnP Server, Rsync, Power Daemon just to name some. Installs on a 64MB usb stick. Mine has been running 24/7 for over a year with not a single problem. Designed to work with legacy or new hardware. I cant reccommend anything else. www.freenas.org
    Reply
  • bravesirrobin
    I've been thinking on and off about building my own NAS for around a year now. While this article is a decent overview of how Jeff builds his NAS's, I also find it dancing with vagueness as I'm trying to narrow my parts search. Are you really suggesting we use PCI-X server motherboards? Why? (Besides the fact that their bandwidth is separate from normal PCI lanes.) PCI Express has that same upside, and is much more available in a common motherboard.

    You explain the basic difference between fakeRAID and "read RAID" adequately, but why should I purchase a controller card at all? Motherboards have about six SATA ports, which is enough for your rig on page five. Since your builds are dual-CPU server machines to handle parity and RAID building, am I to assume you're not using a "real RAID" card that does the XOR calculations sans CPU? (HBA = Host Bus Adapter?)

    Also, why must your RAID cards support JBOD? You seem to prefer a RAID 5/6 setup. You lost me COMPLETELY there, unless you want to JBOD your OS disk and have the rest in a RAID? In that case, can't you just plug your OS disk into a motherboard SATA port and the rest of the drives into the controller?

    And about the CPU: do I really need two of them? You advise "a slow, cheap Phenom II", yet the entire story praises a board hosting two CPUs. Do I need one or two of these Phenoms -- isn't a nice quad core better than two separate dual core chips in terms of price and heat? What if I used a real RAID card to offload the calculations? Then I could use just one dual core chip, right? Or even a nice Conroe-L or Athlon single core?

    Finally, no mention of the FreeNAS operating system? I've heard about installing that on a CF reader so I wouldn't need an extra hard drive to store the OS. Is that better/worse than using "any recent Linux" distro? I'm no Linux genius so I was hoping an OS that's tailored to hosting a NAS would help me out instead of learning how to bend a full blown Linux OS to serve my NAS needs. This article didn't really answer any of my first-build NAS questions. :(

    Thanks for the tip about ECC memory, though. I'll do some price comparisons with those modules.
    Reply
  • jimbofluffy
    "BSD Linux", whats that? I know of BSD.
    Reply
  • ionoxx
    I find tat there is really no need for dual core processors in a file server. As long as you have a raid card capable of making it's own XOR calculations for the parity, all you need is the most energy efficient processor available. My file server at home is running a single core Intel Celeron 420 and I have 5 WD7500AAKS drives plugged to a HighPoint RocketRAID 2320. I copy over my gigabit network at speeds of up to 65MB/s. Idle, my power consumption is 105W and I can't imagine load being much higher. Though i have to say, my celeron barely makes the cut. The CPU usage goes up to 70% while there are network transfers, and my switch doesn't support jumbo frames.
    Reply
  • raptor550
    Ummm... I appreciate the article but it might be more useful if it were written by someone with more practical and technical knowledge, no offense. I agree with wuzy and brave.

    Seriously, what is this talk about PCI-X and ECC? PCI-X is rare and outdated and ECC is useless and expensive. And dual CPU is not an option, remember electricity gets expensive when your talking 24x7. Get a cheap low power CPU with a full featured board and 6 HDDs and your good to go for much cheaper.

    Also your servers are embarrassing.
    Reply
  • icepick314
    Have anyone tried NAS software such as FreeNAS?

    And I'm worried about RAID 5/6 becoming obsolete because the size of hard drive is becoming so large that error correction is almost impossible to recover when one of the hard drive dies, especially 1 TB sized ones...

    I've heard RAID 10 is a must in times of 1-2 TB hard drives are becoming more frequent...

    also can you write pro vs con on the slower 1.5-2 TB eco-friendly hard drives that are becoming popular due to low power consumption and heat generation?

    Thanks for the great beginner's guide to building your own file server...
    Reply
  • icepick314
    Also what is the pro vs con in using motherboard's own RAID controller and using dedicated RAID controller card in single or multi-core processors or even multiple CPU?

    Most decent motherboards have RAID support built in but I think most are just RAID 5, 6 or JBOD....
    Reply
  • Lans
    I like the fact the topic is being brought up and discussed but I seriously think the article needs to be expanded and cover a lot more details/alternative setup.

    For a long time I had a hardware raid-5 with 4 disk (PCI-X) on dual Athlon MP 1.2 ghz with 2 GB of ECC RAM (Tyan board, forgot exactly model). With hardware raid-5, I don't think you need such powerful CPUs. If I recalled, the raid controller cost about as much as 4x pretty cheap drives (smaller drives since I was doing raid and didn't need THAT much space, it at most 50% for the life of the server, also wanted to limit cost a bit).

    Then I decided all I really needed was a Pentium 3 with just 1 large disk (less reliable but good enough for what I needed).

    For past year or so, I have not had a fileserver up but planning to rebuild a very low powered one. I was eyeing the Sheeva Plug kind of thing. Or may be even a wireless router with usb storage support (Asus has a few models like that).

    Just to show how wide this topic is... :-)
    Reply