matlik.net

Watching the paint peel

31 May 2008

NAS put on hold

As it turns out, life really is what happens when you are making other plans. Since the last time I posted, I’ve had a few things come along requiring big money… bummer. I guess I’ll have to wait a little longer before I build this machine. I suppose this isn’t all bad, as chances are the cost of these components go down over time, assuming the economy doesn’t throw a wrench into that theory.

I did get close to a finalized configuration of components with a slight change to the machine’s application. Originally, I wanted to make the Network Accessible Storage device double as the firewall and gateway for my home network to the internet. For security purposes, combining the firewall and storage isn’t recommended, as a security failure in the firewall makes for easy access to all your data. Beside that is the fact I already have a wireless Netgear router that can also serve as a gateway for a local wired network.

I currently have a 31” LCD television, a HDHomeRun (network enabled digital TV receiver), and no way to connect the two. A simple and lightweight media PC would nicely bridge this gap, and many of my NAS requirements would also apply here. With a media PC, I would finally have the convenience of TiVo style TV watching, and I could create backup copies of the kids’ videos that are at high risk of death by scratching. Of course, the sheer volume of data is a concern when dealing with multimedia, particularly video. To get the most out of my hard drive space and back-up media (CDs and DVDs), the machine would need to support efficient MPEG4 decoding at the very minimum. I have a Core2 duo workstation that could offload the conversion processing from MPEG2 to MPEG4 (or better), so I’m not too concerned with the media PC’s processor power as long has it supports hardware decoding of MPEG4. Given these thoughts, I’ve put together the following list of components:

  • JetWay J7F5M1G2E-VHE-LF CX700M VIA CX700M Mini ITX Motherboard/CPU Combo - This motherboard has integrated video capable of MPEG-2, MPEG-4, and WMV9 hardware decoding, high definition sound, gigabit Ethernet, HDMI output (not sure if this is video only or includes sound), and a 1GHz C7 processor that consumes a miniscule 9 watts of electricity. The board only supports 2 SATA 3.0 interfaces, so I would need to use the only PCI expansion slot to add support for disks 3 and 4. This board is fanless and therefore silent.
  • picoPSU-120 Power Kit - A fanless and very space efficient power supply capable of providing 120 watts of power at 12 volts. This is probably overkill for this machine, so I may consider scaling back to a 90 watt power kit, but I would have to run the numbers a bit more.
  • 1GB 240-Pin DDR2 SDRAM 533 (PC2 4200) Desktop Memory - I would order the cheapest respectable brand name memory on Newegg at the time I order. At present, this is the Kingston ValueRAM. The maximum memory supported by the motherboard is 1GB in a single memory card.
  • Scythe S-FLEX SFF21D 120mm Case Fan - A single, very quiet 120mm fan that could completely replace the air in my custom case roughly one time per second, which should be sufficient for the passively cooled components within.
  • Pioneer DVR-115DBK DVD Burner - This is an inexpensive and popular IDE drive. The motherboard supports up to 2 IDE devices, and I want to ensure the SATA connections are used for hard drives only.

I already have the hard drives and PCI to SATA 1.5 expansion card. These will need to be moved from their existing machines into the new one once it is built.

I haven’t yet decided how I want to boot the machine. Idealy, the hard drives would exist solely for storage. No applications would be installed on them at all. There is one more IDE device supported (in addition to the optical drive), so I could install another hard drive. However, I would like to avoid using another hard drive for space and power reduction. I was thinking something like a Compact Flash card installed as a non-removable IDE device (requires adapter card) or a USB flash drive wired directly to the motherboard and rigged inside the case. I suspect the compact flash card would be more performant, but it would also cost a little more.

The parts listed here aren’t super expensive. Unfortunately, this isn’t the only costs involved. To build the machine I really want, I need to build my own case from scratch. I not only need to buy the materials (not sure what I want to use yet), but I also have to purchase some tools, like a dremel. I have some rough ideas on how I would like to set-up the inside of the case. Maybe I’ll put together some pictures in the future, but until then, here is a brief description:

  • Four 3.5” hard drive bays will be located in the bottom front of the case. Instead of configuring them horizontally, I want to take advantage of the natural airflow advantage of a vertical configuration. Proper venting is needed (e.g. modder’s mesh) to allow airflow to pass directly over the hard drives. Maybe the bottom of the case could be vented for maximum intake.
  • Just above the hard drives is where the optical drive will be installed in the traditional horizontal position. This makes all the drives fit into a single brick-like unit in a dense but fairly well vented layout.
  • The motherboard will then be configured (looking at the front of the case) to the right of the drives. To do this, the drives, and therefore the optical drive’s tray, will be off-center to the left. Depending on the PCI expansion slot’s location, the case may need to be longer (move the motherboard further toward the back), taller (place card below drives), or a riser could be used to move the PCI card out of the way. Regardless, the motherboard needs to be flush with the back of the case to give access to the on-board ports, so this will require some designing finesse. Again, special care will be needed to ensure the passive cooling on the motherboard has sufficient air flow. This may require additional venting on the front of the case in front of the motherboard.
  • The 120mm fan will be located on the back of the case near the top. This would be located where a traditional ATX case would place the power supply. One benefit to using a very low profile power supply inside the case. Of course, this does require the power converter to be outside the machine, similar to a laptop. I did want to include a laptop battery inside the machine for backup power, but this was prohibitively expensive.

With this layout, I’d like to get an overall size of 20cm wide x 20cm tall x 25cm deep, or roughly 8in wide x 8in tall x 10in deep.

I hope to sometime return to this project, as I suspect this would be a good little machine that is used a lot. Until then, maybe someone else out there could use some of my thoughts to build something similar. If you do or already have, please share your experience. I would love to hear about your successes and growing pains.