Case Idea

Introduction

I want a computer case that doesn’t exist. I have a bunch of features I want and some existing cases have a subset of the features, but none have all of them. So I am thinking about the idea of how to create this case.

Goals

  • 19" rack mount
  • All I/O connections on the “front” of the case
  • hotplug disks on the “front” of the case
  • power connection on the “front” of the case
  • Be able to mount servers on both sides of a 4 post rack
  • Easy to remove from rack for working on
  • Retail price of $60-100 depending on features

Non-goals

  • Be a node in a high power compute cluster. There are lots of cases that already do this and are designed to hold high wattage CPUs. Max PSU wattage of 150W, normally way less.

Uses

  • high density, low-power servers in a 4-post rack
  • in a telecom rack, where connections are needed on the front and accessing the rear is difficult
  • under table, embedded in a panel, etc. Situations where you want all the connections on one side.
  • low power machine to be used as a router/proxy/server/PBX/etc in a home or small office.

Features

  • 19" 2-post telco rack mount
  • 1U in height
  • very short depth, just enough to hold the featured components
  • holds a mini-ITX board
  • Front I/O
  • space to hold a DC-to-DC power supply like the picoPSU
  • power input on “front” of case
  • 2 to 4 hotplug 2.5" SATA drives
  • will only be used for Atom CPUs or low wattage CPUs like the Intel L3426. The optional abilty to add fans to blow on the cpu heatsink would be nice.
  • Rails that attach to the rack and then the case slides in and out of them. Ball-bearing slides not needed, the case will be short and light so a simple channel will do.
  • The user should be able to pick which end of the case is the “front”. Combines with the above this probably means being able to mount the rails on both ends of the case.
  • needs to be rigid enough to support 2-post mounting, plastic might be ok if it works
  • OPTIONAL: PCI slot- not needed, but might be interesting if it can fit, possibly at the cost of another feature in some configs (like you could choose to have PCI instead of hotplug SATA
  • OPTIONAL: if the space for the DC-to-DC PSU could also hold a AC-to-DC PSU instead, that might make it more general purpose
  • OPTIONAL: tool-less lid removal if it doesn’t add much cost

Existing Cases

Model PS Wattage Drive bays Price Notes
SC502-200B 200W 2×2.5″ fixed $100 fixed disk, might need active heatsink, rear i/o and mounting brackets don’t look movable
SC503-200 200W 2×2.5″ fixed $90 fixed disk, front i/o, might need active heatsink, power is on rear (but you could take it out and hack in your own)
SC502L-200B 200W 2×2.5″ fixed $90 for Atom, no fans, fixed disk, rear I/O and mounting brackets don’t look movable
SC503L-200B 200W 2×2.5″ fixed $76 for Atom, no fans, fixed disk, front I/O, power is rear
SC510T-200B 200W 2×2.5″ hotplug $150 rear I/O and mounting brackets don’t look movable, hotplug disks on front
Casetronic C159-60W 60W 1×3.5″ fixed $240

Other similar solutions

There are a few vendors producing blade systems that use standard ATX and mini-ITX mainboards

There are several vendors that sell 1U cases that hold 2 or 4 mini-ITX boards and a varying amount of drives.

Components that might be useful

Blank Cases

  • BUD Industries has a bunch of options for empty cases a quick price search indicates $45-65 each for the aluminum ones depending on size and quantity ($22-45 for plastic)
  • Jameco carries blank cases from various suppliers
  • lots more

Rails

Drive Adapters – these might let us chose to use an existing standard feature to add hotplug drives (more flexible, but probably adds some cost).

install two 2.5" drives in a single 3.5" drive spot.

install 2.5" drives in a PCI slot

install four 2.5" drives in a 5.25" case bay

install two 2.5" drives in a 3.5" case bay

Potential Solutions

Idea: Modify an existing product to meet more of the required goals

  • Some of the Supermicro Front I/O style cases have the power on the rear. You could pull out the power supply and install a picoPSU and mount the input power jack on the front. CONS: you pay for a power supply that you don’t use, wasted space, extra effort
  • With some modifications you could remove the mounting brackets and install rails on most cases, allowing you to turn a Rear I/O into a Front I/O machine. CONS: extra effort
  • Use drive adapters to convert a 3.5", 5.25" bay, or a pci slot into sata hotplug bays to add drives to an existing case. CON: expensive, adds $25-50 case for 2-4 drives

Idea: Start with a blank case and create the needed features

  • CON: Not already setup with ATX mounting standoffs, you’d have to drill/tap/install them
  • PRO: some of the blank cases are pretty cheap
  • PRO: doesn’t waste a power supply
  • PRO: you could design the layout and not waste space
  • CON: tons of effort

Idea: Contract a case manufacturer (like Casepro.cn) to do a custom OEM design

  • PRO: exactly what we want
  • CON: probably a minimum order if you want it to be cheap
  • PRO: can be cheap in volume

Specification notes

  • mini-ITX: wikipedia page and VIA page. The Board is 17cm X 17cm, the four screw mounting holes and the locations of the backplate and expansion slot are from the ATX standard.
  • Drive Bay Sizes
Name Width (in) Depth (in) Height (in)
3.5" 4.00 5.75 1.00
5.25" 5.75 8.0 1.63

NOTE: the 5.25" drive bay standard height is lower than the 1U height of 1.75", so it might be possible to have a bay that you could install a 4 2.5" SATA drive adapter in.

  • The ATX I/O shield height is 1.89", which is taller than 1U anyway so doesn’t apply. As a result, for systems using an I/O shield the size is vendor specific, but are all roughly the same. Many vendors design the port openings right into the case, limiting your options for mixing and matching.

Other notes

  • The use of DC power isn’t just about saving space. If you just have one machine it can use a power brick, but if you have a bunch you could setup a large redundant, controllable, UPS-backed power supply to power and control them all. We need a design for this too, probably using off-the-shelf redundant power supply, ups, and arduino or something for remote control.
  • mini-box.com has a DC side UPS that could be used rather than using an consumer AC UPS.
  • Likewise in a 4-post rack situation with servers on both sides, you could have a central cooling setup with some big fans providing ventilation.