Monday, December 3, 2012

Multiple GPU rigs - Open Air or Closed Chassis?


As many who have wondered down this road of using a hash rig to  crack passwords can confirm, it can be a tedious and time-consuming excersize.

Along with that, you need to build a frame for your hash rig, and make sure all connections, wires and cards are stable and properly in tact. For example, if your cat decides to use your rig as an "obstacle course" you can expect to run into some trouble..

I will re-iterate a previous comparison I did between an open-air hash rig and using a closed built PC chassis. 

Open-Air Rig (cards hang off a frame)
Pros
  • Runs much cooler, lots of air-flow.
  • Easier to get to the cards to manage connections etc.
  • More cards on a motherboard using PCI-e risers (Extenders)
  • Shape can be adjusted to your needs depending on how well you can build.
Cons
  • Attracts more dust than a vacuum cleaner in a dust storm.
  • Needs cleaning often due to the point above.
  • Everything is exposed, meaning your pet,child etc. can bump it, land on it, spill on it, throw something at it or pull on it etc etc.
  • Needs a DC for optimal dust control.
  • Not easy to build unless you're good at making metal frames.
Close-Rig( a PC Chassis etc)
Pros
  • More dust control with filters and targetted fans.
  • Protection of all the devices from any physical contact.
  • Looks neater and is quieter.
Cons
  • Heats up enough to fry eggs on the chassis.
  • Needs to be very well built with strategic fans to ensure even minimal cooling.
  • Failed intake/exhaust fans could mean the end of your system from heat failures.
  • Limited cards in one machine, and no viable alternative for network distribution. At least not reliably anyway.

And THIS is where the tables have turned. With VirtualCL not only can you now have multiple Closed-Rigs, but you dont need to squash all the cards into it either. VirtualCL allows you to create GPU Clusters, which appear as a single unit to a VCL-enabled software. This allows you for example to have 3 Machines, with 3 GPU's and a single "control node". That Control Node doesnt even need GPU's but with the proper VCL configuration it will see all the GPU's in the 3 machines.

As with anything, there are some pro's and cons. I've listed them below;

Pros
  • Can use close-rigs with GPU's to cluster as many as you want. 
  • Everything controlled from 1 system.
  • Apps like Hashcat work very well on the platform. 
  • Ideal for DC's or homes as the closed-rig machines look neat and can be stacked, packed or whatever you want to do with them. (while ensuring proper cooling of course)
Cons
  • No automated installer, needs you to know your away around the Linux command-line.
  • No Windows support (This line could have been left blank but anyway...)
  • RAM-intensive. You need to have enough RAM.
  • Very Very Very Network intensive - minimum requirement is Gigabit Ethernet, but something like Infiniband is more along the lines of what it needs. 
  • Some possible memory leaks in certain setups and configurations.
VirtualCL is obviously the way to go. Its not only for Closed-Rig machines, you could connect open-air machines to a high-speed network and use VirtualCL too. The possibilities are almost endless.

I'll be posing more about my VCL experiences as i go along.

For now, if you want to try it out, here's an excellent howto to get your started : Atom and Epixoip's VCL howto

Dimitri