05-17-2013, 08:11 PM
Kuci pretty much said it all.
It's difficult to calculate what percentage of speed loss you will see because it depends on a number of factors (number of nodes, number of GPUs, network topology, attack mode, number of hashes, etc), but the biggest problems you will experience with ethernet are very slow starts and erratic performance.
It may take several minutes for hashcat to actually start cracking, and then when it does, your speeds will be all over the place. You might have one or two GPUs cracking at full speed, a few more cracking at half speed, and then you'll probably have several that are barely doing any work at all.
But used Infiniband hardware is no more expensive than ethernet hardware. You can find SDR switches for just a couple hundred bucks, and HCAs for under $50. If you can afford to buy lots of GPUs for a cluster, you can surely afford to build an appropriate network for the cluster. Even if you have to sacrifice buying one or two GPUs to build a solid network, it's well worth it.
It's difficult to calculate what percentage of speed loss you will see because it depends on a number of factors (number of nodes, number of GPUs, network topology, attack mode, number of hashes, etc), but the biggest problems you will experience with ethernet are very slow starts and erratic performance.
It may take several minutes for hashcat to actually start cracking, and then when it does, your speeds will be all over the place. You might have one or two GPUs cracking at full speed, a few more cracking at half speed, and then you'll probably have several that are barely doing any work at all.
But used Infiniband hardware is no more expensive than ethernet hardware. You can find SDR switches for just a couple hundred bucks, and HCAs for under $50. If you can afford to buy lots of GPUs for a cluster, you can surely afford to build an appropriate network for the cluster. Even if you have to sacrifice buying one or two GPUs to build a solid network, it's well worth it.