Question



  • Just a question to see if this is possible. Multicast over my lan is slow enough that unicast ends up being a better option. We’re talking pushing maybe 60 Mbps. I’m sure this is something to do with the config of my Cisco switches, but unless it’s a super quick fix, that’s neither here nor there.

    I’m wondering the following:

    I setup a physical fog server, replicate over the images from my master server. Import all my hosts into it as well. I plug this server into a switch, and plug all my clients into that switch. I plug the switch into the network, and update my DHCP settings to point to this new, physical fog server.

    clients boot. get to the join multi-task option on all clients. disconnect the switch from the network, effectively isolating it. join the task on all of them.

    Image hopefully goes as fast as it can.


  • Moderator

    For your switches, make sure that igmp snooping is enabled. Also remember that the slowest device in your multicast group sets the pace of the multicast stream. If you are imaging 9 i7s with nvme drives and 1 pentium 4 with a sata hdd the multicast group will operate at the speed the pentium 4 system can digest the data. Or if you have 9 machines on a 1GbE network and one machine on a 100Mb/s link, the speed of the multicast stream will be restricted to the 100Mb/s link.

    60mb/s is not a value that FOG would offer. If that is measured bandwidth speed, ok. But FOG’s partclone measures in Dataflow over a minute. So what speed does partclone say during the multicast stream.

    I might try a portion of what you proposed for a test, but instead of disconnecting that imaging switch from the rest of the network, leave it connected. The switch should keep all multicast traffic on that switch as long as there are no subscribers anywhere else the network.

    A on a healthy 1GbE network you should get about 6.1GB/m transfer rates. For a multicast on that same network you should get between 4.0-5.5GB/min. On my network I routinely get 13GB/min+ unicast image to modern hardware from a virtual machine FOG server. Just to set some expectations.


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