CloudLab Utah c6620 downtime - August 6th

[Aleksander Maricq]

Hi all,

We are planning an all-day downtime of the c6620 machines at CloudLab Utah on August 6th from 9 AM to 6 PM MDT.  Existing experiments using the c6620 machines will not be able to be extended past August 6th at 9 AM.  None of the other hardware types at CloudLab Utah should be affected by this.

During this time, we will be moving the c6620 100Gb experiment net wires to new switches, which will allow the 100Gb interfaces on the c6620 machines to be synchronized using PTP.  This feature had been planned since the beginning of this expansion, but unforeseen limitations with our current switch prevented us from rolling this out until we got new switches.  For reasons both technical and non-technical, we want to make this move as soon as we are able to.  While we have the nodes out of service, we will also be upgrading the firmware on all of the c6620 machines to their latest available versions.

The side-effect of this change is that the c6620 100Gb interfaces will have to be split between two switches, where they were all on the same switch before.  That means that some pairs of nodes will have more switch hops between them than before, so if you want to avoid interswitch links in your experiment, you can specify this in your profile using `link.setNoInterSwitchLinks()`.

Let us know if you have any questions or concerns.

Best,

 - Aleks