I'm upgrading a DSS environment and only have a single OneCick server- Is this a problem when there will be multiple SpectroSERVERs running differing versions
It would not be recommended to have only a single OneClick (OC) server running in a DSS environment that you are upgrading which during the time of the upgrade you will have SpectroSERVERs running differing versions.
If there are multiple SpectroSERVERs (SS) that you are going to have to upgrade that will be done over a period of days, running a single OC server can and has been seen to cause issue with communication / not working correctly when it is trying to communicate with SS running differing versions which is what you would have.
It would be recommended to instead install a secondary OC even if only temporarily during the upgrade so that you would have at all times a OC at the older version of Spectrum for the machines that have not been upgraded, and also a OC for the machines that have been upgraded.
You would need to modify the .hostrc files on the OC servers and SSs so that the non upgraded SS only communicate with the non upgraded, OC and the upgraded SS only were only communicating with the upgraded OC.
Once the upgrade was successfully completed if needed you could decommission the non upgraded OC (it is always recommended to have a secondary OC) and modify the .hostrc file on the SS and OC so that they are all able to communicate with each other.