In the setup jobs window below, can I schedule a package to be delivered to my agents via the "deliver at" schedule time and then have it actually install at a later time specified by the "Activate at" time? Does it matter if my agents are using NOS or NOS-LESS Internal delivery method? How does this scheduling work, with DTS enabled agents?
The "Deliver at" and "activate at" are actually Scalability Server (SS) parameters.
When you specify a "Deliver At" and specify a time like '3PM' and an "Activate At" time at let's say '10PM', the package will get temporarily staged to the Scalability Servers at 3PM. Under the covers, all file transfers between Domain Managers (DM) and Scalability Servers (SS) are handled via 'NOS-Less DTS' and not via 'NOS' or 'NOS-Less' as agents do by default.
Later, at 10 PM, the SS sends a trigger to the agents that it has jobs ready for them. The Agent then determines if it is to be a 'NOS', 'NOS-Less' or 'NOS-Less DTS' internal deployment. If it's a NOS deployment (Default), the agent will connect to the scalability servers library share and run the install.
If NOS-Less Internal then the package will be transferred from the SS down to a temp location on the agent and then the install will be run from that temp location.
If the agent is NOS-LESS DTS (DTS agent must be installed and transfer method changed to use it) then since the package is not formally staged to the Scalability Server first, DTS will automatically go to the DM directly for it where it will then be pulled down to the same agent temp location at the deliver time. The package will be installed later (10 pm) from there at the activation time specified. This is because DTS asks the SS whether the package is in its library and for DTS purposes, a 'temporary stage' which is to a different internal location, doesn't qualify and DTS's coded behavior is to go to the DM source in that case.
If you have a package that is already staged at the SS, then the 'Deliver At' time will be ignored. If the agent being triggered is running DTS, then the agent will connect to the Scalability Server to retrieve the package since it is already staged.
If you do not have the package staged already, but selects the 'Store Packages in the Scalability Server's Staging Library' option in the job properties (Job Option sub tab), then the 'Deliver At' time will be respected AND any DTS agent will retrieve the package from the SS and not need to go to the DM directly.