Which server actually runs the SSIS package when SQL Agent and SSISDB are on 2 different servers We have a SQL Server where we deployed the SSIS packages to its Integration Service Catalog (SSIS DB).
And we have another SQL Server where we scheduled SQL Agent to run those SSIS packages.
My question, where does the SSIS package execution actually happens? The SQL Agent server, or the Integration Service Catalog?
A little background of why we are doing/asking this: we have an old SQL Server where we deployed a lot of legacy SSIS packages. Now we have a new SQL Server where we plan to move to, but we don't want to move those legacy SSIS packages. So we are trying to just move some SQL Agent jobs to the new server to call those legacy SSIS. With some research, we thought the execution happens on the SQL Agent server, but the log says it's on the SSIS DB server. However, the execution failed and complain missing ZappySys component, which looks like the execution happened on the SQL Agent server, because we indeed don't have ZappySys component on the SQL Agent server. We are so confused now......
SSIS packages deployed to  to its Integration Service Catalog (SSIS DB) will run on the server where SSIS service and SSISDB in installed.