Dear, in order to migrate some slave server, we'd like to use your migration toolkit if it's possible. Basically we have some old nodes that should be merged into newer one. Due that we are into a master->slave environment we'd like to procede in that way: detach the salve server (that contain the services the we want migrate to another slave) from the master. Then use the migration toolkit to move the services from that server to another slave attached to the previous master. Is it possible?
No, this is not possible. The target server must not be part of the same multiserver environment. Detaching a server is not possible. You would have to use the ISPCopy tool instead.
But the ISPCopy tool is needed in order to completely make a copy of a server to another server. Right? In that case what we needs is instead merging an old slave to a new slave.
Manually. Disable cron jobs on the old slave, change the server id inside of the ISPConfig master db to the target slave (important to make sure you have NO conflicts), do a full tools->resync of all related data, rsync all webdata from the old to the new slave etc. I cannot provide you a step by step solution and you will have to make full backups of everything as this could go wrong badly.