Thanks for your feedback Stéphane, really appreciated!
I don’t know Affa, it seems an old project: is it still maintained?
I like a separate command for the “raise” operation, too, like hotsync does. I’d like a clear distinction between the two main operations:
sync (runs multiple times)
raise (runs once)
Both ns6upgrade and HotSync are really complex procedures that deal with running systems. They aim to minimize services downtime. They are run in a critical situation for a sysadmin: system downtime. I think our mission is to ease the life of the sysadmin in such critical situations, with a simple and reliable tool – no matter its complexity from developer’s point of view.
I want to address specific situations that make the life difficult during the raise operation, with automation, pre-condition checks, and additional setup.
- IP duplication: during “raise” the source and destination have the same IP. Result is destination fails to set up the network
- Network card renaming: due to different kernel release, network devices have different names from 6 to 7, but also could be different due to hardware differences. Manual intervention required
- (specific to ns6upgrade): the Accounts provider may require manual AD setup during the “raise” procedure. Many forgot it!
post-backup-data event must be manually signaled at the end of the procedure. Many forgot it!
Most of the issues above affects also the Disaster recovery procedure. Maybe we can start by improving it!
About the sync phase I prefer the ns6upgrade approach over the HotSync one. The destination (aka “slave”) host has the control of everything, and no additional set up is required on the source system. The only exception is: installing a SSH key. I don’t know why HotSync runs a separate rsyncd service. I heard from @Stll0 and @alep that originally HotSync was over SSH too. I’d like to use SSH. What do you think?