Jail hot migration

Andrew Hotlab andrew.hotlab at hotmail.com
Fri Sep 10 12:48:45 UTC 2010

> Date: Fri, 10 Sep 2010 16:28:15 +1200
> From: freebsd at snap.net.nz
> To: freebsd-jail at freebsd.org
> Subject: Jail hot migration
> Hi guys,
> I was lately thinking around jail hot-migration feature where one jail
> could be moved from one host to another without
> shutting it down, something like vmotion in VMware world.
> The storage layer should be easy with zfs send and receive or some form
> of shared storage. The tricky part would
> be a memory copy from one node to another and also the CPU handling.
> Anyone has an idea how this could be achieved? I guess it would require
> a kernel module which could take care of memory
> reservations and a daemon to copy and incrementally sync the jails
> memory across.
> Then also there is the CPU problem..
> Sounds like a fair amount of work and development.
> All comments are welcomed!
Well, I'm not a developer, but I think that the jail framework surely deservestobe evolved in something more "friendly" from a sysadmin's point of view.
The architecture is great, and that's just enough to consolidate a lot of workloads,but for some applications there are features (resource containers, offline andonline migration of jails, etc.) that need to be improved to be affordable in aproduction environment.
I think that a lot of work is getting done (resource container and virtualizationstack projects have ben just sponsored by the FreeBSD Foundation), I do not knowhow much time will take to reach a complete "business-ready" virtualizationframework, neither if they are on the right path, but I'm quite confident, because I'msure that the simplicity of the FreeBSD solution will rule any other virtualizationframework out there.
As the feature you are asking for, I think that resource containers and offlinemigration should be considered first, because overall they'll have more impact onbusiness environments. Further, I believe that building a hot migration procedureworking with third-party running applications will be a very complex task to achieve,maybe too expensive at this time, compared to the amount of work required.
That's an interesting argument, I'll be glad if more member of the Community willcontribute with their considerations.


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