From mboxrd@z Thu Jan 1 00:00:00 1970 From: Anthony Liguori Subject: Re: [RFC] Switching store to use domain id's for keys Date: Wed, 31 Aug 2005 15:40:30 -0500 Message-ID: <431615BE.5040203@us.ibm.com> References: <4314C26E.9020408@us.ibm.com> <20050831092846.GX24659@cl.cam.ac.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20050831092846.GX24659@cl.cam.ac.uk> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Christian Limpach , Rusty Russell , xen-devel List-Id: xen-devel@lists.xenproject.org Christian Limpach wrote: >>The reasoning seems obvious to me, there's no easy way to get the UUID >>for a domain so constructing a UUID based path outside of Xend is very >>difficult. >> >> > >Hmm, it's less than 40 lines of C code to iterate over the /domain entries >and find a domain with a matching name or id. It would be convenient >to have library functions which does this... > > The linear search just makes me sad :-) There can still be a UUID key within the /domain tree. One can just as easily code up a function to resolve UUIDs to domain IDs by doing a linear search. I think the key is to optimize for the common case here. Since, today and I reckon for the foreseeable future, the management functions take domain IDs, it seems like the right thing to optimize for. >We'd like the identifier for a domain to remain the same after >relocating the domain to a different physical machine.[1] > > Yes, this is a tough thing to get right. It straight forward for migration, but what about save/restore, cloning, etc. It seems almost better to let UUIDs preservation to be a higher level management task. >If we consider changing this, I'd go for /domain/-. It >would make it easy to find the path for a domain on its home node but >it wouldn't work anymore once you move the domain to a new host. > > I'm partial to a more hierarchical model. Something like /domain/. It lets become part of an implicit path... Regards, Anthony Liguori >>Or, if we really want to use UUIDs in the node path, perhaps we can add >>UUIDs to the domain structure in the hypervisor so that we can actually >>query it through getdomaininfo? >> >> > >We've considered this but everytime we've found that the reason why >we wanted it was invalid. > >In any case, it seems reasonable to move the console entries to the >domain tree then... > > christian > >[1] this is currently broken since we create a new uuid on restore. >The issue is that device configuration is local to the host where the >domain is running and there's a short period of time where we want >device information for two hosts present at the same time. > > > >