> Hi Mircea > > I think you're missing an intro section with the use cases we want to > handle in 5.2. > > The requirements for having a backup datacenter that isn't accessed > by > any clients are pretty different from the requirements for multiple > "primary" datacenters that are all handling requests at the same > time, > so we should have a clear image of what we are trying to achieve. >
+1. That becabe very clear after reading Bela's email :-) > > On Fri, Feb 10, 2012 at 5:47 PM, Bela Ban <[email protected]> wrote: > > I'm going to comment via this mailing list, and we can later > > summarize > > and append to the wiki (I don't like discussions on the wiki... > > :-))... > > > > #1 Virtual cluster > > > > Rehashing: > > > > I believe we'll have to come up with a custom consistent hash that > > knows > > about the 2 sites, and places all of the data owners into the local > > site. E.g. it would be bad if we create a key K in LON and make the > > primary owner T (in SFO) and the backup owner B in LON ! > > This should also minimize rehashing across sites, and prefer > > rehashing > > within sites. > > > > For some use cases I would think it's essential that the data is > replicated in both sites (async, of course). > But I second the idea that there must be at least one backup in the > same site as the primary owner, or rehashes become really expensive. +1. Or rehash can be inproved to send statet only if the joiner is colocated (vs send state if node is primary owner). > > > In terms of data access, the idea is that all writes would only go > > through 1 site, e.g. LON being active and SFO being a backup (in > > which > > reads could happen); my design didn't assume concurrent writes in > > multiple sites (at least not to the same data). +1. I'll make that clearer in the doc as well. > > > > I like the idea of designating one site as the "master", but I'm > pretty sure we want to handle use cases where there is more than one > master. +1 > Perhaps we could incorporate Erik's suggestion on the wiki and allow > the selection of a master site both at a cache level and at a key > level. +1 Thanks Dan! _______________________________________________ infinispan-dev mailing list [email protected] https://lists.jboss.org/mailman/listinfo/infinispan-dev
