incubator-cassandra-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Vijay <vijay2...@gmail.com>
Subject Re: RFC: Cassandra Virtual Nodes
Date Thu, 22 Mar 2012 02:26:58 GMT
>>> I envision vnodes as Cassandra master being a shared cache,memtables,
and manager for what we today consider a Cassandra  instance.

It might be kind of problematic when you are moving the nodes you want the
data associated with the node to move too, otherwise it will be a pain to
cleanup after that (Something like nt clean). I think a vnode should be as
much isolated as possible to reduce the impact when it is moving (which
will become a normal cluster operation), Just my 2 cents.

Regards,
</VJ>



On Wed, Mar 21, 2012 at 5:41 PM, Edward Capriolo <edlinuxguru@gmail.com>wrote:

> I just see vnodes as a way to make the problem smaller and by making the
> problem smaller the overall system is more agile. Aka rather then 1 node
> streaming 100 gb the 4 nodes stream 25gb. Moves by hand are not so bad
> because the take 1/4th the time.
>
> The most simple vnode implementation is vmware.  Just make sure that 3 vm
> nodes consecutive nodes so not end up on the same host. This is wasteful
> because we have 4 jvms.
>
> I envision vnodes as Cassandra master being a shared cache,memtables, and
> manager for what we today consider a Cassandra  instance. Makes it simple
> to think about.
>
> On Wednesday, March 21, 2012, Peter Schuller <peter.schuller@infidyne.com>
> wrote:
> >> Software wise it is the same deal. Each node streams off only disk 4
> >> to the new node.
> >
> > I think an implication on software is that if you want to make
> > specific selections of partitions to move, you are effectively
> > incompatible with deterministically generating the mapping of
> > partition to responsible node. I.e., it probably means the vnode
> > information must be kept as state. It is probably difficult to
> > reconcile with balancing solutions like consistent hashing/crush/etc.
> >
> > --
> > / Peter Schuller (@scode, http://worldmodscode.wordpress.com)
> >
>

Mime
  • Unnamed multipart/alternative (inline, None, 0 bytes)
View raw message