On Tue, Mar 20, 2012 at 9:53 PM, Jonathan Ellis wrote:
> It's reasonable that we can attach different levels of importance to
> these things. Taking a step back, I have two main points:
>
> 1) vnodes add enormous complexity to *many* parts of Cassandra. I'm
> skeptical of the cost:benefit ratio
On Wed, Mar 21, 2012 at 9:50 AM, Eric Evans wrote:
> On Tue, Mar 20, 2012 at 9:53 PM, Jonathan Ellis wrote:
>> It's reasonable that we can attach different levels of importance to
>> these things. Taking a step back, I have two main points:
>>
>> 1) vnodes add enormous complexity to *many* parts
I'm going to agree with Eric on this one. Twitter has wanted some sort of vnode
support for quite sometime. We even were willing to do all the work. I have
reservations about that now We have been silent due to the community and how
this is more like an exclusive Datastax project than an Apache
Hi Edward
> 1) No more raid 0. If a machine is responsible for 4 vnodes they
> should correspond to for JBOD.
So each vnode corresponds to a disk? I suppose we could have a
separate data directory per disk, but I think this should be a
separate, subsequent change.
However, do note that making t
On Wed, Mar 21, 2012 at 8:50 AM, Eric Evans wrote:
> I must admit I find this a little disheartening. The discussion has
> barely started. No one has had a chance to discuss implementation
> specifics so that the rest of us could understand *how* disruptive it
> would be (a necessary requirement
On Wed, Mar 21, 2012 at 3:24 PM, Tom Wilkie wrote:
> Hi Edward
>
>> 1) No more raid 0. If a machine is responsible for 4 vnodes they
>> should correspond to for JBOD.
>
> So each vnode corresponds to a disk? I suppose we could have a
> separate data directory per disk, but I think this should be
> 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 respons
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.
>>> 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
A friend pointed out to me privately that I came across pretty harsh
in this thread. While I stand by my technical concerns, I do want to
acknowledge that Sam's proposal here indicates a strong grasp of the
principles involved, and a deeper level of thought into the issues
than I think anyone else
On Tue, Mar 20, 2012 at 11:24 PM, Jeremiah Jordan <
jeremiah.jor...@morningstar.com> wrote:
> So taking a step back, if we want "vnodes" why can't we just give every
> node 100 tokens instead of only one? Seems to me this would have less
> impact on the rest of the code. It would just look like
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