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From Mimi Aluminium <mimi.alumin...@gmail.com>
Subject Re: cluster size, several cluster on one node for multi-tenancy
Date Fri, 18 Feb 2011 09:55:23 GMT
Thanks a lot for you suggestions,
I will check the virtual keyspace solution - btw, currently I am using
Thrift client with Pycassa, I am not familiar with Hector - does it mean
we'll need to move to Hector client?

I thought of using keyspaces for each tenant, but I dont understand how to
define the whole cluster. Meaning, assuming the tenants are distributed
(replicated) across hundreds  of DCs each consists of tens of racks and
servers, so can I define a single cassandra cluster for all the servers? it
does not seem to be reasonable , this is the reason I thought of sepearating
the clusters. Please let me know how would you solve it?
Thanks,
Miriam



On Thu, Feb 17, 2011 at 10:30 PM, Nate McCall <nate@datastax.com> wrote:

> Hector's virtual keyspaces would work well for what you describe. Ed
> Anuff, who added this feature to Hector, showed me a working
> multi-tennancy based app the other day and it worked quite well.
>
> On Thu, Feb 17, 2011 at 1:44 PM, Norman Maurer <norman@apache.org> wrote:
> > Maybe you could make use of "Virtual Keyspaces".
> >
> > See this wiki for the idea:
> > https://github.com/rantav/hector/wiki/Virtual-Keyspaces
> >
> > Bye,
> > Norman
> >
> > 2011/2/17 Frank LoVecchio <frank@isidorey.com>:
> >> Why not just create some sort of ACL on the client side and use one
> >> Keyspace?  It's a lot less management.
> >>
> >> On Thu, Feb 17, 2011 at 12:34 PM, Mimi Aluminium <
> mimi.aluminium@gmail.com>
> >> wrote:
> >>>
> >>> Hi,
> >>> I really need your help in this matter.
> >>> I will try to simplify my problem and ask specific questions
> >>>
> >>> I am thinking of solving the multi-tenancy problem by providing a
> separate
> >>> cluster per each tenant. Does it sound reasonable?
> >>> I can end-up with one node belongs to several clusters.
> >>> Does Cassandra support several clusters per node? Does it mean several
> >>> Cassandra daemons on each node? Do you recommend doing that ? what is
> the
> >>> overhead? is there any link that explain how to do that?
> >>>
> >>> Thanks a lot,
> >>> Mimi
> >>>
> >>>
> >>> On Wed, Feb 16, 2011 at 6:43 PM, Mimi Aluminium <
> mimi.aluminium@gmail.com>
> >>> wrote:
> >>>>
> >>>> Hi,
> >>>> We are interested in a multi-tenancy environment, that may consist of
> up
> >>>> to hundreds of data centers. The current design requires cross rack
> and
> >>>> cross DC replication. Specifically, the per-tenant CFs will be
> replicated 6
> >>>> times: in three racks,  with 2 copies inside a rack, the racks will
be
> >>>> located in at least two different DCs. In the future other replication
> >>>> policies will be considered. The application will decide where (which
> racks
> >>>> and DC)  to place each tenant's replicas.  and it might be that one
> rack can
> >>>> hold more than one tenant.
> >>>>
> >>>> Separating each tenant in a different keyspace, as was suggested
> >>>> in  previous mail thread in this subject, seems to be a good approach
> >>>> (assuming the memtable problem will be solved somehow).
> >>>> But then we had concern with regard to the cluster size.
> >>>> and here are my questions:
> >>>> 1) Given the above, should I define one Cassandra cluster that hold
> all
> >>>> the DCs? sounds not reasonable  given hundreds DCs tens of servers in
> each
> >>>> DC etc. Where is the bottleneck here? keep-alive messages, the gossip,
> >>>> request routing? what is the largest number of servers a cluster can
> bear?
> >>>> 2) Now assuming that I can create the per-tenant  keyspace only for
>  the
> >>>> servers that in the three racks where the replicas are held,  does
> such
> >>>> definition reduces the messaging transfer among the other servers.
> Does
> >>>> Cassandra optimizes the message transfer in such case?
> >>>> 3) Additional possible solution was to create a separate clusters per
> >>>> each tenant. But it can cause a situation where one server has to run
> two or
> >>>> more Cassandra's clusters. Can we run more than one cluster in
> parallel,
> >>>> does it means two cassandra daemons / instances on one server? what
> will be
> >>>> the overhead? do you have a link that explains how to deal with it?
> >>>>
> >>>> Please can you help me to decide which of these solution can work or
> you
> >>>> are welcome to suggest something else.
> >>>> Thanks a lot,
> >>>> Mimi
> >>>>
> >>>>
> >>>>
> >>>>
> >>>>
> >>>>
> >>>>
> >>
> >>
> >>
> >> --
> >> Frank LoVecchio
> >> Senior Software Engineer | Isidorey, LLC
> >> Google Voice +1.720.295.9179
> >> isidorey.com | facebook.com/franklovecchio | franklovecchio.com
> >>
> >
>

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