Thanks David.... We decided to do it at our client-side as the initial implementation. I will investigate the approaches for supporting the fine grained control of the resources consumed by a sever, tenant, and CF.
Thanks, Indika On Thu, Jan 20, 2011 at 3:20 PM, David Boxenhorn <da...@lookin2.com> wrote: > As far as I can tell, if Cassandra supports three levels of configuration > (server, keyspace, column family) we can support multi-tenancy. It is > trivial to give each tenant their own keyspace (e.g. just use the tenant's > id as the keyspace name) and let them go wild. (Any out-of-bounds behavior > on the CF level will be stopped at the keyspace and server level before > doing any damage.) > > I don't think Cassandra needs to know about end-users. From Cassandra's > point of view the tenant is the user. > > On Thu, Jan 20, 2011 at 7:00 AM, indika kumara <indika.k...@gmail.com>wrote: > >> +1 Are there JIRAs for these requirements? I would like to contribute >> from my capacity. >> >> As per my understanding, to support some muti-tenant models, it is needed >> to qualified keyspaces' names, Cfs' names, etc. with the tenant namespace >> (or id). The easiest way to do this would be to modify corresponding >> constructs transparently. I tought of a stage (optional and configurable) >> prior to authorization. Is there any better solutions? I appreciate the >> community's suggestions. >> >> Moreover, It is needed to send the tenant NS(id) with the user credentials >> (A users belongs to this tenant (org.)). For that purpose, I thought of >> using the user credentials in the AuthenticationRequest. s there any better >> solution? >> >> I would like to have a MT support at the Cassandra level which is optional >> and configurable. >> >> Thanks, >> >> Indika >> >> >> On Wed, Jan 19, 2011 at 7:40 PM, David Boxenhorn <da...@lookin2.com>wrote: >> >>> Yes, the way I see it - and it becomes even more necessary for a >>> multi-tenant configuration - there should be completely separate >>> configurations for applications and for servers. >>> >>> - Application configuration is based on data and usage characteristics of >>> your application. >>> - Server configuration is based on the specific hardware limitations of >>> the server. >>> >>> Obviously, server limitations take priority over application >>> configuration. >>> >>> Assuming that each tenant in a multi-tenant environment gets one >>> keyspace, you would also want to enforce limitations based on keyspace >>> (which correspond to parameters that the tenant payed for). >>> >>> So now we have three levels: >>> >>> 1. Server configuration (top priority) >>> 2. Keyspace configuration (payed-for service - second priority) >>> 3. Column family configuration (configuration provided by tenant - third >>> priority) >>> >>> >>> On Wed, Jan 19, 2011 at 3:15 PM, indika kumara <indika.k...@gmail.com>wrote: >>> >>>> As the actual problem is mostly related to the number of CFs in the >>>> system (may be number of the columns), I still believe that supporting >>>> exposing the Cassandra ‘as-is’ to a tenant is doable and suitable though >>>> need some fixes. That multi-tenancy model allows a tenant to use the >>>> programming model of the Cassandra ‘as-is’, enabling the seamless migration >>>> of an application that uses the Cassandra into the cloud. Moreover, In >>>> order >>>> to support different SLA requirements of different tenants, the >>>> configurability of keyspaces, cfs, etc., per tenant may be critical. >>>> However, there are trade-offs among usability, memory consumption, and >>>> performance. I believe that it is important to consider the SLA >>>> requirements >>>> of different tenants when deciding the strategies for controlling resource >>>> consumption. >>>> >>>> I like to the idea of system-wide parameters for controlling resource >>>> usage. I believe that the tenant-specific parameters are equally important. >>>> There are resources, and each tenant can claim a portion of them based on >>>> SLA. For instance, if there is a threshold on the number of columns per a >>>> node, it should be able to decide how many columns a particular tenant can >>>> have. It allows selecting a suitable Cassandra cluster for a tenant based >>>> on his or her SLA. I believe the capability to configure resource >>>> controlling parameters per keyspace would be important to support a >>>> keyspace >>>> per tenant model. Furthermore, In order to maximize the resource sharing >>>> among tenants, a threshold (on a resource) per keyspace should not be a >>>> hard >>>> limit. Rather, it should be oscillated between a hard minimum and a >>>> maximum. >>>> For example, if a particular tenant needs more resources at a given time, >>>> he >>>> or she should be possible to borrow from the others up to the maximum. The >>>> threshold is only considered when a tenant is assigned to a cluster - the >>>> remaining resources of a cluster should be equal or higher than the >>>> resource >>>> limit of the tenant. It may need to spread a single keyspace across >>>> multiple >>>> clusters; especially when there are no enough resources in a single >>>> cluster. >>>> >>>> I believe that it would be better to have a flexibility to change >>>> seamlessly multi-tenancy implementation models such as the Cassadra >>>> ‘as-is’, >>>> the keyspace per tenant model, a keyspace for all tenants, and so on. >>>> Based >>>> on what I have learnt, each model requires adding tenant id (name space) to >>>> a keyspace’s name or cf’s name or raw key, or column’s name. Would it be >>>> better to have a kind of pluggable handler that can access those resources >>>> prior to doing the actual operation so that the required changes can be >>>> done? May be prior to authorization. >>>> >>>> Thanks, >>>> >>>> Indika >>>> >>> >>> >> >
