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Re: [swift] how to configure NWR policy

 

Mike,

Thanks for you clarification. I'm interested in how to enable the following
combinations.
for case 1,  can we do it without sending the HTTP head 'X-Newest'?
for case 2,  how to enable it?
   N=3, W=2, R=2 (Strong Consistence Mode)
   N=3, W=3, R=1 (Strict Consistence Mode)

Best Regards,

                                                                             
 Edward Zhang(张华)                                                          
                                                                             
                                                                             
                                                                             
                                                                             
                                                                             
                                                                             
                                                                             
                                                                             





                                                                           
             Michael Barton                                                
             <mike-launchpad@w                                             
             eirdlooking.com>                                           To 
             Sent by:                  Hua ZZ Zhang/China/IBM@IBMCN,       
             palrich@xxxxxxxxx                                          cc 
                                       Alex Yang <alex890714@xxxxxxxxx>,   
                                       "openstack@xxxxxxxxxxxxxxxxxxx"     
             12/11/2012 02:31          <openstack@xxxxxxxxxxxxxxxxxxx>,    
             PM                        Hai HJ Ji/China/IBM@IBMCN           
                                                                   Subject 
                                       Re: [Openstack] [swift] how to      
                                       configure NWR policy                
                                                                           
                                                                           
                                                                           
                                                                           
                                                                           
                                                                           




Does any of our documentation say NRW are directly configurable?  It's not
really quite that simple.

N is a property of the cluster, chosen when you build the ring.
W is always a simple majority of N.
R is generally 1 (eventually consisten reads), but the client can request
it be bumped to N (> highly consistent reads) using X-Newest.

But then there's stuff like we provide RYW consistency on default reads,
which can't really be modeled by NRW notation.

- Mike



On Mon, Dec 10, 2012 at 9:47 PM, Hua ZZ Zhang <zhuadl@xxxxxxxxxx> wrote:
  Alex, that make sense to me.  thanks a lot. :-)

  Best Regards,

                                                                             
       Edward Zhang(张华)                                                    
                                                                             
                                                                             
                                                                             
                                                                             
                                                                             



  Alex Yang ---12/11/2012 11:37:24 AM---Alex Yang <alex890714@xxxxxxxxx>
                                                                           
       Alex Yang <                                                         
       alex890714@gmail.                                                   
       com>                                                                
                                                                           
                                                                        To 
       12/11/2012 11:37                                                    
       AM                              Hua ZZ Zhang/China/IBM@IBMCN,       
                                                                           
                                                                        cc 
                                                                           
                                       "openstack@xxxxxxxxxxxxxxxxxxx" <   
                                       openstack@xxxxxxxxxxxxxxxxxxx>, Hai 
                                       HJ Ji/China/IBM@IBMCN               
                                                                           
                                                                   Subject 
                                                                           
                                       Re: [Openstack] [swift] how to      
                                       configure NWR policy                
                                                                           
                                                                           
                                                                           
                                                                           
                                                                           
                                                                           



  Hi, Zhang,
  Just add 'X-Newest: Ture' in the HTTP GET request.


  2012/12/11 Hua ZZ Zhang <zhuadl@xxxxxxxxxx>
        Hi all,

        I have a question about swift configuration for NWR policy.
        According to some documents of Swift, NWR is configurable. The
        general configuration is: N=3, W=2, R=1 or 2.
        Swift can provide both models of consistency: strong and eventual.
        But I can't find where to configure this option.

        Any suggestion is appreciated!

        Best Regards,

                                                                             
       Edward Zhang(张华)                                                    
       IBM China Software Development                                        
       Lab                                                                   
                                                                             
                                                                             
                                                                             
                                                                             
                                                                             



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