List:General Discussion« Previous MessageNext Message »
From:Shawn Green Date:June 11 2012 3:39pm
Subject:Re: i need advice on redundancy of mysql server.
View as plain text  
On 6/11/2012 10:36 AM, Ananda Kumar wrote:
> ...
> Master-master allows load balancing.
>

Why do people keep replication rings as if they are the best possible 
configuration? A master-slave relationship also permits load balancing 
and is easier to maintain and recover in the event of a node failure.

Any MySQL replication topology cannot, in a generic sense, allow load 
balancing. Careful precautions must be maintained in your load balancer 
and in your application code to avoid data collisions (adding or 
modifying the same PK on the same table on two or more nodes at the same 
time).

For continuous uptime, you do need redundancy. For the 'limited 
downtime' scenario that the customer proposed, this includes 
geographical redundancy as well as physical duplication and should also 
include sharding his data so that the loss of one sharded set (due to 
extreme disaster or comms failure) does not knock all of his users 
offline at the same time.

"realtime" data is also a variable definition. For hydrologic monitoring 
data 'realtime' could mean within the last 15 minutes.  For some 
applications (such as telecommunication) 'realtime' is measured in 
microseconds.  It may be that the customer's requirements can tolerate a 
normal variance in duplication time provided by MySQL's native 
replication. If not, then rewriting (notice I did not say "porting") 
their application to use MySQL Cluster may be the way to meet their 
"realtime" requirements.

Yes, master-master replication can be useful (in an active-passive 
setup) for rapid failover and recovery if you take the appropriate 
precautions. It is not recommended for the newest administrators because 
recovery can become complicated. One should really understand basic, 
top-down master-slave replication before attempting to create a 
replication ring.

Active-Active (dual master) configuration is even more complicated and 
is suited only for specific application purposes. This is definitely an 
advanced technique and requires careful planning and engineering to 
perform properly.

Regards,
-- 
Shawn Green
MySQL Principal Technical Support Engineer
Oracle USA, Inc. - Hardware and Software, Engineered to Work Together.
Office: Blountville, TN


Thread
i need advice on redundancy of mysql server.Joey L11 Jun
  • Re: i need advice on redundancy of mysql server.Ananda Kumar11 Jun
    • Re: i need advice on redundancy of mysql server.Shawn Green11 Jun
      • Re: i need advice on redundancy of mysql server.Joey L11 Jun
        • Re: i need advice on redundancy of mysql server.Shawn Green11 Jun
          • Re: i need advice on redundancy of mysql server.Baron Schwartz11 Jun
            • Re: i need advice on redundancy of mysql server.Andrew Moore11 Jun
              • Re: i need advice on redundancy of mysql server.Baron Schwartz11 Jun
                • Re: i need advice on redundancy of mysql server.Joey L12 Jun
                  • Re: i need advice on redundancy of mysql server.Claudio Nanni12 Jun
                  • Re: i need advice on redundancy of mysql server.Johan De Meersman13 Jun
                    • Re: i need advice on redundancy of mysql server.Prabhat Kumar13 Jun
    • Re: i need advice on redundancy of mysql server.Joey L11 Jun
      • Re: i need advice on redundancy of mysql server.Andrew Moore11 Jun
        • Re: i need advice on redundancy of mysql server.Joey L11 Jun
  • RE: i need advice on redundancy of mysql server.Rick James13 Jun
    • Re: i need advice on redundancy of mysql server.Joey L14 Jun