Hello,
As far i can understand by your post, you need a high availability mysql
cluster with large capacity.
For having high availability you need something that can give you
multi-master replication between two or more mysql servers.
In my knowledge there are three solutions that can give you multi-master
replication:
1. "Official" mysql cluster
It's an Enterprise class solution, very complicated, but 'it fully
multi-master. I was using one for about two year, but i dont recommend
it because (at least in my setup) it did not have very good performance.
It's use it's own storage engine(NDB) which has a number of limitations.
2. Tungsten replicator.
It 's relative new product. It support multi-master replication between
different type of databases, and it seems very promising. It's java
based. I haven't tested it but you can read a lot about on:
http://datacharmer.blogspot.com
3. Percona xtraDB cluster
It's also a relative new product. It's also support multi-master
replication, and it seems to have very good performance. The last 3
weeks i have installed a 3 node cluster of percona software and i'm
testing it. It seems to works ok, and after some optimization it has
better performance than my production mysql setup(simple primary-slave
replication) on same hardware (virtual machines). If i dont find any
serious problem till September i will use it for production.
Now,for you application to communicate with the two mysql master nodes
there several solutions:
1. Desing your app to use both mysql servers. With this solution you can
ever split writes in the one server, and reads in the other. It's up to
you to do whatever you want.
2. Setup a simple heartbeat solution and setup a floating virtual ip
between you mysql servers. If one of the mysql server( i mean the whole
OS) crash, the floating ip will be attached to the second server.
3. In each app server, install a tcp load balancer software like
"haproxy" and balance the mysql tcp connections between your app servers
and the mysql servers.
Regards,
akops
On 18/7/2012 6:11 μμ, Carl Kabbe wrote:
We are actually facing both capacity and availability issues at the same time.
Our current primary server is a Dell T410 (single processor, 32 GB memory) with
a Dell T310 (single processor, 16GB memory) as backup. Normally, the backup
server is running as a slave to the primary server and we manually switch it
over when the primary server fails (which it did last Saturday morning at
2:00AM.) The switch over process takes 10-15 minutes although I am reducing
that to about five minutes with some scripting (the changeover is a little more
complex than you might think because we have a middle piece, also MySQL, that
we use to determine where the real data is.) Until six months ago, the time
delay was not a problem because the customer processes could tolerate such a
delay. However, we now have a couple of water parks using our system at their
gate, in their gift shops and in their concessions so we need to now move the
changeover time to a short enough period that they really don't notice. Hence,
the need I have described as 'high availability'.
The T410 is normally reasonably capable of processing our transactions, i.e.,
the customers are comfortable with the latency. However, we have been on the
T310 since last Saturday and it is awful, basically barely able to keep up and
producing unacceptable latency. Further, our load will double in the next six
months and double again the the following six months.
So, my thought was that since we have to deal with the issue change over time
which will cause us to restructure the servers, that we should also deal with
the capacity issue. I think a couple of Dell T620's will provide the capacity
we need (the servers we have spec'ed should be around 8X faster than the T410)
but I have no experience evaluating or setting up HA systems (I have worked
with MySQL for 12 years and am reasonably comfortable with it and I have read
everything I can find about HA options and their implementations.) Hence, my
post asking for help (which we are willing to pay for.)
The web app is primarily JSP's for the administration side and Flash for the
operators and other people doing transactions. The server side code is about
1.25 million lines of code and there are about 750 JSP's. The data is 950
tables with heavy use of foreign key constraints. The container is Tomcat
which runs on separate servers (the data servers only run MySQL.)
Any ideas or help in any way are always welcome.
Thanks,
Carl
On Jul 18, 2012, at 9:42 AM, Shawn Green wrote:
On 7/17/2012 8:22 PM, Carl Kabbe wrote:
On Monday, I asked if there were consultants out there who could help set up an
NDB high availability system. As I compared our needs to NDB, it became
obvious that NDB was not the answer and more obvious that simply adding high
availability processes to our existing Innodb system was.
So, I am back asking if there are consultants lurking on this list that could
help with this project.
As has been discussed on this list many times before, there are many ways to
measure 'high availability'. Most of them deal with what kind of disaster you
want to survive or return to service from. If all you are looking for is
additional production capacity then the terms you may want to investigate are
'scale out', 'partitioning', and 'replication'. All high-availability solutions
require at least some level of hardware redundancy. Sometimes they require
multiple layers in multiple locations.
Several of those features of MySQL also help with meeting some
high-availability goals.
Are you willing to discuss your specific desired availability thresholds in
public?
--
Shawn Green
MySQL Principal Technical Support Engineer
Oracle USA, Inc. - Hardware and Software, Engineered to Work Together.
Office: Blountville, TN
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