Re: mySQL Clustering and HA (NDB - Emic Networks Solution - Replication) : Enterpise Use

[Gleb Paharenko]

Hi.



About stability of MySQL Cluster you can read at

  www.mysql.com/it-resources/case-studies/b2.php



> o Does the memory size limit the data we can manage? If it is a memory

> based solution it should mean that it can handle of a very limited

> number of databases/tables/rows, based on the available memory of the

> nodes.



Yes, MySQL Cluster stores data in the ndb storage engine, which is memory based.



For other questions see:

  http://dev.mysql.com/doc/mysql/en/MySQL_Cluster_Limitations_in_4.1.html



Mark Papadakis <[EMAIL PROTECTED]> wrote:

> Hello all,

> 

> After playing with the idea of  'abandoning ship' in favor of IBM DB2

> or Oracle, we deiced to stick with mySQL, due its simplicity and

> investment in time and experience we have put into it.

> 

> Our company needs a HA solution for ensuring 24x7 operation for the

> mySQL server instances. As it is, there are are two solutions

> available for the problem: Emic Networks's EAC for mySQL and MySQL's

> Cluster.

> 

> The Emic solution seems to work but is way too expensive for our

> budget (around 4k$ for each 2CPUs node). So we need to either go with

> NDB or try to get replication to work properly.

> 

> Here is a list of questions:

> o How 'stable' is MySQL cluster (NDB) ? Is it ready for enterprise

> use? Or even tested?

> 

> o Does the memory size limit the data we can manage? If it is a memory

> based solution it should mean that it can handle of a very limited

> number of databases/tables/rows, based on the available memory of the

> nodes.

> 

> o Is there some sort of tight integration planned for mySQL cluster

> and mySQL server ? Perhaps in 5.0 ?

> 

> o When is adding/removing nodes on the fly scheduled for

> implementation? Without such a feature the system would have to be

> shutdown - therefore not a complete HA solution.

> 

> o Has anyone gotten replication to work right? Perhaps Multi-Master replication?

> 

> Thank you very much in advance,

> MarkP

> 

> 



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Re: mySQL Clustering and HA (NDB - Emic Networks Solution - Replication) : Enterpise Use

[David Griffiths]

You should read this page on clusters:
http://dev.mysql.com/doc/mysql/en/MySQL_Cluster_Limitations_in_4.1.html
Replication and clustering is different technology.
Replication works great, but there are no algorithms to prevent the same 
row being updated on different servers at the same time (in other words, 
multimaster replication does not have collision detection algorithms 
like Oracle does). You can however chain servers together so that a 
server that is a slave is also the master to another server. I'd suggest 
you should buy & read High Performance MySQL by Derek Balling and Jeremy 
Zawodny. He discusses all these issues.

Last but not least, there is a big disconnect between "24x7" and "way 
too expensive for our budget". Say you get three computers replicating 
so that in the event of the failure of a single server, you still have 
two up and running. What if your power goes out for a day? Do you have a 
backup generator? Do you have multiple redundant network feeds? Do you 
have multiple hot-standby sites around the world to take over in the 
case of an earthquake/tidal wave/hurricane (even if you did, how long 
would it take for the DNS updates to percolate around the world)?

The cost of a setup goes up by orders of magnitude as you go past the 
99% availability. And remember, hardware requires someone on call or 
sitting at a desk 24 hours a day, 7 days a week to monitor the hardware, 
and change things around. When I worked for GTE, we spent over a million 
dollars on a single server that had redundant nodes (each with their own 
disks) all connected by a very fast fiber optic cable, and we needed 
several of them.

Food for thought.
David

Mark Papadakis wrote:
Hello all,
After playing with the idea of  'abandoning ship' in favor of IBM DB2
or Oracle, we deiced to stick with mySQL, due its simplicity and
investment in time and experience we have put into it.
Our company needs a HA solution for ensuring 24x7 operation for the
mySQL server instances. As it is, there are are two solutions
available for the problem: Emic Networks's EAC for mySQL and MySQL's
Cluster.
The Emic solution seems to work but is way too expensive for our
budget (around 4k$ for each 2CPUs node). So we need to either go with
NDB or try to get replication to work properly.
Here is a list of questions:
o How 'stable' is MySQL cluster (NDB) ? Is it ready for enterprise
use? Or even tested?
o Does the memory size limit the data we can manage? If it is a memory
based solution it should mean that it can handle of a very limited
number of databases/tables/rows, based on the available memory of the
nodes.
o Is there some sort of tight integration planned for mySQL cluster
and mySQL server ? Perhaps in 5.0 ?
o When is adding/removing nodes on the fly scheduled for
implementation? Without such a feature the system would have to be
shutdown - therefore not a complete HA solution.
o Has anyone gotten replication to work right? Perhaps Multi-Master replication?
Thank you very much in advance,
MarkP
 


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mySQL Clustering and HA (NDB - Emic Networks Solution - Replication) : Enterpise Use

[Mark Papadakis]

Hello all,

After playing with the idea of  'abandoning ship' in favor of IBM DB2
or Oracle, we deiced to stick with mySQL, due its simplicity and
investment in time and experience we have put into it.

Our company needs a HA solution for ensuring 24x7 operation for the
mySQL server instances. As it is, there are are two solutions
available for the problem: Emic Networks's EAC for mySQL and MySQL's
Cluster.

The Emic solution seems to work but is way too expensive for our
budget (around 4k$ for each 2CPUs node). So we need to either go with
NDB or try to get replication to work properly.

Here is a list of questions:
o How 'stable' is MySQL cluster (NDB) ? Is it ready for enterprise
use? Or even tested?

o Does the memory size limit the data we can manage? If it is a memory
based solution it should mean that it can handle of a very limited
number of databases/tables/rows, based on the available memory of the
nodes.

o Is there some sort of tight integration planned for mySQL cluster
and mySQL server ? Perhaps in 5.0 ?

o When is adding/removing nodes on the fly scheduled for
implementation? Without such a feature the system would have to be
shutdown - therefore not a complete HA solution.

o Has anyone gotten replication to work right? Perhaps Multi-Master replication?

Thank you very much in advance,
MarkP


-- 
Mark Papadakis
Head of R&D
Phaistos Networks, S.A

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