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List:       linux-ha
Subject:    Re: [Linux-HA] Re: Recommended MySQL Setup
From:       "Tony's Linux" <linux () oaktechnologies ! com ! au>
Date:       2006-10-26 4:50:30
Message-ID: 200610261450.30986.linux () oaktechnologies ! com ! au
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hi daniel,

i did not realise there is a free version of SQL Server.  Just out of 
curiosity, has anyone done a HA + DRBD + SQL Server on  a linux platform as 
SQL server, being microsoft will not have a linux version ?


On Thursday 26 October 2006 13:42, Daniel Pittman wrote:
> "Rafe Slattery" <Rafe.Slattery@iquate.com> writes:
> > I'm in a similar situation and am looking for a bit of advice.  I need
> > to set up an Active-Active cluster. I have two machines to work with.
> > I was planning on using HA/drbd to cover the Apache portion of things.
> >
> > But I also need these machines to run a MySQL Cluster.
>
> When you say "active/active" do you mean that you need MySQL running on
> two machines?
>
> If so my advice would be to invest in a real database engine that
> supports master/master operation.  That will significantly reduce your
> overheads compared to trying to convince MySQL[1] to do the same.
>
> > I am investigating whether to use HA with MySQL replication
> > (Master/Slave) or go all out on a proper nbdb setup.  The DB will be
> > multiple GB in size if that's pertinant.
>
> Well, with MySQL 5.0 an NDB cluster keeps the entire database content in
> memory, so you will either be purchasing a lot of RAM or using a
> different engine.
>
> If you didn't know that ahead of time you will probably also find the
> other limitations of the NDB engine something of a surprise, and I would
> encourage you to investigate them closely before committing to anything.
>
> > I am working my way through the mysql stuff online atm but any
> > pointers / real world experience would be appreciated.
>
> Sure.  In my real world experience one-way MySQL replication with or
> without automatic promotion of the slave works great, and allows
> read-only load balancing.
>
> Two-way MySQL replication is not worth the pain and suffering you, and
> your data, will have with it.
>
> In ideal circumstances we have had problems with this, and once you
> introduce something like an unclean restart into the system it all goes
> to hell.
>
>
> I would strongly advise that you use a single MySQL database on shared
> storage -- DRBD, or shared SCSI RAID, combined with read-only
> replication to spread performance if you really, really need it.
>
> Once you start to grow your application to the point that a single
> database server becomes a choke-point you have two effective choices:
>
> You can retarget your application to a serious for-money database server
> which supports multi-master operation.  This costs, but not nearly as
> much as trying to build a multi-master system yourself.
>
> You can vertically or horizontally segregate your data and use multiple
> servers to handle the segments.  This involves application changes,
> obviously, but they are likely to be less costly than trying to get a
> multi-master system running with any low cost database engine.
>
>
> I would, personally, lean to the second option, but you know your
> application and budget better than I do.
>
> Regards,
>         Daniel
>
>
> Footnotes:
> [1]  ...or PostgreSQL, or the free versions of SQL Server, DB2 or
>      Oracle, before anyone assumes I just hate MySQL.
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