Re: 4 Queries about DB clustering

From: Geoff N. Hiten (SRDBA_at_Careerbuilder.com)
Date: 02/11/05 

Date: Fri, 11 Feb 2005 10:14:00 -0500

Server clustering is available on Windows Server 2003 Enterprise Edition.

"Single Data Store" is not a service, it is a description. All data resides
on a single logical device physically connected to all host nodes. This can
be a SCSI array, a Fiber array, or a SAN. Ownership of this device is
arbitrated by the cluster service. Microsoft SQL DB clustering exists as a
failover technology only and has no distributed computing capabilities. It
is not a scale-out technology. One server owns the entire database and no
other server can access the data without moving the entire SQL instance to
another host. Active-Passive and Active-Active are not accurate
descriptions of the current SQL clustering technology but are somewhat
misleading holdovers from an earlier version.

Again, clustering is for availability and does not allow multiple
simultaneous connections to the data store from different host nodes. 

-- 
Geoff N. Hiten
Microsoft SQL Server MVP
Senior Database Administrator
Careerbuilder.com
I support the Professional Association for SQL Server
www.sqlpass.org
"Pankaj" <pankajchitriv@rediffmail.com(donotspam)> wrote in message
news:4A51BB01-D028-4B3B-9244-12EFA8469987@microsoft.com...
> Thanks Geoff.
>
> "Server Cluster" is a inbuild clustering service provided by Windows 2003
> Server.
>
> Just wondering, whether that Single Data Store is a seperate windows
system?
> If so what if that system breaks down? Is that the case that we do DB
> clustering only to distribute the processing capabilities?
>
> What I understood by Single Data Store means is there will be a system on
> which SQL DB will be created and there would be multiple servers accessing
> the same database. But this cannot be called as DB clustering as we don't
> have to configure any VIP to access the single data store. Can you clarify
> this please?
>
> Thanks a lot  again for your answers.
>
> Regards
> Pankaj A. Chitriv
>
> "Geoff N. Hiten" wrote:
>
> > Answers Inline
> >
> > -- 
> > Geoff N. Hiten
> > Microsoft SQL Server MVP
> > Senior Database Administrator
> > Careerbuilder.com
> >
> > I support the Professional Association for SQL Server
> > www.sqlpass.org
> >
> > "Pankaj" <pankajchitriv@rediffmail.com(donotspam)> wrote in message
> > news:847A2BE3-74E1-4B9E-9D61-EEE40D117155@microsoft.com...
> > > Hi, Below are few queries:
> > >
> > > 1. Say for 2 nodes cluster, Do we need to have 2 copies of
Databases( 1 on
> > > each node)
> > No.  Data is on shared storage and is controlled by one node at a time.
> > >
> > > 2. Hows does the data Synchronization between different nodes of
databases
> > > takes place?
> > There is no synchronization.  There is a single data store.  Access to
this
> > store is arbitrated by the cluster software.
> > >
> > > 3. In Active/Passive mode, does the passive node database is exactly
in
> > the
> > > same state (in terms of data) as that of Active?
> > >
> > Clustering is failover not scaleout technology.
> >
> > > 4. Is 'Server Cluster' specifically for DB clustering ?
> > I am not sure what you mean by "Server Cluster"?
> > >
> > > Thanks in advance,
> > > Pankaj A. Chitriv
> > >
> >
> >
> >

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