Re: Quorum Disk or Majority Node?

Doesn't phase me in the slightest, simply because I see more unsupported
code deployed in mission crtical business applications than I see supported
code. Always has been that way and always will be that way. All
"supported" really means is that there is someone to point the finger at and
blame when something goes wrong. That makes "unsupported" pretty much the
definition of any application that is ever developed in house as well as a
LOT of 3rd party applications where every issue is always blamed on
something else.

You write the best code possible and test it as well as possible and then
you deploy it into production and deal with anything that happens after it
is running the business. That is a simple fact of life in the IT industry
and always has been. Just because it is supported doesn't mean that it will
work nor does it mean it will stay working. Save the speech about how that
is really unprofessional and a really bad idea. I've designed systems used
by EMTs on ambulances, applications used in operating rooms, and several
other types of applications where the application failing meant that someone
could possibly die. I know what mission critical is and even in those types
of systems, the same thing applies, they do have bugs and things do go wrong
with them and in many cases, there isn't anyone to point the finger at, but
someone always has to fix the issue. I have yet to see a bug-free
application written.

--
Mike
http://www.solidqualitylearning.com
Disclaimer: This communication is an original work and represents my sole
views on the subject. It does not represent the views of any other person
or entity either by inference or direct reference.


"DAVID A BERMINGHAM" <david.bermingham@xxxxxxxxxxxxxxxxxxx> wrote in message
news:uSTs0zBKGHA.1288@xxxxxxxxxxxxxxxxxxxxxxx
You are correct, but running unsupported software is risky business,
especially for business critical applications. A test environment, I
say -
go for it. Otherwise, I wouldn't want to be around when it all falls
apart
and the CEO says - who installed unsupport software?

"Michael Hotek" <mike@xxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
news:OGTZngBKGHA.3728@xxxxxxxxxxxxxxxxxxxxxxx
Database Mirroring is already an option. It is in the product and being
used at several customer sites. No, it is not officially supported, but
it
does work.

What is described is exactly what I've seen for most of the
implementations.
Instead of deploying clustering, they are going with Database Mirroring
and
in a couple of cases, clustering is being replaced with a Database
Mirroring
implementation.

--
Mike
http://www.solidqualitylearning.com
Disclaimer: This communication is an original work and represents my sole
views on the subject. It does not represent the views of any other
person
or entity either by inference or direct reference.


"DAVID A BERMINGHAM" <david.bermingham@xxxxxxxxxxxxxxxxxxx> wrote in
message
news:eQO3wkAKGHA.2828@xxxxxxxxxxxxxxxxxxxxxxx
After a quick Google I am sure that you need at least a 3-Node cluster
for
a
MNS...


http://www.microsoft.com/technet/prodtechnol/windowsserver2003/technologies/clustering/majnode.mspx#EDAA

See "Sizing a Majority Node Set Cluster"

When SQL Server 2005 starts supporting database mirroring there is
going
to
be an option similar to what you describe. You can have a 2-Node SQL
"High
Availability Operating Mode" cluster, and have a 3rd server as a
"Witness"
server. This Witness Server can be running any version of SQL,
including
the free SQL 2005 Express Edition, and it will never be called into
service
as a live SQL Server. Note that this solution still does not support
shared storage and it does not address the applications that may be on
top
of SQL server.

http://www.microsoft.com/technet/prodtechnol/sql/2005/dbmirror.mspx

--
DISCLAIMER: I am a SteelEye Engineer with years of experience
implementing
HA and DR for WIndows solutions including Exchange and SQL server.


DAVID A BERMINGHAM" <david.bermingham@xxxxxxxxxxxxxxxxxxx> wrote in
message
news:eACDBUAKGHA.2248@xxxxxxxxxxxxxxxxxxxxxxx
I believe that all three nodes need to be part of the cluster, i.e.,
running
SQL, but I am not 100% positive. I am usually in a competitive
situation
with a customer proposing MNS with geographically disperse cluster.
When
they realize that they will need a 3rd node in the DR center, they
usually
choose our solution because we can do it with just 2 nodes.

--
DISCLAIMER: I am a SteelEye Engineer with years of experience
implementing
HA and DR for WIndows solutions including Exchange and SQL server.

"GNocent" <GNocent@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
news:704AD7C0-A076-48FE-A631-06FEBD8109F6@xxxxxxxxxxxxxxxx
The solution that interested me was this one :
* Site 1 & Site 2 have hardware replicated storage and are connected
via
SAN.
* Site 3 is just connected via network and has only local disks.
* 3 nodes are part of the cluster (1 on each site)
* SQLServer instance can be hosted on node 1 or 2 only
* node 3 is only here for Quorum vote (not eligible for SQLServer
instance)

Is that possible without 3rd party software ?
If you can explain me quickly why or why not, i would really
appreciate
(the
whitepaper is not very explicit) !

Thanks.

Guillaume.
=====================================
"DAVID A BERMINGHAM" wrote:

What if for some reason you wanted to do a MNS and all 3 nodes
where
attached to the same SAN? Not a good idea, but that would still
be
a
MNS
and it does not require any third party products. No application
with
any
dynamic data supports MNS without some sort of shared disk,
whether
iSCSI,
SCSI, SAN or replicated disk.

"Geoff N. Hiten" <SQLCraftsman@xxxxxxxxx> wrote in message
news:eM1JRF3JGHA.1028@xxxxxxxxxxxxxxxxxxxxxxx
How about:

SQL Server does not NATIVELY support MNS clustering. Third
party
add-ons
may alter this behavior.

--
Geoff N. Hiten
Senior Database Administrator
Microsoft SQL Server MVP



"DAVID A BERMINGHAM" <david.bermingham@xxxxxxxxxxxxxxxxxxx>
wrote
in
message
news:eKdpQd2JGHA.1132@xxxxxxxxxxxxxxxxxxxxxxx
I would disagree with Geoff's statement that SQL Server does
not
support
majority node clusters, unless he can point us to the relevant
MS
documentation. I have many customers doing MNS and SQL server
implementations; as long as you understand the requirements
and
limitations.

I believe MNS were introduced to facilitate clustering across
remote
locations, hence no shared storage. Obviously, you have to
have
a
replacement for that shared storage so that the SQL data is
available on
the
passive node in the event of a failure. What that means is
that
you
need
to
do some sort of replication, usually a third party product
such
as
NSI
DoubleTake for replication.

The other requirement is that a majority of the servers need
to
be
available
in order for a failover to take place. So that means you need
to
have
at
least 3 nodes in your cluster in order to have a failover,
because
in a
two
node cluster if one node fails you only have one node left,
and
1
of
2
is
not a majority. You need at least 2 out of 3 nodes to have a
majority.

In a local cluster where shared storage is available, you will
want
to
go
with the traditional quorum based clustering. If you have no
shared
storage, you will want to go with MNS and data replication.

Alternatively you can ditch MSCS altogether and go with a
third
party
solution such as LifeKeeper Protection Suite for SQL Server
from
SteelEye
Technology which is a HA and DR solution combined which
eliminates
the
need
for MSCS, MNS, shared storage and a quorum device.

--
DISCLAIMER: I am a SteelEye Engineer with years of experience
implementing
HA and DR for WIndows solutions including Exchange and SQL
server.


"GNocent" <GNocent@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
news:E6E414F7-795A-42A4-9D7E-7AEF21FACEB2@xxxxxxxxxxxxxxxx
I found a very interesting article here :





http://www.microsoft.com/windowsserver2003/techinfo/overview/clustergeo.mspx

The chapter "Three-Site Majority Node Set Quorum in
Geographically
Dispersed
Clusters to Facilitate Automatic Failover" was the exact
solution
for
some
of
my split brain problems, so I wanted to try this solution.

Do you mean that it is a non applicable solution with
SQLServer
?
Why ? (I was thinking that the impact was limited to
Quorum+MSCS,
not
clustered resources !)

Thanks for your reply.

Guillaume.

=======================
"Geoff N. Hiten" wrote:

SQL Server does not support Majority Node Clusters.

--
Geoff N. Hiten
Senior Database Administrator
Microsoft SQL Server MVP



"Kevin Antel" <kevina@xxxxxxxxxxx> wrote in message
news:um8P7Y5FGHA.208@xxxxxxxxxxxxxxxxxxxxxxx
New to Windows MCS 2003 is the Majority Node Set option,
does
anyone
have
any experience where Majority Node is better than Quorum
or
vica
versa?






















.

Relevant Pages

  • Re: Quorum Disk or Majority Node?
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  • Re: Quorum Disk or Majority Node?
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