Installing > 1 instance on a cluster node?

#1

Hi,
I have a set of 4 servers coming in to be installed as a
cluster running Win 2003 Enterprise with SQL2000, all to
be connected through Fibre Channel to a SAN.
I am trying to figure out how many instances to install
in this cluster. I want to utilise all nodes, so there
will be at least 4 instances. What are the pros and cons
of installing more than 1 instance on a node? TIA!!

#2

Hi

If you install more than 1 instance on a node, you share the memory between
the number of instances. e.g. If you have 2 instances, the active instance
should only be configured to use 1/2 of the server's memory, otherwise on
failover, the other instance does not have enough. So, during normal
operation, 1/2 your memory on a server is not being used.

On a 4 way node, with 4 instances, it becomes 1/4 of the memory. The actual
memory will depend on the expected memory requirement for each instance.

You may want to look at 2 clusters, with 2 nodes each.

--
--------------------------------
Mike Epprecht, Microsoft SQL Server MVP
Epprecht Consulting (PTY) LTD
Johannesburg, South Africa
Mobile: +27-82-552-0268
IM: mike (AT) NOSPAMepprecht (DOT) net

Specialist SQL Server Solutions and Consulting

"Benny Koh" <anonymous (AT) discussions (DOT) microsoft.com> wrote

Quote:

Hi,
I have a set of 4 servers coming in to be installed as a
cluster running Win 2003 Enterprise with SQL2000, all to
be connected through Fibre Channel to a SAN.
I am trying to figure out how many instances to install
in this cluster. I want to utilise all nodes, so there
will be at least 4 instances. What are the pros and cons
of installing more than 1 instance on a node? TIA!!

#3

You actually install each instance on all nodes, unles you restrict certain
instances to certain node. I have a four node cluster with three instances,
configured as you describe. That way, each instance can use the full
resources of each node while still having full capacity in the event of a
failover. With a cluster, you will have to leave some resources available
if a node goes offline. Whether you leave some memory and processor
capability on all nodes or on just one node is your choice. Personally, I
have found the N-1 scenario the best.

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

"Benny Koh" <anonymous (AT) discussions (DOT) microsoft.com> wrote

Quote:

Hi,
I have a set of 4 servers coming in to be installed as a
cluster running Win 2003 Enterprise with SQL2000, all to
be connected through Fibre Channel to a SAN.
I am trying to figure out how many instances to install
in this cluster. I want to utilise all nodes, so there
will be at least 4 instances. What are the pros and cons
of installing more than 1 instance on a node? TIA!!

#4

I am a little confused here.
So If I have 4 nodes in a cluster and 4 instances, each
residing on 1 node, each node having 1 instance. This
means that each instance will only get 1/4 of the node
resources?
So which cluster is better? 2 2-node clusters or 1 4-node
clusters?

Benny

Quote:

-----Original Message-----
Hi

If you install more than 1 instance on a node, you share
the memory between
the number of instances. e.g. If you have 2 instances,
the active instance
should only be configured to use 1/2 of the server's
memory, otherwise on
failover, the other instance does not have enough. So,
during normal
operation, 1/2 your memory on a server is not being used.

On a 4 way node, with 4 instances, it becomes 1/4 of the
memory. The actual
memory will depend on the expected memory requirement for
each instance.

You may want to look at 2 clusters, with 2 nodes each.

--
--------------------------------
Mike Epprecht, Microsoft SQL Server MVP
Epprecht Consulting (PTY) LTD
Johannesburg, South Africa
Mobile: +27-82-552-0268
IM: mike (AT) NOSPAMepprecht (DOT) net

Specialist SQL Server Solutions and Consulting

"Benny Koh" <anonymous (AT) discussions (DOT) microsoft.com> wrote
in message
news:02e201c3d8d2$a8181c30$a501280a (AT) phx (DOT) gbl...
Hi,
I have a set of 4 servers coming in to be installed as
a
cluster running Win 2003 Enterprise with SQL2000, all to
be connected through Fibre Channel to a SAN.
I am trying to figure out how many instances to install
in this cluster. I want to utilise all nodes, so there
will be at least 4 instances. What are the pros and cons
of installing more than 1 instance on a node? TIA!!

.

#5

Hi Geoff,
can you please explain why you found N-1 to be the best
for you? Need to evaluate this configuration was well as
the 2 2-node clusters that Mike recommended.

Quote:

-----Original Message-----
You actually install each instance on all nodes, unles
you restrict certain
instances to certain node. I have a four node cluster
with three instances,
configured as you describe. That way, each instance can
use the full
resources of each node while still having full capacity
in the event of a
failover. With a cluster, you will have to leave some
resources available
if a node goes offline. Whether you leave some memory
and processor
capability on all nodes or on just one node is your
choice. Personally, I
have found the N-1 scenario the best.

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

"Benny Koh" <anonymous (AT) discussions (DOT) microsoft.com> wrote
in message
news:02e201c3d8d2$a8181c30$a501280a (AT) phx (DOT) gbl...
Hi,
I have a set of 4 servers coming in to be installed as
a
cluster running Win 2003 Enterprise with SQL2000, all to
be connected through Fibre Channel to a SAN.
I am trying to figure out how many instances to install
in this cluster. I want to utilise all nodes, so there
will be at least 4 instances. What are the pros and cons
of installing more than 1 instance on a node? TIA!!

.

#6

Hi

Geoff has the luxury of having a spare box, just waiting to take over one of
the nodes. In his scenario, if you loose 2 nodes, it does get interesting,
but then you have other things to worry about. In effect, it is
Active/Active/Active/Passive.

With 4 boxes, 2x2 nodes is easier to maintain as you have to worry less
about making sure that 4 instances are exactly the same over the cluster.

When you apply a SQL Service Pack, it takes the whole cluster offline. In a
2x2, you have only 1 cluster down at a time, whilst in a 1x4, everything is
offline and might not come up again (Murphy's law is applicable to clusters
too)

Depending on how much resilience you can afford, 2x2, 1x4 or 3x4 are all
good options.

Cheers
--------------------------------
Mike Epprecht, Microsoft SQL Server MVP
Epprecht Consulting (PTY) LTD
Johannesburg, South Africa
Mobile: +27-82-552-0268
IM: mike (AT) NOSPAMepprecht (DOT) net

Specialist SQL Server Solutions and Consulting

"Benny Koh" <anonymous (AT) discussions (DOT) microsoft.com> wrote

Quote:

Hi Geoff,
can you please explain why you found N-1 to be the best
for you? Need to evaluate this configuration was well as
the 2 2-node clusters that Mike recommended.

-----Original Message-----
You actually install each instance on all nodes, unles
you restrict certain
instances to certain node. I have a four node cluster
with three instances,
configured as you describe. That way, each instance can
use the full
resources of each node while still having full capacity
in the event of a
failover. With a cluster, you will have to leave some
resources available
if a node goes offline. Whether you leave some memory
and processor
capability on all nodes or on just one node is your
choice. Personally, I
have found the N-1 scenario the best.

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

"Benny Koh" <anonymous (AT) discussions (DOT) microsoft.com> wrote
in message
news:02e201c3d8d2$a8181c30$a501280a (AT) phx (DOT) gbl...
Hi,
I have a set of 4 servers coming in to be installed as
a
cluster running Win 2003 Enterprise with SQL2000, all to
be connected through Fibre Channel to a SAN.
I am trying to figure out how many instances to install
in this cluster. I want to utilise all nodes, so there
will be at least 4 instances. What are the pros and cons
of installing more than 1 instance on a node? TIA!!

.

#7

Comments Inline
"Mike Epprecht [SQL Server MVP]" <mike (AT) NOSPAMepprecht (DOT) net> wrote

Quote:

Hi

Geoff has the luxury of having a spare box, just waiting to take over one
of
the nodes. In his scenario, if you loose 2 nodes, it does get interesting,
but then you have other things to worry about. In effect, it is
Active/Active/Active/Passive.

As Mike notes, I have a 'spare' system that can take over. That way, I can

set up my SQL instances to use all the resources on each node and still have
failover room. As he also notes, things get interesting when more than node
goes down. However, it isn't that hard. I simply reduce the memory
footprint of each instance and in theory, I can run them all on one box. I
haven't tried that, but I have run with two nodes offline during off-peak
hours.

Quote:

With 4 boxes, 2x2 nodes is easier to maintain as you have to worry less
about making sure that 4 instances are exactly the same over the cluster.

Yep. Matching the nodes isn't simple, but good documentation and practices

will help. If you don't have those you won't have a highly available system
anyway.

Quote:

When you apply a SQL Service Pack, it takes the whole cluster offline. In
a
2x2, you have only 1 cluster down at a time, whilst in a 1x4, everything
is
offline and might not come up again (Murphy's law is applicable to
clusters
too)

Applying a service pack only takes the particular instance offline. No

different than with a 2-node cluster. And yes, Murphy is the patron saint
of computer science. Rolling reboots can take a while (especially on these
Unisys boxes), but you aren't any more vulnerable than on a 2-node cluster.

Quote:

Depending on how much resilience you can afford, 2x2, 1x4 or 3x4 are all
good options.

3x4 works for me because I really needed 3 instances and SQL will only

install on 4 nodes per instance, so this is all we can do for now. Perfect
match. YMMV.

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

Quote:

Cheers
--------------------------------
Mike Epprecht, Microsoft SQL Server MVP
Epprecht Consulting (PTY) LTD
Johannesburg, South Africa
Mobile: +27-82-552-0268
IM: mike (AT) NOSPAMepprecht (DOT) net

Specialist SQL Server Solutions and Consulting

"Benny Koh" <anonymous (AT) discussions (DOT) microsoft.com> wrote in message
news:082901c3d9af$930e54c0$a401280a (AT) phx (DOT) gbl...
Hi Geoff,
can you please explain why you found N-1 to be the best
for you? Need to evaluate this configuration was well as
the 2 2-node clusters that Mike recommended.

-----Original Message-----
You actually install each instance on all nodes, unles
you restrict certain
instances to certain node. I have a four node cluster
with three instances,
configured as you describe. That way, each instance can
use the full
resources of each node while still having full capacity
in the event of a
failover. With a cluster, you will have to leave some
resources available
if a node goes offline. Whether you leave some memory
and processor
capability on all nodes or on just one node is your
choice. Personally, I
have found the N-1 scenario the best.

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

"Benny Koh" <anonymous (AT) discussions (DOT) microsoft.com> wrote
in message
news:02e201c3d8d2$a8181c30$a501280a (AT) phx (DOT) gbl...
Hi,
I have a set of 4 servers coming in to be installed as
a
cluster running Win 2003 Enterprise with SQL2000, all to
be connected through Fibre Channel to a SAN.
I am trying to figure out how many instances to install
in this cluster. I want to utilise all nodes, so there
will be at least 4 instances. What are the pros and cons
of installing more than 1 instance on a node? TIA!!

.

#8

Hi Geoff and Mike,
thanks for all your comments!
I will factor in these factors when I make my
recommendation.

Benny

Quote:

-----Original Message-----
Comments Inline
"Mike Epprecht [SQL Server MVP]"
mike (AT) NOSPAMepprecht (DOT) net> wrote in message
news:%23JH%23w9b2DHA.2528 (AT) TK2MSFTNGP09 (DOT) phx.gbl...
Hi

Geoff has the luxury of having a spare box, just
waiting to take over one
of
the nodes. In his scenario, if you loose 2 nodes, it
does get interesting,
but then you have other things to worry about. In
effect, it is
Active/Active/Active/Passive.

As Mike notes, I have a 'spare' system that can take
over. That way, I can
set up my SQL instances to use all the resources on each
node and still have
failover room. As he also notes, things get interesting
when more than node
goes down. However, it isn't that hard. I simply reduce
the memory
footprint of each instance and in theory, I can run them
all on one box. I
haven't tried that, but I have run with two nodes offline
during off-peak
hours.

With 4 boxes, 2x2 nodes is easier to maintain as you
have to worry less
about making sure that 4 instances are exactly the same
over the cluster.

Yep. Matching the nodes isn't simple, but good
documentation and practices
will help. If you don't have those you won't have a
highly available system
anyway.

When you apply a SQL Service Pack, it takes the whole
cluster offline. In
a
2x2, you have only 1 cluster down at a time, whilst in
a 1x4, everything
is
offline and might not come up again (Murphy's law is
applicable to
clusters
too)

Applying a service pack only takes the particular
instance offline. No
different than with a 2-node cluster. And yes, Murphy is
the patron saint
of computer science. Rolling reboots can take a while
(especially on these
Unisys boxes), but you aren't any more vulnerable than on
a 2-node cluster.

Depending on how much resilience you can afford, 2x2,
1x4 or 3x4 are all
good options.

3x4 works for me because I really needed 3 instances and
SQL will only
install on 4 nodes per instance, so this is all we can
do for now. Perfect
match. YMMV.

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

Cheers
--------------------------------
Mike Epprecht, Microsoft SQL Server MVP
Epprecht Consulting (PTY) LTD
Johannesburg, South Africa
Mobile: +27-82-552-0268
IM: mike (AT) NOSPAMepprecht (DOT) net

Specialist SQL Server Solutions and Consulting

"Benny Koh" <anonymous (AT) discussions (DOT) microsoft.com> wrote
in message
news:082901c3d9af$930e54c0$a401280a (AT) phx (DOT) gbl...
Hi Geoff,
can you please explain why you found N-1 to be the
best
for you? Need to evaluate this configuration was well
as
the 2 2-node clusters that Mike recommended.

-----Original Message-----
You actually install each instance on all nodes,
unles
you restrict certain
instances to certain node. I have a four node
cluster
with three instances,
configured as you describe. That way, each instance
can
use the full
resources of each node while still having full
capacity
in the event of a
failover. With a cluster, you will have to leave
some
resources available
if a node goes offline. Whether you leave some
memory
and processor
capability on all nodes or on just one node is your
choice. Personally, I
have found the N-1 scenario the best.

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

"Benny Koh" <anonymous (AT) discussions (DOT) microsoft.com
wrote
in message
news:02e201c3d8d2$a8181c30$a501280a (AT) phx (DOT) gbl...
Hi,
I have a set of 4 servers coming in to be
installed as
a
cluster running Win 2003 Enterprise with SQL2000,
all to
be connected through Fibre Channel to a SAN.
I am trying to figure out how many instances to
install
in this cluster. I want to utilise all nodes, so
there
will be at least 4 instances. What are the pros
and cons
of installing more than 1 instance on a node? TIA!!

.

.

#9

One more question:
If I want to install SQL patches (eg Service Pack 3a), on
an instance, will the SQL downtime for this instance be
longer in a 2-node cluster versus a 4-node cluster?

Benny

Quote:

-----Original Message-----
Comments Inline
"Mike Epprecht [SQL Server MVP]"
mike (AT) NOSPAMepprecht (DOT) net> wrote in message
news:%23JH%23w9b2DHA.2528 (AT) TK2MSFTNGP09 (DOT) phx.gbl...
Hi

Geoff has the luxury of having a spare box, just
waiting to take over one
of
the nodes. In his scenario, if you loose 2 nodes, it
does get interesting,
but then you have other things to worry about. In
effect, it is
Active/Active/Active/Passive.

As Mike notes, I have a 'spare' system that can take
over. That way, I can
set up my SQL instances to use all the resources on each
node and still have
failover room. As he also notes, things get interesting
when more than node
goes down. However, it isn't that hard. I simply reduce
the memory
footprint of each instance and in theory, I can run them
all on one box. I
haven't tried that, but I have run with two nodes offline
during off-peak
hours.

With 4 boxes, 2x2 nodes is easier to maintain as you
have to worry less
about making sure that 4 instances are exactly the same
over the cluster.

Yep. Matching the nodes isn't simple, but good
documentation and practices
will help. If you don't have those you won't have a
highly available system
anyway.

When you apply a SQL Service Pack, it takes the whole
cluster offline. In
a
2x2, you have only 1 cluster down at a time, whilst in
a 1x4, everything
is
offline and might not come up again (Murphy's law is
applicable to
clusters
too)

Applying a service pack only takes the particular
instance offline. No
different than with a 2-node cluster. And yes, Murphy is
the patron saint
of computer science. Rolling reboots can take a while
(especially on these
Unisys boxes), but you aren't any more vulnerable than on
a 2-node cluster.

Depending on how much resilience you can afford, 2x2,
1x4 or 3x4 are all
good options.

3x4 works for me because I really needed 3 instances and
SQL will only
install on 4 nodes per instance, so this is all we can
do for now. Perfect
match. YMMV.

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

Cheers
--------------------------------
Mike Epprecht, Microsoft SQL Server MVP
Epprecht Consulting (PTY) LTD
Johannesburg, South Africa
Mobile: +27-82-552-0268
IM: mike (AT) NOSPAMepprecht (DOT) net

Specialist SQL Server Solutions and Consulting

"Benny Koh" <anonymous (AT) discussions (DOT) microsoft.com> wrote
in message
news:082901c3d9af$930e54c0$a401280a (AT) phx (DOT) gbl...
Hi Geoff,
can you please explain why you found N-1 to be the
best
for you? Need to evaluate this configuration was well
as
the 2 2-node clusters that Mike recommended.

-----Original Message-----
You actually install each instance on all nodes,
unles
you restrict certain
instances to certain node. I have a four node
cluster
with three instances,
configured as you describe. That way, each instance
can
use the full
resources of each node while still having full
capacity
in the event of a
failover. With a cluster, you will have to leave
some
resources available
if a node goes offline. Whether you leave some
memory
and processor
capability on all nodes or on just one node is your
choice. Personally, I
have found the N-1 scenario the best.

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

"Benny Koh" <anonymous (AT) discussions (DOT) microsoft.com
wrote
in message
news:02e201c3d8d2$a8181c30$a501280a (AT) phx (DOT) gbl...
Hi,
I have a set of 4 servers coming in to be
installed as
a
cluster running Win 2003 Enterprise with SQL2000,
all to
be connected through Fibre Channel to a SAN.
I am trying to figure out how many instances to
install
in this cluster. I want to utilise all nodes, so
there
will be at least 4 instances. What are the pros
and cons
of installing more than 1 instance on a node? TIA!!

.

.

#10

They all install simultaneously so there will be no perceived difference.

--
--------------------------------
Mike Epprecht, Microsoft SQL Server MVP
Epprecht Consulting (PTY) LTD
Johannesburg, South Africa
Mobile: +27-82-552-0268
IM: mike (AT) NOSPAMepprecht (DOT) net

Specialist SQL Server Solutions and Consulting

"Benny Koh" <anonymous (AT) discussions (DOT) microsoft.com> wrote

Quote:

One more question:
If I want to install SQL patches (eg Service Pack 3a), on
an instance, will the SQL downtime for this instance be
longer in a 2-node cluster versus a 4-node cluster?

Benny
-----Original Message-----
Comments Inline
"Mike Epprecht [SQL Server MVP]"
mike (AT) NOSPAMepprecht (DOT) net> wrote in message
news:%23JH%23w9b2DHA.2528 (AT) TK2MSFTNGP09 (DOT) phx.gbl...
Hi

Geoff has the luxury of having a spare box, just
waiting to take over one
of
the nodes. In his scenario, if you loose 2 nodes, it
does get interesting,
but then you have other things to worry about. In
effect, it is
Active/Active/Active/Passive.

As Mike notes, I have a 'spare' system that can take
over. That way, I can
set up my SQL instances to use all the resources on each
node and still have
failover room. As he also notes, things get interesting
when more than node
goes down. However, it isn't that hard. I simply reduce
the memory
footprint of each instance and in theory, I can run them
all on one box. I
haven't tried that, but I have run with two nodes offline
during off-peak
hours.

With 4 boxes, 2x2 nodes is easier to maintain as you
have to worry less
about making sure that 4 instances are exactly the same
over the cluster.

Yep. Matching the nodes isn't simple, but good
documentation and practices
will help. If you don't have those you won't have a
highly available system
anyway.

When you apply a SQL Service Pack, it takes the whole
cluster offline. In
a
2x2, you have only 1 cluster down at a time, whilst in
a 1x4, everything
is
offline and might not come up again (Murphy's law is
applicable to
clusters
too)

Applying a service pack only takes the particular
instance offline. No
different than with a 2-node cluster. And yes, Murphy is
the patron saint
of computer science. Rolling reboots can take a while
(especially on these
Unisys boxes), but you aren't any more vulnerable than on
a 2-node cluster.

Depending on how much resilience you can afford, 2x2,
1x4 or 3x4 are all
good options.

3x4 works for me because I really needed 3 instances and
SQL will only
install on 4 nodes per instance, so this is all we can
do for now. Perfect
match. YMMV.

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

Cheers
--------------------------------
Mike Epprecht, Microsoft SQL Server MVP
Epprecht Consulting (PTY) LTD
Johannesburg, South Africa
Mobile: +27-82-552-0268
IM: mike (AT) NOSPAMepprecht (DOT) net

Specialist SQL Server Solutions and Consulting

"Benny Koh" <anonymous (AT) discussions (DOT) microsoft.com> wrote
in message
news:082901c3d9af$930e54c0$a401280a (AT) phx (DOT) gbl...
Hi Geoff,
can you please explain why you found N-1 to be the
best
for you? Need to evaluate this configuration was well
as
the 2 2-node clusters that Mike recommended.

-----Original Message-----
You actually install each instance on all nodes,
unles
you restrict certain
instances to certain node. I have a four node
cluster
with three instances,
configured as you describe. That way, each instance
can
use the full
resources of each node while still having full
capacity
in the event of a
failover. With a cluster, you will have to leave
some
resources available
if a node goes offline. Whether you leave some
memory
and processor
capability on all nodes or on just one node is your
choice. Personally, I
have found the N-1 scenario the best.

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

"Benny Koh" <anonymous (AT) discussions (DOT) microsoft.com
wrote
in message
news:02e201c3d8d2$a8181c30$a501280a (AT) phx (DOT) gbl...
Hi,
I have a set of 4 servers coming in to be
installed as
a
cluster running Win 2003 Enterprise with SQL2000,
all to
be connected through Fibre Channel to a SAN.
I am trying to figure out how many instances to
install
in this cluster. I want to utilise all nodes, so
there
will be at least 4 instances. What are the pros
and cons
of installing more than 1 instance on a node? TIA!!

.

.