Re: N+1 Configuration

We never had a SQL instance fail to come up and we must have done probably
100 failovers across the 16 instances before we noticed it :-)

--
HTH,
Jasper Smith (SQL Server MVP)
http://www.sqldbatips.com


"Linchi Shea" <LinchiShea@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
news:1EC01BFF-C9FB-40E8-9A4D-603F5A4DAA80@xxxxxxxxxxxxxxxx
Good point on the impact on tempdb, Jasper!

Interestingly SQL actually seemed to cope pretty well with it and retried
it's operations and came up normally once the mount point was fully
online without any manual intervention.

I wonder if that's the result of the built-in read retries or something
special to the startup process. If it's the built-in read retries, it's
conceivable that if the tempdb volume comes up very late, the startup may
not
succeed every time. Did it always succeed in the cases you have seen?

Linchi

"Jasper Smith" wrote:

Good point. In some initial testing we forgot to do that and found that
SQL
Server would try and start before the Tempdb mount point came fully
online.
You get a bunch of IO errors in the errorlog during startup.
Interestingly
SQL actually seemed to cope pretty well with it and retried it's
operations
and came up normally once the mount point was fully online without any
manual intervention. This is obviously not ideal though so we enforce the
dependencies as part of our install scripts.

--
HTH,
Jasper Smith (SQL Server MVP)
http://www.sqldbatips.com


"Linchi Shea" <LinchiShea@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
news:A2B44570-5D0C-45CA-B77B-865FBBAE4E04@xxxxxxxxxxxxxxxx
There is a dependency issue that is worth pointing out. While you need
to
make a mounted volume dependent on its root disk drive, there is no
requirement to have any dependency between the SQL Server resource and
a
mounted volume disk resource that you'll place database files on. This
is
different from using a drive letter, in which case the SQL Server
resource
must depend on the disk resource.

What this means is that you can have a mounted volume that is offline
with
some database files on it, and the SQL Server instance can still come
online
unless you specify the dependency yourself.

The feedback I got from MS is that they may consider enforcing that
dependency in a future release.

Linchi

"DTully" wrote:

Thanks Jasper. I found that doc and it helps.

So, I'm all straight on using mount points and now only a single root
LUN
will need to be presented by each new node.

I do have one additional question. The current cluster is
Active/Passive.
I'm adding a new third server that has four LUNS presented to only it
so
far
-not to the failover server at this moment. I've clustered this third
server
without any issues. But looking in the cluster admin tool, it did not
add
it's LUNs to the cluster. And if I try to add a new physical disk
resource,
none of its LUNs are shown in the drop down box to select from. Might
this be
because the failover node cannot see it? Do I have to paused (or shut
down)
the other nodes first? Even maybe the nodes that will never help in
failover
(hope not as those might be in production later)?

I've added LUNS before but only in an Active/Passive configuration and
once
it was partitioned I could add it as a clustered resource with no
problems.

Can't say thank you enough for all the help.
Darin

"Jasper Smith" wrote:

Every clustered instance will require it's own drive letter but off
that you
can hang a bunch of mount points. We tend to have

Mounts\SQLData
Mounts\SQLLogs
Mounts\SQLDumps
Mounts\SQLTemp

We have tested upto 16 instances on a 4 node cluster all using a
single
drive letter and then mount points as above for each and not had any
problems

How to configure volume mount points on a Microsoft Cluster Server
http://support.microsoft.com/kb/280297/

--
HTH,
Jasper Smith (SQL Server MVP)
http://www.sqldbatips.com


"DTully" <DTully@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
news:997AEB50-0F2D-46D2-9DDC-718B60B0FE67@xxxxxxxxxxxxxxxx
Wow! Thank you both!

The team brought up the idea of using NTFS junction points (the
same
thing?). Is there any good documentation of this? So it does
appear
that
no
two instances of SQL can be using the same drive letter though
(even
if,
as
Linchi suggested, mounting all other drives under that drive
letter).
We
have
consistency between servers that all data is on drive F, etc. But
that's a
trade off for the ability to have fewer failover servers per
grouping
of
active servers.

Thanks!
Darin

"Linchi Shea" wrote:

To add to what Geoff said about mount points.

If you use one drive letter per SQL instance and mount all other
drives
for
that instance under that drive letter, you can technically have
20+
instances
in the cluster. But hopefully, you are not considering that many
instances in
a single cluster.

I have tested various scenarios of using mounted volumes in a
SQL2005
cluster. There is no major issue with using mounted volumes in
SQL
2005.
But
note that some of the disk space related utilities are not 'mount
point
aware', thus won't give you the total space info for the entire
drive
tree or
may not be aware that there is a separate drive mounted
underneath a
drive
letter. So you may have to revise your space monitoring setup.

Linchi



"DTully" wrote:

Thanks Linchi!

I think I see the light now. So one clustered OS instance with
multiple
nodes, with multiple SQL installations, etc, etc.

Only problem I see then is each SQL named instance would have
to
use
different drives letters for the SQL's data files, log files,
etc
since
if
two instances failed over to the same failover server the
drives
would
clash.
Correct? Wow, not sure there are enough drive letters for 6 SQL
instances
using 3-4 drive letters each.

OK - thanks for getting my head on straight.
Darin

"Linchi Shea" wrote:

How could a server not run two clusters in a N+1
configuation.

If I understand this statement correctly, we have some
fundamental
problem/misconception here. A node can't be in two different
clusters
simultaneously. N+1 simply means that this particular cluster
would
have as
many as N+1 nodes, and N of those will be configured to have
apps
(i.e. SQL
isntances in this cases) running in the normal operating
mode,
and
the other
one node will be a spare, to which the other nodes may
failover.
So,
we
definitely do not have two clusters here.

Linchi

"DTully" wrote:

Well - first TIA!

We have an Active/Passive cluster running W2K3 Enterprise
X64
Sp1,
32GB RAM
and SQL Server 2005. We're moving to a N+1 configuration
(and
then
maybe N+M
later), but I'm running into an error.

After I cluster the third server and try adding the
failover
node
(it's the
same failover node for the existing cluster), I get the
following
error in
the log:

2006-08-30 15:04:30.432 [ERR ] SJCFODBMS016M: This node is
a
member
of a
different cluster: "SJCADDBMS014V.corp.shop.com".
(hr=0x8007000d,
{EBC8AEFF-10C3-4D5B-AC17-FC0F4C3871B7},
{0B5C1D35-1CA5-4597-B1A7-DCD4D64F55C6}, 1, 1, 1), (null)
2006-08-30 15:04:30.495 [ERR ] SJCKWDBMS011V: Checking
cluster
membership...
(hr=0x8007000d, {EBC8AEFF-10C3-4D5B-AC17-FC0F4C3871B7},
{06AB21DD-D8C7-453D-845E-50423BEACA38}, 0, 1, 1), (null)
2006-08-30 15:04:30.557 [ERR ] SJCKWDBMS011V: (null)
(hr=0x8007000d,
{FDC75680-7DBB-42CA-8003-E4CDB01FF062},
{EBC8AEFF-10C3-4D5B-AC17-FC0F4C3871B7}, 0, 8, 8), (null)
2006-08-30 15:04:30.604 [INFO] [MT]
[CTaskAnalyzeClusterBase]
Exiting task.
The task was not cancelled.

In the wizard I get the same error (that the other node is
a
member
of a
different cluster) and the install then fails.

I also tried to install the new cluster directly on the
failover
server
(cleaned it off the third node first) and it won't even
istall
and
returns
the same error.

This can't be right. How could a server not run two
clusters
in a
N+1
configuation. I'm really aiming for N+M with 6 active and 2
dedicated FO
servers. But I'm stuck at the moment.

Thanks and again - TIA!!
Darin








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