Cluster Resource Dependencies - 02-04-2010 , 06:38 AM
We have a Win Srvr 2003 3 node cluster running SQL 2008 Enterprise. The SQL
srvr uses multiple mount points along with the other SQL Server cluster
resources . The mount groups are separated into 2 separate volume groups for
mounting on separate drive letters to facilliate those databases requiring
SRDF frame replication for DR.
Is there a comprehensive document, link or discussion group which discusses
cluster resource dependencies that should be employed in a production cluster
as a best practice?
Should the disk volume groups have a dependency on the SQL network name for
that resource to be on-line before it attempts to perfrom any disk mounts?
Should the second disk volume group have a dependency on the first to be
RE: Cluster Resource Dependencies - 02-05-2010 , 02:40 AM
Here are some very good articles for configuring SQL Server cluster:
SQL Server 2005 Failover Clustering White Paper
Server Clusters: Cluster Configuration Best Practices for Windows Server
Installing a SQL Server 2008 Failover Cluster
Regarding disk amounts, the article "Before installing failover clustering"
mentions it well:
SQL Server supports mount points; the clustered installations of SQL Server
are limited to the number of available drive letters. Assuming that you use
only one drive letter for the operating system, and all other drive letters
are available as normal cluster drives or cluster drives hosting mount
points, you are limited to a maximum of 25 instances of SQL Server per
A mounted volume, or mount point, allows you to use a single drive letter
to refer to many disks or volumes. If you have a drive letter D: that
refers to a regular disk or volume, you can connect or "mount" additional
disks or volumes as directories under drive letter D: without the
additional disks or volumes requiring drive letters of their own.
Additional mount point considerations for SQL Server failover clustering:
SQL Server Setup requires that the base drive of a mounted drive has an
associated drive letter. For failover cluster installations, this base
drive must be a clustered drive. Volume GUIDs are not supported in this
The base drive, the one with the drive letter, cannot be shared among
failover cluster instances. This is a normal restriction for failover
clusters, but is not a restriction on stand-alone, multi-instance servers.
Take extra care when setting up your failover cluster to ensure that both
the base drive and the mounted disks or volumes are all listed as resources
in the resource group. SQL Server Setup validates drive configuration as
part of a failover cluster installation.
SQL Server Setup automatically sets dependencies between the SQL Server
cluster group and the disks that will be in the failover cluster. Do not
set dependencies for disks before Setup.
As you can see, SQL Server setup will automatically sets dependencies. It
is not recommended that you set dependencies for disks before setup.