In this post I want to describe basic terms used in windows cluster. Let's have a look :
Cluster Resource is anything that you want clustered or virtualized.
SQL Server Cluster includes :
Cluster group is a group of related cluster resources. You can only fail over the entire group not the individual resources.
In the context of cluster a shared disk is a disk that can be owned over time by any configured node in the cluster but it can be owned by one node at a time.
Each resource has a LooksAlive lightweight check to see whether it appears to be working. For the SQL Server Service resource , this is a query to the operating system to see whether it looks like the service is up.
Each resource also has IsAlive check that is bit more through. For thacte SQL Server Service resource , the IsAlive check is a simple query against the master database.This actually verifies that the cluster service can connect to SQL Server and retrieve a small result set within the configured time limit.
There are time when looksalive check succeeds but IsAlive check fails. When the IsAlive check fails the configured number of times, it causes the group to fail.
Quorum is the agreed-upon place for storing information common to the windows cluster. Microsoft Windows clustering stores this information on shared disk called Quorum disk. The Quorum disk is disk resource in the same resource group that also has the windows cluster virtual name and the Windows cluster IP address. This group can reside on any node in the cluster and can be failed between nodes without disrupting the activity of the other clustered groups. The is often called the windows cluster group or the quorum group.
Along with the data stored on the quorum, registry keys exist that need to be kept in the sync. The quorum stored information about what ' checkpointed' registry keys have changed. A checkpointed key can be identified by it's existence in the cluster registry key hive. SQL Server set up adds several of it's keys to the checkpoint list , including the keys that store the location of the master database data and log and the location of the SQL server error log. The propagation of changes to these keys to other nodes in the cluster is called registry cloning.
Cluster Resource is anything that you want clustered or virtualized.
SQL Server Cluster includes :
- The SQL Server virtual name
- One or more SQL Server IP addresses
- The SQL Server Service
- The SQL Server Agent Service
- The Full Text resource.
Cluster group is a group of related cluster resources. You can only fail over the entire group not the individual resources.
In the context of cluster a shared disk is a disk that can be owned over time by any configured node in the cluster but it can be owned by one node at a time.
Each resource has a LooksAlive lightweight check to see whether it appears to be working. For the SQL Server Service resource , this is a query to the operating system to see whether it looks like the service is up.
Each resource also has IsAlive check that is bit more through. For thacte SQL Server Service resource , the IsAlive check is a simple query against the master database.This actually verifies that the cluster service can connect to SQL Server and retrieve a small result set within the configured time limit.
There are time when looksalive check succeeds but IsAlive check fails. When the IsAlive check fails the configured number of times, it causes the group to fail.
Quorum is the agreed-upon place for storing information common to the windows cluster. Microsoft Windows clustering stores this information on shared disk called Quorum disk. The Quorum disk is disk resource in the same resource group that also has the windows cluster virtual name and the Windows cluster IP address. This group can reside on any node in the cluster and can be failed between nodes without disrupting the activity of the other clustered groups. The is often called the windows cluster group or the quorum group.
Along with the data stored on the quorum, registry keys exist that need to be kept in the sync. The quorum stored information about what ' checkpointed' registry keys have changed. A checkpointed key can be identified by it's existence in the cluster registry key hive. SQL Server set up adds several of it's keys to the checkpoint list , including the keys that store the location of the master database data and log and the location of the SQL server error log. The propagation of changes to these keys to other nodes in the cluster is called registry cloning.
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