Oracle RAC Processes

GSD global services daemon (GSD)

 

Dbca srvctl, a management tool for RAC
The OEM interacts with each other to complete management tasks such as instance startup and shutdown.
To ensure that these management tools run normally, you must start them on all nodes.
GSD, and a GSD process supports
Multiple RAC. GSD processes of a node are located in the $ ORACLE_HOME/bin directory, and their log files
$ ORACLE_HOME
/Srvm/log/gsdaemon. Log
For example:
Assume that you use an OEM tool to start an instance.
The task is passed to the corresponding Intelligent engine, which generates
A script file containing the srvctl command. The GSD process reads the script file and runs the script.
Executive
Rows of results are returned to the intelligent engine, while the Intelligent engine returns to the OEM.
For example, if you use the srvctl tool to close all instances, the GSD process accepts requests from the srvctl tool.
And
Execute the request on the local node and return the execution result to the srvctl session.

 

 

Lmon: Global enqueue Service
Monitorlmon

 

It monitors global queues and global resources in a cluster, manages instances, handles exceptions, and recovers corresponding cluster queues.

 

 

LMD: Global
Enqueue service daemonlmd Process

 

It mainly manages access to global queues and resources, updates the status of corresponding queues, and Processes requests from other instances.
Please
. The current status of each global queue is stored in the shared memory of the corresponding instance.
You have the right to use the resource. Shared Memory of one instance (master)
In a special queue, this queue
Record the resource requests from other remote instances. When the LMD process of the remote instance sends a resource request, this request
Point to the master instance
LMD: When the lmd process of the master instance receives this request, a special queue in the shared memory
Monitor whether the resource is invalid. If the resource is valid, the LMD process updates the status of the resource pair column.
Status, and notifies the requested resource
The LMD process can be used by this resource queue. If the resource queue is being used by another instance or is currently invalid
LMD process notifies an instance in use
The lmd process of should release the resource. When the resource release becomes effective,
The lmd process of the master instance updates the status of the resource queue and notifies the LMD process of the requested resource instance of this resource.
Team
The column can be used. In addition, the LMD process is also responsible for the deadlock issue in the queue...

 

 

Lmsn: Global cache service process (n
0 ~ 9)

 

The LMS process is mainly used to manage access to data blocks in the cluster and transmit blocks in the buffer cache of different instances.
Image. The LMS Process manages databases across clusters,
And ensure that one of the buffer caches of all instances
Data block images can only appear once. The LMS process coordinates the access of data blocks by passing messages in the instance. When
I
When the instance requests data blocks, the LMD process of the Instance sends a data block resource request.
Master data block instance LMD process, Master instance LMD
LMD of the instance that the process is using at the same time
When the process releases the resource, the LMS process of the instance that owns the resource will create a consistent read of the data block image.
Then pass the data block
The buffer cache of the Instance requesting the resource.
The LMS process ensures that only one instance can be allowed to update a data block at a time, and maintains
Image history
Records (including the status flag of the updated data block), RAC provides 10 LMS processes, the number of processes
The amount of data transmitted between nodes increases.

 

 

LCK

 

Processes are mainly used to manage resource requests between instances and cross-instance call operations. Call operations include data dictionary and other objects.
And handle the caceh
Fusion's Chace resource request (for example, Dictionary cache)

 

 

Diag: diagnosability
Daemondiag Process

 

It is mainly used to capture the diagnostic information of failed processes in the instance and generate the corresponding trace file (the trace
Save the file in
Backupground_dump_dest/cdmp_timestamp directory), the process does not
Configuration is not recommended. The process cannot be started automatically.
It needs to be adjusted. If the process fails, it will automatically
Restart.