[ClusterLabs] Question: Mount Monitoring for Non-shared File-system

[Asseel Sidique]

Hi Everyone,

 

I'm looking for some insight on what the best way is to configure mount monitoring for a cloned database resource.

 

Consider the resource model below:

* Clone Set: database_1-clone [database_1] (promotable):
    * Masters: [ node-1 ]
    * Slaves: [ node-2 ]
  * db2fs_node-1_Filesystem    (ocf::heartbeat:Filesystem):     Started node-1
  * db2fs_node-2_Filesystem    (ocf::heartbeat:Filesystem):     Started node-2

The database will exist on two hosts, and each database clone is dependent on the filesystem running on its corresponding
hosts. The filesystem is not shared, so I've created them as separate resources
(db2fs_node-1_Filesystem and db2fs_node-2_Filesystem).

 

The behavior I'm attempting to create is:
The cloned resource will only be able to start if the Filesystem on the same host is already started.
i.e. If the filesystem on node-1 is down, the clone database resource on node-1 will be stopped
and if the filesystem on node-2 is up, the the clone database resource on node-2 will be running

 

I've tried to set constraints for the cloned resource a few different ways:

 

1. Order constraints
order fileSystem-node-1-then-db Mandatory: db2fs_node-1_Filesystem db2_regress1_regress1_SAMPLE-clone
order fileSystem-node-2-then-db Mandatory: db2fs_node-2_Filesystem db2_regress1_regress1_SAMPLE-clone

Using these constraints, the clone database resource will stop if either filesystem resource is stopped.

 

2. Colocation constraints
colocation order-rule-Filesystem-node-1-then-db inf: db2_regress1_regress1_SAMPLE-clone:Master db2fs_node-1_Filesystem
colocation order-rule-Filesystem-node-2-then-db inf: db2_regress1_regress1_SAMPLE-clone:Slave db2fs_node-2_Filesystem

 

With these colocation constraints, if stopping one or both filesystem resources, the clone database resource looks like this:

 

* Clone Set: database_1-clone [database_1] (promotable):
    * Slaves: [ node-1 node-2 ]

Is there any advice on what the best practices to achieve this behaviour?

 

Best,

 

Asseel

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