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

[Andrei Borzenkov]

On 07.12.2021 21:35, Asseel Sidique wrote:
> 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

The resource name in these constraints does not match clone name you show earlier.

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

Try setting interleave=true for clone.

> 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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