[Pacemaker] How does ptest work?

[Andrew Beekhof]

On Jan 2, 2008, at 10:36 PM, Michael Schwartzkopff wrote:

> (...)
>>> How does ptest know what I changed in my CIB? I checked that it does
>>> NOT
>>> compare it to the running CIB, and the IP address is not noted in  
>>> the
>>> status section of the CIB. So how does ptest the job?
>>
>> in the status section you'll find a whole lot of lrm_rsc_op  
>> "objects" ^
>> these represent a cluster operation and includes a number of fields
>> that help us determine which order they were performed in and what
>> parameters where used.
>>
>> in particular, there is a field called "op_digest" which we use to
>> detect changes to the resource's parameters
>
> So this fields contain some hash of the configuration at the last  
> change. If
> the hash changes ptest can find out what changed and do the nescessary
> transitions. Am I right here?

mostly - it knows something changed, but not which specific field