Need to check if the max_memory value is a multiple of 256

This item is unclear. We need to figure out if the z specific requirement of >=512MB memory for a partition has impact on our host specific config option "max_memory".

The >= m512 thing is handled in bug. https://bugs.launchpad.net/nova-dpm/+bug/1689267

This bug is about if max_memory should be a multiple of 512 MB (for whatever reasons).

This bugs also tells that if value is less than 512 it should raise some exception in case there is some special parameter which rounds up to 512 needs to be verified under this bug

I found that the HMC rounds up values to certain boundaries. For example, specifying 2024 will be rounded up to 2048. I don't know whether that will happen with all input values. So if somebody is aware of a value that got rejected as invalid by the HMC, please post that to this defect.

Devstack need certain memory for its cloud i.e max_memory which is monitored and viewed in the hypervisor list in dashboard. There is filter which checks this max_memory value allows the instances to be launched on cloud ...According to my understanding this max_memory is provided in local.conf used by devstack and HMC rounding has nothing to do with this as we allocate the memory details of the partition during its creation itself.

So may be this value needs to be restricted to multiples of 512 so that max_memory parameter which restricts the maximum instances memory used efficiently

@andreas max_memory min value is 512 so may be we should change the summary and description to 512
https://github.com/openstack/nova-dpm/blob/9eceb535190b7bddedfce2bbff7bad69dec0416f/nova_dpm/conf/dpm.py#L34