I am going ahead  to adopt  OpensStack for  our Live deployment  sites which all are running previously on proprietary HCI solutions.

1. Which  base Operating System need to be selected for production?

 ( prefer OpenSource community Operating Systems.)  Is Debian a good choice? If so, which version ? Or any other suggestions?

2. What backend / SDS needs to be configured for a crash resistant FaultTolerant cluster. In case of a node / Disks failure which can withstand the workload and most preferably avoid data loss in the worst case scenario.

3.  Heard about Ceph. How its a best choice for a 24x7 mission critical  cluster?  kindly advise.

If so, what configuration architecture  needs to be considered ?

3.  My luxury  is only at an  On Prem Server Cluster comprising a minimum 3 to max 4 Nodes.

 ( possible DELL 650 or 750 series OR HPE servers ) .   

4.  As my cluster resources are limited to  3 to 4 server nodes / site ( 2 X32C  64 Threads, Intel Xeon Gold processors, with min 512 GB Ram , 4 x3.94TB SSD or 8 x1.92TB  in each node)

Is it reliable/advisable  to set  Controllers, Compute and Storage all together in these three or four nodes?  

Which is the best possible deployment options I can have with these 3/4 nodes.   Kindly shed some light . 

5. Any other points need to be considered  while this must be a reliable infrastructure for running a mission critical 24x7 operation. 

6.  Which mode of installation I can choose,  the Kolla-ansible  multinode is advisable for a production deployment ?  

( I am familiar with the  kolla-ansible  all-in-one installation ) OR ther a better deployment method for production sites ?  )

Kindly shed some light and your valuable suggestions . Any hints most welcome.

Thank you,

Krish