Even 50GB is too small, if you are experimenting with a number of instances. The biggest growth areas are ,Cinder,Nova,block storage log files. Also consider if you are running it as a VM, then you will be running VM's inside Vm's so the performance will take a real hit.

So A running case: Image of centos 1.2GB

launched image ram 2-4GB disk ~10GB PLUS Backing files for the image 1.2GB+10gb Backing file for Swap (whatever you allocated in ram) 2-4GB

shutdown system (18GB), since a shutdown system is retained unless purged, it holds all the data & disk image allocated Yes I know all about the "thin" storage in " Cinder" BUT, what you have to consider is HOW the instance OS works. An OS assumes it is working with a "real disk" and even a thin image can fill up very quickly to its full allocated extent once you start installing other packages.Once an area in a "thin image" is allocated it CANNOT be unallocated even if empty.

Finally DON'T allow any software OS updates inside the openstack system, updates are high maintanance

I have devstack queens installed (+tacker,heat, networking-sfc, mistral) in an ubuntu16.04 VM (ubuntu18.04 host) (KVM, 4 vCPU, 10G RAM, 30G disk)

If I df the installation

df -h

Filesystem      Size  Used Avail Use% Mounted on

udev            4.8G     0  4.8G   0% /dev
tmpfs           980M   99M  881M  11% /run
/dev/sda1        32G   12G   20G  38% /
tmpfs           4.8G     0  4.8G   0% /dev/shm
tmpfs           5.0M     0  5.0M   0% /run/lock
tmpfs           4.8G     0  4.8G   0% /sys/fs/cgroup
cgmfs           100K     0  100K   0% /run/cgmanager/fs
tmpfs           980M     0  980M   0% /run/user/1001

so am using about 12G disk.

in terms of VMs here will only run 2 or 3 cirros VMs (i.e very light VM usage). Use the tiny or nano flavors.