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In Openstack, is it possible to create compute nodes with no hard drives and use PXE in order to boot the host's system and therefore launch instances with no local drive which is needed to boot the VM's image.

If not what's the minimum storage needed to be given to hosts in order to get fully functional system.

Rafik
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    Of course this is possible. – Gerald Schneider Oct 15 '21 at 11:14
  • @GeraldSchneider according to the Openstack documentation, "The Image service copies the base image from the image store to the local disk. " "he instance boots up from root volume vda. " and vda refers to the local disk which is the host's disk, so how can I boot instances if there is no disk available – Rafik Oct 15 '21 at 11:48
  • What do you mean under local drive? Do you want to spin up VMs that have 0 storage? All just running off of RAM? Or you want to run a VM with a remote disk? You can mount a remote disk to openstack and use that as the VMs local storage. – Barnabas Busa Oct 15 '21 at 11:56
  • @BarnabasBusa I want to use remote disks and leave hosts with no disks, and I would boot the hosts using PXE and then use remote disks in order to boot the Vm instances, this would leave me with a running instance on a server that doesn't have any local storage. what I want to know is if this is possible, and if it wouldn't effect the performance of my VMs. – Rafik Oct 15 '21 at 12:00
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    Openstack does not care what that`local drive` is. It doesn't even know what it is. It can be a hard disk, SSD, USB thumb drive, floppy disk, ram drive, NFS mount ... whatever you have. – Gerald Schneider Oct 15 '21 at 12:01

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You can have a host with no disk. You can use this host to be your main openstack server. It is possible to mount remote shares to this server for persistent storage. An example for such a configuration would be a remote NFS share as your backend.

Having remote servers allow much simpler and cheaper scalability, as this way you can have bulk disk servers and bulk compute nodes.

In order to ensure that you have no performance degregation, sufficient backbone network infrastructure is needed. (At least a 10Gbps network!)

Barnabas Busa
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