Questions related to Piraeus usage

[piraeusdatastore]

Questions related to Piraeus usage

[WanzenBug]

Re Question 1: I'm not an expert in Proxmox, but essentially, your VMs will only see a generic block device. They don't see anything "outside", so they also cannot interfere with the "outer" LVM (thin) metadata. So there is nothing to "support" from Piraeus/LINSTOR side, it's just as if you attached an actual disk.

Re Question 2: In short: that is not possible. Longer answer: Fundamentally, LINSTOR creates block storage of some kind. For example that can be a LVM Thin Volume, a ZVOL, ... Piraeus can then automatically create a filesystem on that volume so it can be used as a filesystem volume in Kubernetes.

As for the workaround: It could work, but was never tested. It would introduce another layer that may impact performance. Instead of directly reading and writing to the device, you first have to go through loopdev -> filesystem -> disk. So while it could work (LINSTOR even has a storage driver based on files, which uses loopdev internally), I would no recommend it and there is no documentation for it.

Question 3: The operator will not create any storage classes. You can create the LINSTOR storage pools via the operator, then generate your own storage classes using the storage pools. For example:

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: three-replicas
provisioner: linstor.csi.linbit.com
allowVolumeExpansion: true
parameters:
  autoPlace: "3"
  storagePool: $MYPOOL
  resourceGroup: three-replicas

[immanuelfodor]

Thank you for taking the time to answer, very helpful and clear explanation. I'll choose the separate disk (sdb) route then.

If I ever want to increase the available disk size (e.g., starting with 8G then increasing it to 16G, not a bound PV resize but what is available for the StorageClass to schedule), could I simply do it outside on the host without the knowledge of Linstor (resizing the disk and then extending LVM Thin), or should I do the LVM operation with the Linstor CLI? For example set-size seems related but I'm not that familiar of the CLI's capabilities (yet):

root@piraeus-op-cs-controller-7fb6c98656-zvx49:/# linstor volume-definition
usage: linstor volume-definition [-h]
                                 {create, delete, drbd-options, list,
                                 list-properties, set-property, set-size} ...
linstor volume-definition: error: too few arguments

[WanzenBug]

Resize should happen on the host. Basically:

$ pvscan --cache # optional, depending on if the host uses lvmetad
$ pvresize /dev/sdb
  Physical volume "/dev/sdb" changed
  1 physical volume(s) resized or updated / 0 physical volume(s) not resized
$ lvextend /dev/linstor_pool/pool /dev/sdb

[immanuelfodor]

Superb, thank you! Closing this issue for now as I got all the answers that were not obvious from the existing guides. In the meantime, I managed to create and attach the new disks to the VMs, configured the satellite storagePool, Piraeus deployment works fine, just about to create the storage class and provision some volumes to pods. Exciting times ahead :)