OpenEBS have three storage Engines, Jiva, cStor and LocalPV which can be used to provision OpenEBS volumes.
Jiva requires the disk to be mounted (i.e., attached, formatted with a filesystem and mounted).
The application can be provisioned using OpenEBS Local PV based on the device. For provisioning OpenEBS Local PV using the block devices attached to the nodes, the block devices should be in one of the following states.
- User has attached the block device, formatted and mounted them.
- For Example Local SSD in GKE.
- User has attached the block device, un-formatted and not mounted them.
- For Example GPD in GKE.
- User has attached the block device, but the device has only device path and no dev links.
- For Example VM with VMDK disks or AWS node with EBS
cStor can consume disks that are attached (are visible to OS as SCSI devices) to the Nodes which does not have any filesystem and it should be unmounted on the Node. It is recommended to wipe out the disk if it was previously used.
In case you need to use Local SSDs as block devices for provisioning cStor volume, you will have to first unmount them and remove any the filesystem if it has. On GKE, the Local SSDs are formatted with ext4 and mounted under "/mnt/disks/". If local SSDs are mounted and contains any file system, then cStor pool creation will fail.