Ceph pool vs rbd
- Thread starter cardax
- Start date
Not sure if I understand your question.
You create a pool. A pool is like a logical partition with rules (for example number of replicas).
It will be accessed with RBD (librbd or the krbd kernel module). RBD will create block devices for the VM disks in that pool.
RBD is used for VM disks because it is a (RADOS) Block Device, so it doesn't have the overhead of an extra filesystem.
See also:
https://docs.ceph.com/en/reef/rbd/
https://docs.ceph.com/en/reef/rados/operations/pools/
You create a pool. A pool is like a logical partition with rules (for example number of replicas).
It will be accessed with RBD (librbd or the krbd kernel module). RBD will create block devices for the VM disks in that pool.
RBD is used for VM disks because it is a (RADOS) Block Device, so it doesn't have the overhead of an extra filesystem.
See also:
https://docs.ceph.com/en/reef/rbd/
https://docs.ceph.com/en/reef/rados/operations/pools/
For PVE to use any storage type you need 2 things:
- A storage backend, which in this case is the Ceph Pool.
- A logical entity created at Datacenter, Storage that relates to a storage backend. In this case is the RBD type storage that is related to each Ceph pool.
So you need both the Ceph Pool and the RBD type storage in PVE to store your VMs in Ceph.
- A storage backend, which in this case is the Ceph Pool.
- A logical entity created at Datacenter, Storage that relates to a storage backend. In this case is the RBD type storage that is related to each Ceph pool.
So you need both the Ceph Pool and the RBD type storage in PVE to store your VMs in Ceph.
Sorry @VictorSTS , but it’s not like that. Once the pool is created without adding any type of storage, I can create VMs and disks directly in the pool. So my question again. What is the difference between a pool and an RBD storage?"
where you create the pool, they are an option to directly add it as storage with same name than the pool (in /etc/pve/storage.cfg).
It's just a shortcut, you can do it manually if you want. (create a rbd storage using the pool).
tks you are right.
easy exmplanation
Add during pool creation.
rbd: pool01
content images,rootdir
krbd 0
pool pool01
Add from storage task:
rbd: rbd01
content images
krbd 0
pool pool01
Maybe as a more general explanation: whatever you have in Datacenter -> Storage (
As @spirit mentioned, when managing the storage layer through Proxmox VE, you usually have the "Add Storage" checkbox that will create a matching storage config for you. For example, in Ceph, but also if you create a local storage under {Node}->Disks->{LVM/ZFS/...}
/etc/pve/storage.cfg) are the storages Proxmox VE knows about. They don't have a direct result on the actual storage layer, but rather make sure the nodes can connect to that said storage.As @spirit mentioned, when managing the storage layer through Proxmox VE, you usually have the "Add Storage" checkbox that will create a matching storage config for you. For example, in Ceph, but also if you create a local storage under {Node}->Disks->{LVM/ZFS/...}