Native Ceph RBD SM driver for XCP-ng

olivierlambert

It's more like "partially"/loosely based on Alma (10, not 9). And yes, the kernel will be far more recent, same for Xen and so on.

dicode-nl

@olivierlambert I backported recent libceph/rbd/krb5 support to the xcp 8,3 kernel to support the new ceph authx aes256k method and include more rbd image features. I've added the rpms which install these newer versions as alt and extra modules and can be removed again as well. although I did run test on it I would suggest people to take caution and do not test in PROD

~~rpms removed - obsoleted~~

If anyone else is interested / has feedback please do let me know!

Kind regards
Tim

olivierlambert

Nice! Have you tested the snapshot, revert and so on?

dicode-nl

@olivierlambert busy writing/adapting de RBD SR and running tests. once I got the results and thins finalized I'll post and update with the RBDSR file (based on @benapetr)

dicode-nl

I've finished work on the RBD SR driver. Packaged as an RPM which makes sure the other kernel module drivers are required (otherwise the newer RBD features aren't available) and it doesn't require any rbd tooling on the dom0.

~~rpms removed - obsoleted~~

This needs a cephx key to have dom0 access the rbd images and a ceph mgr user/pw to manage the SR.

The driver creates a rbd namespace with the sr-uuid as it's name and the images are the vdi-uuid. so multiple sr's on the same ceph rbd pool are supported.

If leverages the xen-blkback dom0 to expose the vdi to the guest. No tapdisk, qcow2 or vhd involved. Uses native RBD snapshots, leveraging the new vdi_revert and uses GC to flatten and clean snapshots and images when required.

I'll be setting up a git repo with my sources for the kernel modules and sr driver for anyone to dive into the sources and perhaps help testing and improving this,

The next thing I'm diving into is SXM and SMAPIv3 version as I guess those are the missing parts to make this future proof.

dicode-nl

For these interested and for further development:

https://github.com/dicode-nl/xcp-ng-ceph-rbd

@olivierlambert any interest in fixing this for SMAPIv3 for inclusion into XCP 9?

benapetr

@dicode-nl hello, very nice, I will definitely check it out!

dicode-nl

@benapetr @olivierlambert I've made a new release which includes SMAPIv1 improvements and a proper SMAPIv3 volume + datapath plugin.

https://github.com/dicode-nl/xcp-ng-ceph-rbd/releases#release-v20260827

Let me know your thoughts and if there is anything you'll like to see added / changed / tested.

Next step for me is CBT and SXM.

dicode-nl

Did a lot of work this weekend and added more to the volume and datapath.
in native mode, everything is rbd native including CBT! still working on SXM
in tapdisk mode, everything is working with optimized rbd calls except SXM
in qemu mode everything works by using qemu-dp and also SXM in MSAPIv3

Huge improvements made, but qemu is the slowest mode due to extra nbt hop.
I only provided tapdisk and qemu modes to get more information on how CBT works and how SXM works. Right now I'm using that knowledge to provide SXM over native rbt. I have some good ideas but need to figure out how to make them work.

I've also made a backport to ceph v15.2 which runs on dom0 to also include the newer cephx authentication protocol. This is because the ceph dashboard cannot provide a diff between snaps (which is needed for CBT) but a pull request is pending to have this working in the future without the need for rbd userspace.

I'll update my git and packages later this week.

dicode-nl

Latest pre-release available:

https://github.com/dicode-nl/xcp-ng-ceph-rbd/releases/tag/v20260901

This release includes a qemu backend mode which fully supports SXM over SMAPIv3! Both tapdisk and native mode still don't have full SXM but can be targets to transfer VDI's to.

Also patches ceph userspace tools are available to provide rbd command line tool. This is needed for CBT as upstream Ceph doesn't have a diff end-point in their API, awaiting pull request https://github.com/ceph/ceph/pull/71388. This is already wired into the RestBackend code so once that lands in Ceph this SR can run without the need for Ceph userspace tools in dom0.

GitHub updated with the latest commits and changes.

WIP: SXM on native rbd without qemu-dp for the native and tapdisk mode.

As always, use with caution. I did run a lot of test scenario's but please do test yourself and let me know your findings!