@bvitnik Hello, sm-config:vdi_type is the pre-existing one so we are still writing it for compatibility reasons. But you might notice that vdi_type is only written for LVM-based SRs. While image-format is always written in XCP-ng with the QCOW2 feature. So it might be safe to just look at image-format if it exist and if it's not, it's likely a VHD. On LVMSR, you can fallback on vdi_type (and it should work for XS too). Indeed, ISO SRs do not advertise a VDI format. Technically, ISOs could be considered to be raw. It should also be noted that our implementation of QCOW2 is very different from GFS2 QCOW2 of XenServer. Our implementation uses the existing SR types to allow VHD and QCOW2 to co-exist.

@acebmxer Yeah, it does not show up as an available device in XOA or XCP-ng Center. Just listed when running lspci

Nice detective work with iperf. I think that single-stream-versus-parallel result points at the link rather than XOA, and it matches what @Pilow saw (same CR speed on a much fatter 10 Gb path). On your multi-stream question: as far as I understand it, the transfer is a single stream per disk, which is exactly why a per-stream cap on your circuit hurts so much, though I'm honestly not certain of the internals. The one lever I'd try is NBD with multiple connections per VDI, which you can switch on under Advanced settings (https://docs.xen-orchestra.com/xo5/incremental_backups#nbd-enabled-backups); in principle, that opens several connections for the same disk, so it might get you past a single-stream limit, though I can't promise it beats your ISP's per-stream shaping. For a definitive answer on whether the data mover can parallelise per disk, it's probably one for @Team-XO-Backend. Either way, glad it's narrowed down to the link.

Maybe you can check for a bigger timeout on your UDM?

@Bryanvh No problem The issue you encountered wasn't very clear. Therefore, I've proposed a change to the XAPI to make the error more explicit (this will likely be implemented in future XAPI releases). So instead of SSL Certification failure the message will be: POOL_JOINING_MASTER_CERTIFICATE_NOT_IN_POOL_BUNDLE. Thank you very much for your patience and for bringing this issue to our attention. References: https://github.com/xapi-project/xen-api/pull/7112 LucienLassalle opened this pull request in xapi-project/xen-api closed xapi: Improve error reporting when pool join fails on TLS verification #7112