@zorro So with purge off, Veeam stayed clean for a few nights, which fits what I saw in the lab test.
If I read the docs right, the cost is that XO's reference snapshot keeps its data on the SR again, which you'd notice more on thick-provisioned storage: https://docs.xen-orchestra.com/backups-and-dr/backup-types/incremental_backups#purge-snapshot-data-cbt.
Storage hasn't said yet whether purge breaking another tool's chain is expected, so I'd still call this a workaround rather than the answer.
If a CBT warning comes back when you add the other VMs, the Veeam task id and the time would probably help them. And keeping both makes sense to me, since Veeam doesn't do the cross-site replication you need XO for.
