@laszlobortel since we are generating the stream sequentially, we though that there wasn't any real world gain. Also, if my understanding is correct using one thread means we will have only one process( + xo + nbdkit-vddk) processes , and we were trying to limit the risk of zombie process locking the disks , which was far too common with the previous code we'll do a quick test to ensure it does not beak anything and propose either a better default of a configuration option note that this will be a concurrency per disk, so VM with a lot of disk will put more pressure on the source

@wawa That doesn't sound right. Since you're running XOA, I would suggest contact their support to have them investigate.