Could I export rbd device to meta-device

[fengren]

Now, I can use deltaic to backup my rbd device to filesystem very well. But, when I export rbd device to iscsi device or loop device on my system which is running centos7.2, it will destroy the target device with cost most cache/buffer of memory. With:IOError: [Errno 28] No space left on device. And I can't find the target device until re-login or losetup again. So, I want to know is deltaic supported to backup rbd device to meta-device currently?

[jaharkes]

deltaic only backs up to a filesystem on a thin-provisioned lvm volume. If you want to copy the content of a rados block device (rdb) directly to an iscsi or loopback device you should be able to use the rbd tool from Ceph to export the raw image and probably dd to write to the device, something like rbd export <image-name> - | dd of=/dev/iscsidevice.