On 04/04/2016 05:15 PM, Eric Blake wrote: > qemu already has an existing server implementation option that will > explicitly search the payload of NBD_CMD_WRITE for large blocks of > zeroes, and punch holes in the underlying file. For old clients > that don't know how to use the new NBD_CMD_WRITE_ZEROES, this is a > workaround to keep the server's destination file approximately as > sparse as the client's source. However, for new clients that know > how to explicitly request holes, it is unnecessary overhead; and > can lead to the server punching a hole and risking fragmentation or > future ENOSPC even when the client explicitly wanted to write > zeroes rather than a hole. So it makes sense to let the new > NBD_CMD_FLAG_NO_HOLE work for WRITE as well as WRITE_ZEROES. > > Signed-off-by: Eric Blake <[email protected]>
what behaviour do you expect for QCOW2 file? We should fully provision that image as far as I could understand, i.e. allocate data blocks with zero content. I think that this would work. ------------------------------------------------------------------------------ _______________________________________________ Nbd-general mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/nbd-general
