On Wed, Mar 05, 2025 at 03:36:35PM +0530, prashant patil wrote: > I was trying to read the bitmap of the running vm's disk. When I followed > below mentioned commands, then I was able to read the bitmap properly. > block-dirty-bitmap-add, block-dirty-bitmap-disable, nbd-server-start, > nbd-server-add,
Up to here, everything you've done is indeed the ideal way to get at the contents of a bitmap from a live qemu process over an NBD connection. > qemu-img > map with x-dirty-bitmap image-opts. Here, this works, but feels like a hack, because it is relying on the x-dirty-bitmap feature of qemu. The libnbd project ships with an application 'nbdinfo --map' that can read the same information as 'qemu-img map' but with a much nicer layout. It's not going to necessarily be faster, but because it is a fully-supported feature of libnbd rather than a hack in qemu, it may prove more stable in the long run, and certainly easier to understand. -- Eric Blake, Principal Software Engineer Red Hat, Inc. Virtualization: qemu.org | libguestfs.org
