In block storage metadata is kept in the "metadata" logical volume.
To find metadata for particular volume, you need to to look at the logical volume tags:
lvs -o tags vg-name/lv-name
Which will output tags like MD_42
The metadata for this volume is at slot number 42.
To find the metadata, you need to calculate the offset in the metadata logical volume.
On storage domain V4 format, the offset is:
offset=$((42 * 512))
On storage domain V5 format, the offset is:
offset=$((1048576 + 42 * 8192))
You can read the metadata like this:
dd if=/dev/vg-name/metadata bs=512 count=1 skip=$offset conv=skip_bytes iflag=direct