1. A system comprising: a central processing unit (CPU) of a node coupled to one or more storage devices; and a memory coupled to the CPU and configured to store a storage input/output (I/O) stack having a volume layer executable by the CPU, the volume layer configured to manage volume metadata embodied as mappings from offsets of a logical unit (LUN) to extent keys associated with storage locations for extents on the one or more storage devices, the volume layer further configured to organize the volume metadata as a dense tree metadata structure representing successive points in time to enable access to the volume metadata, the dense tree metadata structure organized as multiple levels, wherein a top level of the dense tree metadata structure represents newer volume metadata changes and descending levels of the dense tree metadata structure represent older volume metadata changes, wherein a latest version of changes to the volume metadata is searched from the top level to the descending levels, wherein the top level is merged with one or more of the descending levels at the successive points in time, and wherein each of the merged descending levels of the dense tree metadata structure is maintained on the storage devices as a packed array of volume metadata entries sorted by offset of the LUN.