HDR_FULL_SIZE
bzero(hdr, HDR_FULL_SIZE);
arc_space_consume(HDR_FULL_SIZE, ARC_SPACE_HDRS);
arc_space_return(HDR_FULL_SIZE, ARC_SPACE_HDRS);
hdr_full_cache = kmem_cache_create("arc_buf_hdr_t_full", HDR_FULL_SIZE,