VSZ
also: Virtual Memory Size, VIRT
VSZ (Virtual Memory Size) is the total amount of virtual memory allocated to a process, including all memory regions whether currently in physical RAM or swapped to disk.
VSZ represents the complete virtual address space claimed by a process. This includes executable code, libraries, heap, stack, and memory-mapped files—regardless of whether that memory is actually resident in RAM at any given moment.
You can see VSZ in the output of commands like ps and top. For example, running ps aux shows VSZ in the fifth column. A process might have a VSZ of 500 MB but only 50 MB actually in physical RAM (shown as RSS), with the rest either unused or swapped out.
VSZ is useful for understanding a process's total memory footprint and potential resource consumption, though RSS (Resident Set Size) is often more relevant for gauging actual memory pressure on the system.