(1) The current contents of memory, which includes the operating system and running programs. For effective management, a cluster of computer systems may be organized as a single system image, in which all systems appear as one. See
virtual server and
Sysplex.
(2) The current contents of the hard disk, which includes the operating system and installed applications. Copying system images from one computer to another is the fastest way to populate new hardware, because copying pre-installed applications is much faster than installing them. See
disk image,
virtual appliance and
install program.