Abstract:
Provided are techniques for comparing a first fileset associated with a first operating system (OS) with a second fileset associated with a second OS; determining, based upon the comparing, that the second OS is a more current version of the first OS; in response to the determining that the second OS is a more current version of the first OS, moving, in conjunction with live application mobility, a virtual machine (VM) workload partition (WPAR) on the first LPAR to a second LPAR, the moving comprising determining a set of overlays associated with the WPAR corresponding to the second OS; removing from the WPAR any overlays associated with the first OS; applying to the WPAR a set of overlays corresponding to the second OS; check pointing processes associated with the WAPR; and copying live data associated with the LPAR from the first LPAR to the second LPAR.

Description:
CROSS REFERENCES TO RELATED APPLICATIONS 
     The present application is a continuation and claims the benefit of the filing date of an application entitled, “Live Application Mobility From One Operating System Level To An Updated Operating System Level” Ser. No. 13/874,521, filed May 1, 2013, assigned to the assignee of the present application and herein incorporated by reference. 
    
    
     FIELD OF DISCLOSURE 
     The claimed subject matter relates generally to computing systems and, more specifically, to techniques for moving a workload partition from a logical partition with a particular operating system to a second partition with an updated version of the particular operating system. 
     BACKGROUND OF THE INVENTION 
     Unlike logical partitions LPAR s), in which computing resources are partitioned with respect to hardware, a virtualized file system is partitioned with respect to software. In addition, although LPARs which may have different operating systems, virtualized file system spaces typically include virtualized operating system (OS) environments within a single instance of an OS, an example of a virtualized file system space, used as an example throughout this Specification, is a workload partition (WPAR). It should be understood that although the claimed subject matter is described with respect to WPARs, the same principles also apply to other types of virtualized file system spaces. 
     Basically, there are two types of WPARs, system WPARs and application WPARs. Typically, a system WPAR partitions system resources and an application WPAR isolates and executes one or more application processes. The following description is based upon system WPARs. Each WPAR has a regulated share of system resources and may have unique networks and file systems. In addition, each WPAR may have separate administrative and security domains, with each WPAR having a unique root user, regular users and passwords, its own services such as inetd, cron and syslog, and can be stopped and started on its own. A WPAR does not typically share writable file systems with other WPARs or the global system. WPARs share an operating system and may share underlying file systems, real or virtual disk adapters, processors, memory, paging space and a real or virtual network card. 
     Although WPARs with in a particular LPAR share one OS, different WPARs within a LPAR may run different versions of a particular OS. Such a WPAR is called a “versioned” WPAR. A versioned WPAR typically runs an older version of an OS than the global LPAR. The versioned WPAR contains commands, shared libraries, and so on of whatever level of OS it is running. However some commands, such as, but not limited to, device drivers and other kernel extensions, within a versioned WPAR are “overlaid,” which means that the WPAR runs the corresponding command in the global LPAR. Typically, this is necessary to keep certain commands in sync with the kernel on the global LPAR because WPARs do not include their own kernel. 
     When a file is overlaid, the file is renamed, typically by adding a suffix to the name and the original file, or legacy binary, is replaced by a symbolic link to a copy of the native runtime execution wrapper. Typically, there is one copy of the native execution wrapper for each target binary&#39;s directory path. In addition, actions are taken to reflect these changes in data that an install facility use to track the state of all installed files on the system and references to the original name are replaced by the new name with the added suffix. The wrapper mechanism works as follows: 1) The path of the native library is pre-pended to the LIBPATH parameter; 2) The name of the executable that invoked the wrapper is identified; and 3) A special new “native runtime exec( ) interface” is called to execute the corresponding native binary. 
     SUMMARY 
     As the Inventors herein have realized, typically, moving a workload partition to a new logical partition requires that all running applications be stopped and restarted. Provided are techniques for moving a workload partition from a logical partition with a particular operating system to a second partition with an updated version of the particular operating system. In accordance with the disclosed technology, running programs may be moved to a more current OS without stopping and restarting, the programs. 
     Provided are techniques for comparing a first fileset associated with a first operating system (OS) with a second fileset associated with a second OS; determining, used upon the comparing, that the second OS is a more current version of the first OS; in response to the determining that the second OS is a more current version of the first OS, moving, in conjunction with live application mobility, a virtual machine (VM) workload partition (WPAR) on the first LPAR to a second LPAR, the moving comprising determining a set of overlays associated with the WPAR corresponding to the second OS; removing from the WPAR any overlays associated with the first OS; applying to the WPAR a set of overlays corresponding to the second OS; check pointing processes associated with the WAPR; and copying live data associated with the from the first LPAR to the second LPAR. 
     This summary is not intended as a comprehensive description of the claimed subject matter but, rather, is intended to provide a brief overview of some of the functionality associated therewith. Other systems, methods, functionality, features and advantages of the claimed subject matter will be or will become apparent to one with skill in the art upon examination of the following figures and detailed description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A better understanding of the claimed subject matter can be obtained when the following, detailed description of the disclosed embodiments is considered in conjunction with the following figures. 
         FIG. 1  is a block diagram of a computing system architecture that may implement the claimed subject matter. 
         FIG. 2  is a block diagram of a workload partition (WPAR) Overlay Manager (OLM), introduced above in  FIG. 1 , in greater detail. 
         FIG. 3  is a flowchart of one example of a Compare Operating Systems (OSs) process that may implement aspects of the claimed subject matter. 
         FIG. 4  is a flowchart of one example of an Evaluate Operating Systems (OSs) process that may implement aspects of the claimed subject matter. 
         FIG. 5  is a flowchart of an Apply Overlays process that may implement aspects of the claimed subject matter. 
         FIG. 6  is a flowchart of one example of an Overlay File process that may implement aspects of the claimed subject matter. 
     
    
    
     DETAILED DESCRIPTION 
     As will be appreciated by one skilled in the art, aspects of the present invention may be embodied as a system, method or computer program product. Accordingly, aspects of the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment (including firmware, resident software, micro-code, etc.) or an embodiment combining software and hardware aspects that may all generally be referred to herein as a “circuit,” “module” or “system.” Furthermore, aspects of the present invention may take the form of a computer program product embodied in one or more computer readable medium(s) having computer readable program code embodied thereon. 
     Any combination of one or more computer readable medium(s) may be utilized. The computer readable medium may be a computer readable signal medium or a computer readable storage medium. A computer readable storage medium may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples (a non-exhaustive list) of the computer readable storage medium would include the following: an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. In the context of this document, a computer readable storage medium may be any tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device. 
     A computer readable signal medium may include a propagated data signal with computer readable program code embodied therein, for example, in baseband or as part of a carrier wave. Such a propagated signal may take any of a variety of forms, including, but not limited to, electro-magnetic, optical, or any suitable combination thereof. A computer readable signal medium may be any computer readable medium that is not a computer readable storage medium and that can communicate, propagate, or transport a program for use by or in connection with an instruction execution system, apparatus, or device. 
     Program code embodied on a computer readable medium may be transmitted using any appropriate medium, including but not limited to wireless, wireline, optical fiber cable, RF, etc., or any suitable combination of the foregoing. 
     Computer program code for carrying out operations for aspects of the present invention may be written in any combination of one or more programming languages, including an object oriented programming language such as Java, Smalltalk, C++ or the like and conventional procedural programming languages, such as the “C” programming language or similar programming languages. The program code may execute entirely on the user&#39;s computer, partly on the user&#39;s computer, as a stand-alone software package, partly on the user&#39;s computer and partly on a remote computer or entirely on the remote computer or server. In the latter scenario, the remote computer may be connected to the user&#39;s computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or the connection may be made to an external computer (for example, through the Internet using an Internet Service Provider). 
     Aspects of the present invention are described below with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and/or block diagrams, and combinations of blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks. 
     These computer program instructions may also be stored in a computer readable medium that can direct a computer, other programmable data processing apparatus, or other devices to function in a particular manner, such that the instructions stored in the computer readable medium produce an article of manufacture including instructions which implement the function/act specified in the flowchart and/or block diagram block or blocks. 
     The computer program instructions may also be loaded onto a computer, other programmable data processing apparatus, or other devices to cause a series of operational actions to be performed on the computer, other programmable apparatus or other devices to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide processes for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks. It should also be understood that, although described with respect to WPARs, the claimed subject matter is equally applicable to other types of virtualized file system spaces. 
     Turning now to the figures,  FIG. 1  is a block diagram of one example of a computing system architecture  100  that may incorporate the claimed subject matter. A first computing system (CS_ 1 )  102  includes a central processing unit (CPU)  104 , coupled to a monitor  106 , a keyboard  108  and a pointing device, or “mouse,”  110 , which together facilitate human interaction with other elements of architecture  100  and computing system  102 . Also included in computing system  102  and attached to CPU  104  are computer-readable storage mediums (CRSMs), specifically a CRSM_ 1   111  and a CRSM_ 2   112 . Each of CRSMs  111 - 112  may either be incorporated into computing system  102 , i.e. an internal device, or attached externally to CPU  104  by means of various, commonly available connection devices such as but not limited to, a universal serial bus (USB) port (not shown). 
     CRSM_ 1   111  is illustrated storing two (2) logical partitions (LPARs), i.e. an LPAR_ 1   122  and an LPAR_ 2   132 . LPAR_ 1   122  is illustrated with a workload partition (WPAR), i.e., a WPAR_ 1   126 , and an operating system (OS), i.e. OS_ 1   124 . WPAR_ 1   126  includes a overlaid file system, i.e. an OLFS_ 1   128  LPAR_ 2   132  is illustrated with an operating system, OS_ 2   134 . In the following examples, OS_ 1   124  is an older version of OS_ 2   134 . Also stored on CRSM_ 1   111  for execution on one or more processors (not shown) of computing system  102  is an WPAR Overlay Manager (OLM)  136 . In the following examples, WPAR OLM  136  is configured to implement the claimed subject matter. 
     CS_ 1   102  is coupled to a local area network (LAN)  140 , which provided connectivity among a server computer, or simply “servcr,”  142 , a storage area network (SAN)  144  and a second computing system (CS_ 2 )  146 . Although in this example, computing system  102 , server  142 , SAN  144  and CS_ 2   146  are communicatively coupled via LAN  140 , they could also be coupled through any number of communication mediums such as, but not limited to, direct connections, a wide area network (WAN) and the Internet (none of which are shown). Like CS_ 1   102 , CS_ 2   146  includes a CPU, i.e. CPU  148 , and a CRSM, i.e., CRSM  150 . CRSM  150  is illustrating storing a logical partition, i.e., LPAR_ 3   152 , which includes and an operating system, i.e., OS_ 3   154 , and a WPAR OLM, i.e., WPAR OLM  156 . Although not shown for the sake of simplicity, CS_ 2   146  would typically include a monitor, a keyboard and a mouse. Like OS_ 2   134 , OS_ 3   154  is a more current version of operating system than OS_ 1   124 . In the following examples, the disclosed technology describes how WPAR_ 1   126  may be migrated from LPAR_ 1   122  and OS_ 1   124  on CS_ 1   102  to LPAR_ 3   152  and OS_ 3   154  on CS_ 2   146  (see  200 ,  FIG. 3, 240 ,  FIG. 4, 270 ,  FIG. 5 and 300 ,  FIG. 6 ). As explained above, WPAR_ 1   126 , once migrated, is a versioned WPARs, i.e., running a less current version of an OS than the LPAR on which it is installed. 
     Computing devices  142  and  144  are used as examples of resources that may be available to computing system  102  and serve as potential access points and storage devices for computing system  102 . It should be understood that although illustrated only on two computing systems and CRSMs, LPARs  122 ,  132  and  154 . WPAR  126  and WPAR OLMs  136  and  156  may reside on different CRSMs and even different computing systems such as CRSMs  112  and  113 , server  142  and CS_ 2   146 . It also should be noted that typical architectures and computing system would typically include many addition elements, but for the sake of simplicity only a few are shown. 
       FIG. 2  is a block diagram of WPAR OLM  136 , introduced above in  FIG. 1 , in greater detail. WPAR OLM  136  includes an input/output (I/O) module  160 , a data module  162 , an OS evaluation module  164 , an overlay module  166  and operation logic  168 . Although there may be other components of WPAR OLM  136 , for the sake of simplicity, only components  160 ,  162 ,  164 ,  166  and  168  are illustrated and described. For the sake of the following examples, logic associated with WPAR OLMs  136  and  156  are assumed to execute on one or more processors (not shown) of computing systems  102  and  146  ( FIG. 1 ), respectively, and to be stored an CRSMs  111  and  150  ( FIG. 1 ), respectively. It should be understood that the claimed subject matter can be implemented in many types of computing systems and data storage structures but, for the sake of simplicity, is described only in terms of CS_ 1   102  ( FIG. 1 ), CS_ 2   146  and system architecture  100  ( FIG. 1 ). Further, the representation of WPAR OLM  136  in  FIG. 2  is a logical model. In other words, components  160 ,  162 ,  164 ,  166  and  168  may be stored in the same or separates files and loaded and/or executed within computing system  102  and architecture  109  either as a single system or as separate processes interacting via any available inter process communication (IPC) techniques. 
     I/O module  160  handles any communication WPAR OLM  136  has with other components of computing system  102 , architecture  190  and any administrator or user. Data module  162  is a data repository for information and parameters that WPAR OLM  136  requires during operation. Examples of the types of information stored in data module  162  include system data  170 , LPAR data  172 , WPAR data  174 , version data  176 , fileset data  178  and option data  180 . 
     System data  170  stores information relating to other elements of architecture  100 , such as but not limited to, server  142  ( FIG. 1 ), SAN  144  ( FIG. 1 ) and CS_ 2   146  ( FIG. 1 ). In short, system data  160  stores information that enables, among other things, WPAR OLE  136  to communicate with WPAR OLE  156  executing on CS_ 2   146  to implement aspects of the claimed subject matter. LPAR data  172  stores information relating to established LPARs such as LPAR_ 1   122  ( FIG. 1 ) and LPAR_ 2   132  ( FIG. 1 ), including, but not limited to, information on the particular OS running on each. WPAR data  174  stores information relating to established WPARs such as WPAR  122 , including, but not limited to, various resources that may be allocated to WPAR  126 . Version data  176  stores information on the specific version of OSs  124  and  134  that each of LPARs  132  and  122  is currently executing. Fileset data  178  stores information about the filesets installed in each of WPAR  126  as well as the specific filesets that have been overlaid in accordance with the claimed subject matter. Option data  180  stores user and administrative operating parameters that may control the operation of WPAR OLM  136 . 
     OS evaluation module  164  is associated with logic for comparing operating system such as OSs  124 ,  134  and  154  are earlier, the same or more current versions of each other (see  240 ,  FIG. 4 ). Overlay module  166  stores logic responsible for installing the appropriate filesets in versioned WPARs such as WPARs  126  and  134  in accordance with the claimed subject matter. Operation logic  168  stores logic associated with implementation of the claimed subject matter as well as logic responsible for the typical logic associated with the installation and updating of WPARs such as WPARs  126  and  127 . Components  152 ,  154 ,  156 ,  160 ,  162 ,  164 ,  166  and  168 , which would have corresponding structures in WPAR OLM  156  ( FIG. 1 ) are described in more detail below in conjunction with  FIGS. 3-6 . 
       FIG. 3  is a flowchart of one example of a Move WPAR process  200  that may implement aspects of the claimed subject matter. In this example, process  200  is associated with logic stored on CRSM_ 1   111  ( FIG. 1 ) in conjunction with WPAR OLM  136  ( FIGS. 1 and 2 ) and executed on one or more processors (not shown) of CPU  104  ( FIG. 1 ) of computing system  102  ( FIG. 1 ). In the following example, WPAR_ 1   126  ( FIG. 1 ) is moved from LPAR_ 1   122  ( FIG. 1 ), which is referred to as the “departure” LPAR and is running on OS_ 1   124  ( FIG. 1 ), to LPAR_ 3   152  ( FIG. 1 ) on CS_ 2   146  ( FIG. 1 ), which referred to as the “arrival” LPAR and is running OS_ 3   154  ( FIG. 1 ), a more current version OS than OS_ 1   124 . 
     Process  200  begins in a “Begin Move WPAR” block  202  and proceeds immediately to an “Evaluate OSs” block  204 . During processing associated with block  204 , a determination is made as to the specific versions of the OS_ 1   124 , from which WPAR_ 1   126  is being moved, and OS_ 3   154 , to which WPAR_ 1   126  is being moved (see  240 ,  FIG. 4 ). Such a determination may be based upon information stored in conjunction with WPAR OLM  136  (see  162 ,  FIG. 2 ) and a comparison of filesets that are typically installed in specific operating systems (see  240 ,  FIG. 4 ). During processing associated with a “To Same OS?” block  206 , a determination is made as to whether or not OS_ 3   154  is the same version as OS_ 1   124 . If not, control proceeds to a “To Newer OS?” block  208 . During processing associated with block  208 , a determination is made as to whether or not OS_ 3   154  is a more current version of OS_ 1   124 . If not, control proceeds to a “Throw Exception” block  210 . The disclosed techniques apply to moving a WPAR of a newer OS so during processing associated with block  210  actions are taken to notify the user or administrator that the move is not being implemented. 
     If, during processing associated with block  298 , a determination is made that OS_ 3   154  is a more current version of OS_ 1   124 , control proceeds to an “Apply Overlays” block  212 . During processing associated with block  212 , OLFS  128  ( FIG. 1 ) is generated and added to WPAR_ 1   126  (see  270 ,  FIG. 5 ). In short, during processing associated with block  212 , files, registers and parameters associated with WPAR_ 1   126 , including any files that have been overlaid, are migrated to LPAR_ 3   152  in accordance with know or yet to be developed migration procedures, typically via LAN  140 . 
     During processing associated with a “Checkpoint Processes” block  214 , all running processes within WPAR_ 1   126  are halted in anticipation of the move. While hatted, application data such as open files, memory content and so on are captured and transferred to the arrival LPAR. This provides a window of opportunity when none of the processes of the WPAR are running, thus the overlays and update may take place because there is no current updating of software vital product data (SWVPD). File systems of the WPAR are still accessible from the departure side so overlays can be applied during this time period. Essentially, the timing enables overlays to be applied in an atomic manner relative to any other activity on the system. 
     During processing associated with a “Move WPAR” block  216 . WPAR_ 1   126  is copied from LPAR_ 1   122  and CS_ 1   102  to LPAR_ 3   152  and CS_ 2   146 . In short, live data associated with WPAR_ 1   126  is captured in LPAR_ 1   122  and transferred to LAPR_ 3   152  via LAN  140 . In this example, files associated with WPAR_ 1   126  reside on SAN  144 , which is shared by CS_ 1   102  and CS_ 2   146 , and are accessed by LPAR_ 3   152  as they were by LPAR_ 1   122  before the move. During processing associated with a “Restart Processes” block  218 , all processes of WPAR  126  that were halted during processing associated with block  214  are restarted and WPAR_ 1   126  is up and running on LPAR_ 3   152  and CS_ 2   146 . Once processes have been restarted on the arrival side and begin accessing the file systems, OLFS  128  is in place during processing associated with a “Finish Move WPAR” block  214 . Finally, control proceeds to an “End Move WPAR” block  229  in which process  200  is complete. 
       FIG. 4  is a flowchart of an “Evaluate OSs” process  240 . In this example, process  240  is associated with logic stored on CRSM  112  ( FIG. 1 ) in conjunction with WPAR OLM  136  ( FIGS. 1 and 2 ) and may involve communication between WPAR. OLM  136  and WPAR OLM  156  on CS_ 2   146 . Although some information on an OS may be obtained from a query to the OS, the detail is typically not sufficient to support the claimed subject matter. For example, AIX systems provide a “ostype” attribute that indicates the AIX level of the runtime provided to applications. 
     Process  249  starts in a “Begin Evaluate OSs” block  242  and proceeds immediately to an “Identify Filesets” block  244 . During processing associated with block  244 , a defined, core group of AIX filesets that are typically installed with an OS, and/or have some impact on the environment are identified within OS_ 1   124  and OS_ 3   154  (see  166  and  168 .  FIG. 2 . During, processing associated with a “Check install Levels” block  246 , the filesets identified during processing associated with block  244  are checked to determine their various properties. During processing associated with an “Install Levels (ILs) Match” block  248 , a determination is made as to whether or not the filesets in OS_ 1   124  and OS_ 3   154  match. 
     If so, control proceeds to a “Return Match” block  250  and the process that called process  240  (see  206 ,  FIG. 3 ) is notified that the OSs are the same. If not, control proceeds to a “Correlate to OSs” block  252  during the filesets identified during processing associated with block  244  for each OS are correlated to determine a specific OS level. During processing associated with a “Return OS Levels” block  254 , the OS levels determined during processing associated with block  254  are returned to the calling process. Finally, during processing associated with an “End Evaluate OSs” block  259 , process  240  is complete. 
       FIG. 5  is a flowchart of one example of an “Apply Overlays” process  270  that may implement aspects of the claimed subject matter. Process  270  corresponds to Apply Overlays block  216  ( FIG. 3 ) of Move WPAR process  200  ( FIG. 3 ). Like process  200 , in this example, process  270  is associated with logic stored on CRSM_ 1   111  ( FIG. 1 ) in conjunction with WPAR OLM  136  ( FIG. 1 ) and executed on one or more processors (not shown) of CPU  104  ( FIG. 1 ) of computing system  102  ( FIG. 1 ). 
     Process  270  begins in a “Begin Apply Overlays” block  272  and proceeds immediately to a “Determine OSs” block  274 . During processing associated with block  274 , the OS of the arrival LPAR, which in this example is OS_ 3   154  of LPAR_ 3   154 , is ascertained, typically based upon stored information (see  160 ,  FIG. 2 ) and information gathered by comparing various fileset levels in OSs  124  and  154  (see  240 ,  FIG. 4 ). During processing, associated with an “Overlays (OLs) Needed?” block  276  a determination is made as to whether or not overlays are needed for the current move. If so, control proceeds to a “Retrieve OL Info” block  278  during which information that lists the specific overlay required is gathered. Typically, this information is stored in conjunction with WPAR OLM  136  (see  160 ,  162 ,  164 ,  166  and  168 ,  FIG. 2 ). During processing associated with a “Remove Overlays” block  280 , old overlays are removed. 
     During processing associated with a “Get Next File in OL List” block  282 , the name of a file yet to be processed is selected from the OL info retrieved during processing associated with block  278 . During processing associated with an “Overlay Files” block  284 , the file whose name was selected during processing associated with block  282  is overlaid (see  300 ,  FIG. 6 ). During processing associated with a “More Files?” block  286 , a determination is made as to whether or not there are files listed in the info retrieved during processing associated with block  278  that have yet to be processed. If so, control returns to block  282 , the next name in the list is selected and processing continues as described above. If not, or if a determination has been made during processing associated with block  276  that overlays were not needed, control proceeds to an “End Apply Overlays” block  289  during which process  270  is complete. 
       FIG. 6  is a flowchart of one example of an Overlay File process  300  that may implement aspects of the claimed subject matter. Process  300  corresponds to Overlay File block  284  ( FIG. 5 ) of Apply Overlays process  270  ( FIG. 5 ). Like processes  200 ,  240  and  270 , in this example, process  300  is associated with logic, stored on CRSM_ 1   111  ( FIG. 1 ) in conjunction with WPAR OLM  136  ( FIG. 1 ) and executed on one or more processors (not shown) of CPU  104  ( FIG. 1 ) of computing system  102  ( FIG. 1 ). 
     Process  300  begins in a “Begin Overlay File” block  302  and proceeds immediately to a “Fileset (FS) Present?” block  304 . During processing associated with block  304 , a determination is made as to whether or not the file being processed (see  260 ,  FIG. 4 ) is a member of a fileset that is already present in the WPAR being processed. As explained above, in formation on the files of the WPAR (see  162  and  166 ,  FIG. 2 ) includes the fileset to which the file belongs. It should also be noted that, although not illustrated in this particular diagram, if a particular file is not present and not part of a mandatory fileset, the file is not needed and therefore no overlay is created. 
     If the fileset is present, control proceeds to a “Save Original File” block  306 . During processing associated with block  306 , the file that is already installed is renamed, typically by adding a suffix to the original name. In addition, references to the file in any files that track the file for administrative purposes are also modified to reflect the new name so that, when the original file is to be updated, the original file is updated rather than the file identified by the link. If, during processing associated with block  304  a determination is made that the fileset to which the file belongs is not present, control proceeds to an “FS Mandatory?” block  308 . During processing associated with block  308 , a determination is made as to whether or not the fileset that was determined not to be present during processing associated with block  304  is a required fileset. If so, or if during processing associated with block  306  the original file has been saved under a new name, control proceeds to a “File Binary?” block  310 . During processing associated with block  310 , a determination is made as to whether or not the file being processed is binary or not, i.e. a script file. If the file is binary, control proceeds to a “Create Link to Runtime Execution Wrapper (RTEW)” block  312 . During processing associated with block  312 , a link to the RTEW is generated, having the original name of the file. If a determination is made, during processing associated with block  310 , that the file being processed in not binary, then control proceeds to “Create Link to Global Script File (GSF)?” block  314 . During processing associated with block  314 , a link is created to the corresponding global script file. It should be noted that a script file does not need to employ a RTEW so the link points directly to the corresponding GSF of the native OS. 
     In addition, if a determination was made during, processing associated with block  304 , that the file was not present and during processing associated with block  308  that the file was not mandatory, then the original file did not need to be renamed because the file was not installed. In this manner, files that do not need to be installed and will never be used are not installed and do not consume computing resources. 
     Once a either link to a RTEW has been created during processing associated with block  312  or a link to a GSF created during block  314 , control proceeds to an “End Generate Overlay” block  319  during which process  300  is complete. Files handled in accordance with the disclosed technology eliminate work WPAR OLM  136  would typically need to perform because original files are not installed and thus do not need to be overlaid during updates. Concerns that overlaid files are over-written are also eliminated. In addition, any updates to files in the LPAR_ 2   132  are automatically applied because the WPAR_ 1   126  will point to the updated binaries and scripts as soon as they are placed in the LPAR_ 2   132 . 
     The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a”, “an” and the are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. 
     The corresponding structures, materials, acts, and equivalents of all means or step plus function elements in the claims below are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed. The description of the present invention has been presented fir purposes of illustration and description, but is not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the an without departing from the scope and spirit of the invention. The embodiment was chosen and described in order to best explain the principles of the invention and the practical application, and to enable others of ordinary skill in the art to understand the invention for various embodiments with various modifications as are suited to the particular use contemplated. 
     The flowchart and block diagrams in the Figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods and computer program products according to various embodiments of the present invention. In this regard, each block in the flowchart or block diagrams may represent as module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). It should also be noted that, in some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems that perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.