Patent Application
20050022200
1. Technical Field
This invention generally relates to data processing, and more specifically relates to detection of resources in a logically partitioned computer system.
2. Background Art
Since the dawn of the computer age, computer systems have evolved into extremely sophisticated devices that may be found in many different settings. Computer systems typically include a combination of hardware (e.g., semiconductors, circuit boards, etc.) and software (e.g., computer programs). As advances in semiconductor processing and computer architecture push the performance of the computer hardware higher, more sophisticated computer software has evolved to take advantage of the higher performance of the hardware, resulting in computer systems today that are much more powerful than just a few years ago.
The combination of hardware and software on a particular computer system defines a computing environment. Different hardware platforms and different operating systems thus provide different computing environments. In recent years, engineers have recognized that it is possible to provide different computing environments on the same physical computer system by logically partitioning the computer system resources to different computing environments. The iSeries computer system developed by IBM is an example of a computer system that supports logical partitioning. If logical partitioning on an iSeries computer system is desired, partition manager code (referred to as a “hypervisor” in iSeries terminology) is installed that allows defining different computing environments on the same platform. Once the partition manager is installed, logical partitions may be created that define different computing environments. The partition manager manages the logical partitions to assure that they can share needed resources in the computer system while maintaining the separate computing environments defined by the logical partitions.
A computer system that includes multiple logical partitions typically shares resources between the logical partitions. For example, a computer system with a single CPU could have two logical partitions defined that allocate 50% of the CPU to each partition, that allocate 33% of the memory to the first partition and 67% of the memory to the second partition, and that allocate two different I/O slots to the two logical partitions, one per partition. Once logical partitions are defined and shared resources are allocated to the logical partitions, each logical partition acts as a separate computer system. Thus, in the example above that has a single computer system with two logical partitions, the two logical partitions will appear for all practical purposes to be two separate and distinct computer systems.
One problem with known logically partitioned computer systems occurs when the computer system initially powers up. The computer system may include multiple physical enclosures coupled together with cables or other interconnection mechanisms. A prior art method 200 is shown in
Prior art method 200 suffers from several drawbacks. First, the delay period in step 230 is typically selected to be long enough to allow all of the resources to be powered up and properly initialized. As a result, all logical partitions must wait until all resources for all logical partitions are ready before any logical partition may be started. The result is potentially long delays (on the order of minutes) in starting logical partitions after the computer system is powered on, because all logical partitions are delayed from starting for the worst case delay of all resources. A second drawback occurs when resources power on at non-deterministic delays, which could result from temporary disconnection or “offline for service” conditions. In this case, there may be one or more resources that are still unavailable even after the preset delay period expires. As a result, the logical partitions may be started in step 240 even though some have missing resources, possibly leading to those partitions being unable to boot (if the boot device is not powered or initialized at that time) or crashing when they discover the missing resources. Without a way to autonomically detect resources in a logically partitioned computer system, the computer industry will continue to suffer from the drawbacks in the prior art, discussed above.
A partition manager includes a resource detection mechanism that uses a persistent resource database to determine which resources were seen previously, and to determine which resources are required for a logical partition to start. Once all required resources for a logical partition are detected, the logical partition is started. In this manner, a logical partition may be started as soon as all of its resources are available, without waiting on the resources of other logical partitions. In addition, a missing required resource will prevent a logical partition from starting, thus avoiding the crash of a logical partition due to missing resources.
The preferred embodiments are well-suited to detecting I/O slots in a logically partitioned computer system. Note, however, that the preferred embodiments expressly extend to the detection of any hardware or software resource, including I/O buses, I/O communication channels, virtual I/O slots or devices, CPUs, and memory.
The foregoing and other features and advantages of the invention will be apparent from the following more particular description of preferred embodiments of the invention, as illustrated in the accompanying drawings.
The preferred embodiments of the present invention will hereinafter be described in conjunction with the appended drawings, where like designations denote like elements, and:
According to preferred embodiments of the present invention, a resource detection mechanism creates a persistent resource database on first boot and uses this database in subsequent boots to determine which resources were seen previously, and which are required for a selected logical partition to be started. Once all resources for a logical partition have been detected, the logical partition may be started without waiting for the resources of other logical partitions. The result is that logical partitions are initialized as soon as their required resources are detected (i.e., become available). The result is a boot sequence that starts logical partitions as soon as possible, and that avoid starting a logical partition if one or more of its required resources are not detected (i.e., are unavailable). The preferred embodiments also support powering off resources owned by a logical partition when the logical partition is powered off.
Note that the term “resource” as used in the specification and claims herein denotes any whole or fractional portion of hardware or software in the computer system that may be independently allocated to a logical partition. Examples of resources include: a physical 1/O slot; a group of I/O slots in a physical enclosure; a portion of a processor; a portion of memory; a virtual I/O slot; etc.
Referring to
Main memory 120 contains a partition manager 121, a resource detection mechanism 122, a resource database 124, and N logical partitions 125, shown in
Resource detection mechanism 122 detects when a resource becomes available. Resource database 124 is a persistent database that includes one or more tables that list resources detected during previous power on cycles of the computer system 100, and that indicates which resources are owned by each of the logical partitions. Resource detection mechanism 122 consults the resource database 124 to determine which resources are owned by a logical partition. Once the resource detection mechanism 122 detects all required resources owned by a logical partition, that logical partition may be started, without waiting for the resources for other logical partitions to be detected. Furthermore, the resource detection mechanism 122 waits until all resources for a logical partition are detected before starting the logical partition. Thus, if a resource is unavailable due to a hardware failure, service operation, cable disconnect, etc., the start of the logical partition will be delayed until the resource detection mechanism 122 has detected that all required resources are available. In this manner, resource detection mechanism 122 autonomically detects when all required resources are available and starts the corresponding logical partition as soon as possible, assuming the logical partition is scheduled to start at system power on.
It is also possible for a system administrator to schedule the start of logical partitions at a specified time. In this case, the detection of resources may occur before the scheduled time, but the start of the logical partition will be delayed until the scheduled time arrives. If one or more requires resources are still not available when the scheduled time arrives, the start of the logical partition will be further delayed until all required resources are detected. This autonomic detection of resources by resource detection mechanism 122 allows the partition manager 121 to automatically start a logical partition when resources become available. Thus, if a computer system is powered up without one if its I/O enclosures being powered for service of the I/O enclosure, the partition manager 121 will detect when the I/O enclosure is powered up and will automatically start all logical partitions that had all of their required resources detected except for those in the I/O enclosure.
The term “required resource” is broadly defined to mean any resource that is deemed necessary for a logical partition to start. The simplest implementation would assume that all resources in the resource database 124 that are owned by a selected logical partition are required for the selected logical partition to be started. However, it is also within the scope of the preferred embodiments to designate some resources as “required” while others may be designated “non-required” in the resource database. The determination of which resources are required and which are non-required could be made using any suitable heuristic by either a human operator or by a computer-implemented algorithm. By defining required and non-required resources, a logical partition may start once all of its required resources have been detected, even though one or more non-required resource has not yet been detected.
Operating system 126 is a multitasking operating system, such as OS/400, AIX, or Linux; however, those skilled in the art will appreciate that the spirit and scope of the present invention is not limited to any one operating system. Any suitable operating system can be used. Operating system 126 is a sophisticated program that contains low-level code to manage the resources of computer system 100. Some of these resources are processor 110, main memory 120, mass storage interface 130, display interface 140, network interface 150, system bus 160, and I/O slots 180. The operating system 126 in each partition may be the same as the operating system in other partitions, or may be a completely different operating system. Thus, one partition can run the OS/400 operating system, while a different partition can run another instance of OS/400, possibly a different release, or with different environment settings (e.g., time zone). The operating systems in the logical partitions could even be different than OS/400, provided it is compatible with the hardware (such as AIX or Linux). In this manner the logical partitions can provide completely different computing environments on the same physical computer system.
The partitions 125A-125N are shown in
Computer system 100 utilizes well known virtual addressing mechanisms that allow the programs of computer system 100 to behave as if they only have access to a large, single storage entity instead of access to multiple, smaller storage entities such as main memory 120 and DASD device 155. Therefore, while partition manager 121 and the partitions 125A-125N are shown to reside in main memory 120, those skilled in the art will recognize that these items are not necessarily all completely contained in main memory 120 at the same time. It should also be noted that the term “memory” is used herein to generically refer to the entire virtual memory of computer system 100.
Processor 110 may be constructed from one or more microprocessors and/or integrated circuits. Processor 110 executes program instructions stored in main memory 120. Main memory 120 stores programs and data that processor 110 may access. When computer system 100 starts up, processor 110 initially executes the program instructions that make up the partition manager 121, which performs the detection of resources and starts the logical partitions (once their resources are detected) by initializing the operating systems in the logical partitions.
Although computer system 100 is shown to contain only a single system bus, those skilled in the art will appreciate that the present invention may be practiced using a computer system that has multiple buses. In addition, the I/O interfaces that are used in the preferred embodiment each may include separate, fully programmed microprocessors that are used to off-load compute-intensive processing from processor 110, as in iSeries input/output processors, or may be simple industry standard I/O adapters (IOAs).
Display interface 140 is used to directly connect one or more displays 165 to computer system 100. These displays 165, which may be non-intelligent (i.e., dumb) terminals or fully programmable workstations, are used to allow system administrators and users to communicate with computer system 100. Note, however, that while display interface 140 is provided to support communication with one or more displays 165, computer system 100 does not necessarily require a display 165, because all needed interaction with users and other processes may occur via network interface 150.
Network interface 150 is used to connect other computer systems and/or workstations (e.g., 175 in
At this point, it is important to note that while the present invention has been and will continue to be described in the context of a fully functional computer system, those skilled in the art will appreciate that the present invention is capable of being distributed as a program product in a variety of forms, and that the present invention applies equally regardless of the particular type of computer readable signal bearing media used to actually carry out the distribution. Examples of suitable signal bearing media include: recordable type media such as floppy disks and CD RW (e.g., 195 of
While
A resource, once made available to the partition manager 121, is categorized as an available resource 460 if it has not yet been assigned to a logical partition, is categorized as a shared resource 470 if multiple logical partitions may access the resource, and is categorized as a dedicated resource 480 if it has been exclusively assigned to a logical partition.
Referring now to
If there are required resources for the selected logical partition that have not been detected (step 360=NO), method 300 determines whether any required resource is in a powered down state (step 380). If not (step 380=NO), method 300 loops back to step 340 and execution continues. If so (step 380=YES), power on for the powered down required resource(s) is initiated (step 382), and execution continues at step 340.
While the flow diagram of method 300 in
One specific implementation of resource database 124 is shown by the database table 500 in
Another aspect of partition manager 121 in the preferred embodiments is the ability to turn off resources owned by a logical partition when the logical partition is powered off. Referring to
The preferred embodiments provide a significant advance over the prior art by providing a persistent resource database that records which resources were seen in previous executions of a logically partitioned computer system. The resource database includes information that indicates which logical partition owns each resource. As a result, the resource database indicates all resources that are required for a logical partition to run. As soon as the last of the required resources is detected, the logical partition may be started without regard to the state of the other logical partitions. In this manner all logical partitions are started as soon as all of their required resources are available, without waiting for any resource owned by any other logical partition. In addition, no logical partition will start until all of its resources are available, which avoids the crash of a logical partition due to missing resources.
One skilled in the art will appreciate that many variations are possible within the scope of the present invention. Thus, while the invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that these and other changes in form and details may be made therein without departing from the spirit and scope of the invention. For example, while I/O slots are one specific type of resource that may be detected, any type of resource, both hardware and software, could also be detected within the scope of the preferred embodiments.
