Hitachi Review Vol. 61 (2012), No. 2 65 Logical Partitioning Feature of CB Series Xeon Servers Suitable for Robust and Reliable Cloud Hitoshi Ueno, Ph. D., PE.jp OVERVIEW: LPAR is Hitachi’s own server virtualization feature for Shinichi Matsumura Hitachi Compute Blade servers. LPAR stands for logical partitioning used by mission-critical systems such as mainframes and offers excellent performance, including reliability, stability, and maintaining virtual server separation. The implementation of logical partitioning on Xeon*1 servers significantly expands the scope for applying virtualization in private clouds because it means that virtualization of mission-critical systems can be used even on Xeon servers. Hitachi is currently developing new solutions that improve ease-of-operation and simplify installation, and the number of sites using LPAR for cloud is increasing. LPAR is already a proven virtualization feature and Hitachi intends to continue with development to make further improvements in performance and reliability. INTRODUCTION is that, compared to the VM (virtual machine) method, HITACHI aims to create new value through its next it is easier to configure systems with higher reliability generation of IT (information technology) platforms and performance. However, very few virtualization and virtualization is a key technology for implementing products support the use of logical partitioning on the infrastructure clouds that will support this Xeon processors and other Xeon servers (see Table 1). endeavor. Within this, Hitachi Compute Blade (CB) Virtualization based on logical partitioning has logical partitioning feature (LPAR) provides a server been widely used for mission-critical applications virtualization feature critical to data processing. in the past and, unlike virtualization software from This article describes the characteristics of the other vendors, Hitachi’s LPAR feature also extends LPAR, a server virtualization feature that enhances this capability to Xeon servers. Advanced hardware the virtualization environment for CB servers, along support is required to implement logical partitioning with examples of its use. and therefore it is very helpful that Hitachi is also a server vendor. LPAR can be used on the CB2000 and HITACHI COMPUTE BLADE LPAR FEATURES CB320 servers in the CB series. Support for Logical Partitioning on Xeon Servers LPAR is a server virtualization feature used for Resource Sharing for Cloud logical partitioning on mainframes and commercial Under logical partitioning control, abstraction of UNIX*2 servers. An advantage of logical partitioning hardware resources such as CPUs (central processing TABLE 1. Characteristics of Server Virtualization Features (Software) from Different Vendors Logical partitioning is already used for mission-critical applications on mainframes, commercial UNIX servers, and other similar computer systems. Hitachi Compute Blade LPAR is a distinctive virtualization method that allows logical partitioning to be used for mission-critical applications on Xeon servers. Category Xeon servers Commercial UNIX servers Mainframe Vendor Hitachi (LPAR) Vendor A Vendor B Vendor C Vendor D Hitachi Guest OS Windows*1, Linux*2 Windows, Linux Windows, Linux Vendor C UNIX, Linux Vendor D UNIX VOS3 Type LPAR VM VM LPAR LPAR LPAR Vendor type Server vendor Software vendor Software vendor Server vendor Server vendor Server vendor OS: operating system LPAR: logical partitioning VOS3: Virtual-storage Operating System 3 VM: virtual machine *1 Windows is a registered trademark of Microsoft Corporation in the United States and other countries. *2 Linux is the registered trademark of Linus Torvalds in the U.S. and other countries. *1 Xeon is a trademark of Intel Corporation in the U.S. and/or other *2 UNIX is a registered trademark of The Open Group. countries. Logical Partitioning Feature of CB Series Xeon Servers Suitable for Robust and Reliable Cloud 66 I/O pass-through model Hypervisor emulation model Server blade Processor group Physical CPU cores LPAR 1 LPAR 2 LPAR n VM 1 VM 2 VM n CPU CPU CPU CPU CPU CPU CPU CPU OS OS OS OS OS OS core core core core core core core core Standard Standard Standard Driver Driver Driver Logical driver driver driver (SCSI) (SCSI) (SCSI) CPU cores Hitachi Virtualization Manager Virtualization Logical Logical Logical Logical Virtualization assistant software Emulator core core core core LPAR 1 LPAR 2 LPAR 3 LPAR 4 LPAR 5 LPAR 6 I/O card I/O card I/O card I/O card (Shared (Shared (Shared (Shared (Exclusive (Exclusive use of use of use of use of use of CPU) use of CPU) CPU) CPU) CPU) CPU) Hardware User C User C support for FC-SW FC-SW User A User A User B User B sharing also available Storage Storage CPU: central processing unit LU for LU for LU for LU for virtual LPAR 1 LPAR 2 LPAR nn file system Fig. 2—Processor Group Feature for Preventing Users from I/O: input/output FC-SW: Fibre Channel switch LU: logical unit Impacting Each Other. SCSI: Small Computer System Interface In addition to using exclusive mode to keep users discrete (user Fig. 1—I/O Architecture for Logical Partitioning and VM C), the LPAR feature can also configure the use of processor Methods. groups for flexible sharing within a user’s own department Because logical partitioning uses a pass-through model, which while maintaining discreteness from other departments (users A allows the guest OS to access I/O cards directly, the OS can and B share two cores, which are split between them). make full use of hardware functions. VM, on the other hand, has excellent configuration flexibility because it uses an emulator to deal with hardware differences. feature that allows systems to be configured in such a way that different departments cannot affect one another (see Fig. 2). units), memory, and I/O (input/output) is kept to a minimum so that the guest OS (operating system) Use of Cloud for Heavily Loaded Systems can have full control of hardware operation. This To allow for the case in which a mission-critical gives access to the advanced functions of external system with a heavy workload is migrated from hardware. a commercial UNIX machine to a Xeon server, a In terms of their I/O control architectures, logical dedicated I/O structure was provided in which high- partitioning uses an I/O pass-through model, whereas throughput I/O processing is entirely separated into VM uses a hypervisor emulation model (see Fig. 1). different logical partitions. Doing so allows even The former is suitable for cloud applications mission-critical systems that handle heavily loaded because it not only allows the guest OS to have to be migrated to the cloud. access to hardware functions such as Hitachi’s Many past projects involving Xeon server ShadowImage function for copying supplementary integration dealt with systems with comparatively light volumes on storage devices, it also assumes a multi- workloads, which meant sharing I/O cards caused few tenant environment, making the logical partitions more performance bottlenecks. However, as some mission- independent and reducing interference between them. critical systems have a heavy I/O load, a dedicated I/O function that allows I/O cards to use particular logical LPAR FUNCTIONS FOR RELIABLE partitions exclusively was provided. OPERATION Preventing Impact on Systems Belonging to Non-stop Operation through Hardware Failures Other Companies or Departments An issue when using server virtualization is that, Because cloud-based systems share particular if a server hardware failure occurs, all of the virtual hardware resources between different companies or servers on that machine halt and the resulting service departments, there is a risk that one of the virtual disruption has a major impact. servers may use a large proportion of a hardware Because the LPAR feature is implemented in the resource due, for example, to an application program firmware level, it has superb hardware control and bug or unanticipated surge in system workload, and can be used to implement cloud platforms with a that this will impact the other virtual servers. high level of fault tolerance. On the high-performance LPAR is equipped with a dedicated CPU feature, CB2000 server blades, in particular, the operation provides flexible resource allocation within a user’s can be controlled such that, when a hardware failure own department, and supports a processor group occurs that only impacts specific logical partitions, Hitachi Review Vol. 61 (2012), No. 2 67 Server blade Functions for manipulating and configuring logical partitions CPU CPU CPU CPU CPU CPU CPU CPU core core core core core core core core L3 cache memory Failure LPAR Hitachi Isolate fault. OS OS OS OS Reboot logical Virtualization Manager partition. Logical Logical Logical Logical Logical Logical Logical Logical LPAR core core core core core core core core OS OS OS OS OS OS Reboot OS OS Hitachi Virtualization Manager Navigator LPAR LPAR LPAR LPAR Memory Indicates that part of memory is mapped for use as L3 cache memory. Performance monitor OS Guest OS Fig. 3—High Level of Fault Tolerance Allowing Operation to Fig. 4—Administration of Virtualization Environment Using Continue as much as Possible after Hardware Failure. Hitachi Virtualization Manager Navigator. When a cache memory failure occurs, only the logical partitions The LPAR feature is used to administer the virtualization that were using that cache memory are halted. The other logical environment. It includes a performance monitor and functions partitions continue to run. The halted logical partitions are for manipulating and configuring logical partitions. rebooted, fallback of the failed cache memory is performed, and operation resumes. Manager Navigator is installed in and run from an administration PC (personal computer) and includes fallback of only those logical partitions are performed a performance monitor and configuration viewer, as so that other logical partitions can continue to run well as logical partition migration and logical partition (see Fig. 3). LPAR also includes a fault early warning operation and setup functions (see Fig.