Patent Publication Number: US-2009240881-A1

Title: System and Method for Information Handling System Operation With Different Types of Permanent Storage Devices

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates in general to the field of information handling system storage devices, and more particularly to a system and method for an information handling system operation with different types of permanent storage devices. 
     2. Description of the Related Art 
     As the value and use of information continues to increase, individuals and businesses seek additional ways to process and store information. One option available to users is information handling systems. An information handling system generally processes, compiles, stores, and/or communicates information or data for business, personal, or other purposes thereby allowing users to take advantage of the value of the information. Because technology and information handling needs and requirements vary between different users or applications, information handling systems may also vary regarding what information is handled, how the information is handled, how much information is processed, stored, or communicated, and how quickly and efficiently the information may be processed, stored, or communicated. The variations in information handling systems allow for information handling systems to be general or configured for a specific user or specific use such as financial transaction processing, airline reservations, enterprise data storage, or global communications. In addition, information handling systems may include a variety of hardware and software components that may be configured to process, store, and communicate information and may include one or more computer systems, data storage systems, and networking systems. 
     Information handling systems typically store information locally and remotely. Local storage generally includes permanent and non-permanent storage. For example, non-permanent storage includes random access memory (RAM) which requires power to maintain information. Permanent storage typically includes a hard disk drive (HDD) and firmware. A hard disk drive stores information on a rotating magnetic media that stores and maintains information by altering magnetic qualities of a disk. Firmware stores information in flash memory that maintains information even when power is removed. In a typical information handling system, firmware stored in flash memory includes instructions to initiate a boot of the system so that a processor can retrieve an operating system from the hard disk drive and run the operating system using the RAM to coordinate operation of the various components and applications running on the information handling system. Remote storage is typically permanent storage that is accessible to information handling systems through an external cable or a network. For example, hard disk drives are organized in JBOD or RAID configurations and accessed through a storage area network (SAN). Remote storage of information typically provides better access at an enterprise level and better security in that redundant storage is less complex from a central location. 
     Advances in flash memory have led to the introduction of another type of permanent storage for information handling systems, the solid state drive (SSD). SSDs are essentially HDDs that use flash memory for permanent storage instead of a magnetic disk. SSDs typically use less power than HDDs because SSDs do not rely on moving parts, such as a rotating magnetic disk. SSDs also tend to be more robust than HDDs, which are sometimes damaged by movement of the information handling system. The reduced power consumption and increased robustness of SSDs make SSDs especially attractive for portable information handling systems that rely on internal batteries and that are often subjected to external shocks. However, SSDs tend to cost more than HDDs and tend to have smaller storage capacities. HDDs also tend to outperform SSDs when writing and reading sequential data, such as video information, while SSDs outperform HDDs in retrieving randomly stored information. The differences in performance relate to differences in the operation of HDDs and SSDs. For example, HDDs locate information by placement of an arm over a rotating disk while SSDs have to erase information in storage before performing writes. 
     SUMMARY OF THE INVENTION 
     Therefore, a need has arisen for a system and method that manages information handling system operations using different types of permanent storage devices. 
     In accordance with the present invention, a system and method are provided which substantially reduce the disadvantages and problems associated with previous methods and systems for managing different types of storage devices associated with an information handling system. A storage arbitrator arbitrates storage tasks associated with an information handling system between a hard disk drive and a solid state drive based on predetermined factors to achieve desired performance improvements, such as improved storage and retrieval speeds or reduced power consumption. 
     More specifically, an information handling system has plural processing components that cooperate to use information. A hard disk drive and a solid state drive cooperate to store and retrieve information. A storage controller, such as a RAID controller, manages the use of the storage devices, such as by keeping a mirror copy on each storage device. A storage arbitrator associated with the storage controller arbitrates storage tasks between the solid state drive and hard disk drive based on predetermined factors. For example, the storage arbitrator arbitrates storage tasks based on the type of information associated with the storage tasks. Writes and reads of sequential information, such as video, are performed with the hard disk drive while writes and reads of random non-sequential information are performed with the solid state drive. As another example, with reduced available power, such as when the information handling system runs on battery power, the storage arbitrator powers down the hard disk drive to save power and uses the solid state drive for storage tasks. The hard disk drive periodically powers up to mirror information stored on the solid state drive. 
     The present invention provides a number of important technical advantages. One example of an important technical advantage is that storage tasks are arbitrated between different types of storage devices to provide desired information handling system improvements. For example, write and read operations are performed more efficiently by analyzing the data involved to determine whether the data is sequential or non-sequential so that sequential information uses the hard disk drive and non-sequential information uses the solid state drive. As another example, with reduced available power, such as during battery operations, the solid state drive is used for storage tasks while the hard disk drive is powered down to reduce power consumption. The hard disk drive is periodically powered up to copy the writes performed on the solid state drive. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention may be better understood, and its numerous objects, features, and advantages made apparent to those skilled in the art by referencing the accompanying drawings. The use of the same reference number throughout the several figures designates a like or similar element. 
         FIG. 1  depicts a block diagram of a portable information handling system that arbitrates storage tasks between a solid state drive and a hard disk drive; 
         FIG. 2  depicts a block diagram of a storage controller that arbitrates storage tasks between one or more solid state drives and one or more hard disk drives; and 
         FIG. 3  depicts a flow diagram of a process for arbitrating storage tasks between a solid state drive and a hard disk drive. 
     
    
    
     DETAILED DESCRIPTION 
     Arbitrating storage tasks of an information handling system between a hard disk drive and a solid state drive provides improved speed for storage operations, improved security for stored information and reduced power consumption for the information handling system. For purposes of this disclosure, an information handling system may include any instrumentality or aggregate of instrumentalities operable to compute, classify, process, transmit, receive, retrieve, originate, switch, store, display, manifest, detect, record, reproduce, handle, or utilize any form of information, intelligence, or data for business, scientific, control, or other purposes. For example, an information handling system may be a personal computer, a network storage device, or any other suitable device and may vary in size, shape, performance, functionality, and price. The information handling system may include random access memory (RAM), one or more processing resources such as a central processing unit (CPU) or hardware or software control logic, ROM, and/or other types of nonvolatile memory. Additional components of the information handling system may include one or more disk drives, one or more network ports for communicating with external devices as well as various input and output (I/O) devices, such as a keyboard, a mouse, and a video display. The information handling system may also include one or more buses operable to transmit communications between the various hardware components. 
     Referring now to  FIG. 1 , a block diagram depicts a portable information handling system  10  that arbitrates storage tasks between a solid state drive  12  and a hard disk drive  14 . Solid state drive  12  performs storages tasks in much the same way as hard disk drive  14  except that solid state drive  12  has flash memory while hard disk drive  14  has a rotating magnetic disk. Portable information handling system  10  is built in a portable chassis  16  having a rotationally coupled lid  18 . Processing components within chassis  16  cooperate to process information. For example, a CPU  20  runs an operating system and applications retrieved from solid state  12  and hard disk drive  14  with cooperation of RAM  22  and a chipset  24 , which coordinates operation of the processing components at a physical layer. Rotationally coupled lid  18  has an integrated display  26  which presents information as visual images. Chipset  24  and an operating system running on CPU  20  cooperate to manage power consumption, such as by selectively enabling or disabling components based on whether information handling system  10  runs on internal battery power or external power provided from an AC adapter. 
     Chipset  24  includes a RAID controller  28  which provides information security by creating a mirror copy of stored information on both solid state drive  12  and hard disk drive  14 . If, for example, solid state drive  12  has less capacity than hard disk drive  14 , RAID controller  28  can mirror solid state drive  12  to a partition of hard disk drive  14 , thus leaving addition partitions of hard disk drive  14  for other tasks, such as mirroring other solid state drives  12  should information handling system  10  have plural solid state drives. A storage arbitrator  30  associated with RAID controller  28  arbitrates storage tasks, such as reads, writes and mirroring operations, between solid state drive  12  and hard disk drive  14  based on one or more predetermined factors. For example, storage arbitrator  30  arbitrates storage tasks based on an analysis of the type of information involved in the storage task, the available power to perform the storage task and information security constraints. Where analysis of information involved in a read or write indicates an efficiency associated with a storage device, storage arbitrator  30  performs the storage task with the more efficient device. For instance, sequential information is read or written with hard disk drive  14  while non-sequential or random information is read or written with solid state drive  12 . In alternative embodiments, a solid state drive might handle sequential information more efficiently while a hard disk drive might handle non-sequential information more efficiently; the present disclosure assigns storage duties based on the characteristics of the storage devices for a given system. As another example, the solid state drive is used for frequently accessed information, such as the operating system and applications, while the hard disk drive is used for less-frequently accessed information, such as inactive documents or backed up information. Where power is limited, such as during battery powered operations, storage arbitrator  30  performs storage tasks so as to reduce power consumption. For example, hard disk drive  14  is powered down to take advantage of reduced power consumption by solid state drive  12 . Periodic powering up of hard disk drive  14  allows mirroring of information as desired for improved information security. 
     Referring now to  FIG. 2 , a block diagram depicts a storage controller  28  that arbitrates storage tasks between one or more solid state drives  12  and one or more hard disk drives  14 . For example, storage controller  28  has a network interface to support communications over a network  34 , such as a storage area network (SAN). Solid state drives  12  and hard disk drives  14  communicated through storage device interfaces  36  to accept storage tasks as assigned by storage arbitrator  30 . A detector  32  determines the type of storage device coupled to each interface  36  so that arbitrator  30  assigns storage tasks to each type of storage device based on predetermined factors. For example, frequently accessed information is stored in solid state drives  12  which remain powered on while less-frequently accessed information is stored in hard disk drives  14 , which may be powered down to reduce power consumption. 
     Referring now to  FIG. 3 , a flow diagram depicts a process for arbitrating storage tasks between a solid state drive and a hard disk drive. Storage devices transition between a performance mode  38 , a balanced mode  40  and a power savings mode  42 . The process starts at step  44  with initiation of a solid state drive and a hard disk drive in a RAID configuration. At step  46 , power is limited, such as by removal of external power from a portable information handling system. At step  48 , a determination is made of the type of operating mode that is selected. If a performance mode is selected to provide maximized information security, the process continues to step  49  to have both storage devices remain powered up and in the RAID configuration. If at step  48  a power savings mode is determined, the process continues to step  50  to power down the hard disk drive so that only the solid state drive runs. At step  52 , a log is made of changes to the solid state drive image. At step  54 , a determination is made of whether external power has returned. If not, the process returns to step  52  to continue logging changes made to the solid state drive. If at step  54  external power returns, the process continues to step  56  to power up the hard disk drive and to step  58  to mirror new data from the solid state drive to the hard disk drive based on the log. 
     If at step  48 , a balance mode of operation is selected, the process continues to step  60  to power down the hard disk drive and run only the solid state drive. At step  62 , changes made to the solid state are logged. At step  64 , a determination is made of whether a data threshold is exceeded, such as greater than a predetermined number of writes to the solid state drive. If no, the process continues to step  66  to determine if external power is returned. If external power is not returned, the process continues to step  62  to continue to log changes made to the solid state drive. If external power is returned, the process continues to step  56 . If at step  64  the data threshold is exceeded, the process continues to step  68  to power up the hard disk drive. At step  70 , the new data written to the solid state drive is mirrored to the hard disk drive with the log. At step  72 , a determination is made of whether external power is returned. If external power is not returned, the process continues to step  60  to keep the HDD powered down and run with only the SSD. If external power is returned, the process continues to step  44 . 
     Although the present invention has been described in detail, it should be understood that various changes, substitutions, and alterations can be made hereto without departing from the spirit and scope of the invention as defined by the appended claims.