1. Field of the Invention
The present invention generally relates to continuous data protection and, more specifically, the present invention provides a system and method for utilizing local flash memory and a remote server for continuous data protection.
2. Related Art
Hard disks are fragile, have limited life-time, and their failure can make the stored precious data inaccessible. Most existing backup solutions create data copies periodically, leaving the recently created or modified data unprotected before the next backup time. Continuous Data Protection (CDP) systems attempt to solve this problem by creating remote copies of the data every time the data is saved to the disk (e.g., Tivoli® CDP). (Continuous data protection (CDP), also called continuous backup, refers to backup of computer data by automatically saving a copy of every change made to that data, essentially capturing every version of the data that the user saves. It allows the user or administrator to restore data to any point in time. CDP is a service that captures changes to data to a separate storage location. There are multiple methods for capturing the continuous changes involving different technologies that serve different needs. CDP-based solutions can provide fine granularities of restorable objects ranging from crash-consistent images to logical objects such as files, mail boxes, messages, and database files and logs.) IBM's Tivoli® Continuous Data Protection for Files is an integrated recovery solution that provides complete data protection in case of a corruption, user error, virus, or system failure. It installs and configures in minutes, and runs invisible in the background. For more information on IBM's Tivoli® Continuous Data Protection for Files, see http://www-306.ibm.com/software/tivoli/resource-center/storage/cdp.jsp?S_TACT=104CB62&ca=104CB627. Unfortunately, existing CDP systems create backup copies on the remote servers and do not protect the data when the network connection is unavailable, which is the common case for mobile users. Some CDP systems (e.g., SonicWALL® CDP—for more information on SonicWALL CDP, see http://www.sonicwall.com/us/backup_and_recovery.html) replicate the data on a redundant local hard drive. Unfortunately, this option is also not convenient for mobile users because the hard drives are bulky and consume extra power from the batteries.
Flash memory has become cheaper, bigger, and faster. (Flash memory is non-volatile computer memory that can be electrically erased and reprogrammed. It is a technology that is primarily used in memory cards, and USB flash drives (thumb drives, handy drive, memory stick, flash stick, jump drive) for general storage and transfer of data between computers and other digital products. It is a specific type of EEPROM that is erased and programmed in large blocks; in early flash the entire chip had to be erased at once. Flash memory costs far less than byte-programmable EEPROM and therefore has become the dominant technology wherever a significant amount of non-volatile, solid-state storage is needed. (For more information on flash memory, see http://electronics.howstuffworks.com/flash-memory.htm.)) As a result, it is now used for purposes other than removable drives. Hybrid drives contain flash memory to store recent writes before they are committed to the disk platters. (A hybrid drive, a.k.a. Hybrid Hard Drive (HHD), is a type of large-buffer computer hard disk drive. It is different from standard hard drives in that it employs a large buffer (up to 1 GB) of non-volatile flash memory to cache data during normal use. By primarily using this large buffer for non-volatile data storage, the platters of the hard drive are at rest almost all of the time, instead of constantly spinning as they are in current hard drives. This offers numerous benefits, chief among them speed, decreased power consumption, improved reliability, and a faster boot process. For more information on HHDs, see http://www.engadget.com/tag/hhd.) However, hybrid drives do not provide CDP because (1) the data is stored only in the flash memory before it is committed to the disk and (2) the data in the flash memory can be overwritten right after that. However, flash memory provides several benefits: (1) hybrid drives can save power because they can save some written data in the flash memory and thus postpone hard disks' spin-up operations if their platters are not spinning; and (2) flash memory has constant and small data access times. Therefore, hybrid disks and Windows® Vista's ReadyBoost use flash memory to serve random read requests to improve performance. (ReadyBoost is a disk caching technology first included with Microsoft's Windows Vista operating system. It aims to make computers running Windows Vista more responsive by using flash memory on a USB 2.0 drive, SD card, CompactFlash, or other form of flash memory, in order to boost system performance).
Therefore, there exists a need for a solution that solves at least one of the deficiencies of the related art.