Abstract: A “lazy commit” allows database transactions to be committed faster by not waiting for log records of the transaction to be written to disk. When a system crash occurs during the commit process, transactions may be lost because the log data is not available to recreate the transaction. While lazy commits speed up processing, they also increase the potential for data inconsistency. This invention introduces the concept of “durable reads”—transactions that require isolation from lazy commit transactions and which must be guaranteed to read only durably committed data. When durable read transaction attempts to read data changed by a lazy commit transaction, the system ensures the lazy commit transaction's changes are first made durable.

Abstract: The present invention relates generally to database and file system management and, more particularly, to automatic database and file system maintenance and repair to ensure data reliability. Various aspects of the present invention relate to responding and correcting data corruptions at a data page level for all data page types, as well as to recovery (including rebuild or restore operations) for various scenarios including, without limitation, index page corruptions (clustered and non-clustered), data page corruptions, and page corruptions in the log file.

Abstract: In order to provide recovery for a database stored on storage not meeting the WAL protocol requirements, for example, storage including a temporary cache and a second storage (e.g. an IDE disk with a temporary cache and a hard disk), a log is created including, for each changed page, a pre-image of the page before changes were effected. The log also includes one or more change log records logging changes made to the page. Periodic checkpoints occur in which the cached pages are flushed to the disk. Recovery proceeds with a redo pass through the active log and then with an undo pass, undoing any transactions that have not been committed.

Abstract: The subject invention relates to systems and/or methods that perform an authoritative and/or a non-authoritative restore of items in a data store. Backups are provided that include data associated with items and metadata related to the items that can include a history of operations and previous synchronizations to enable replications to converge after restoration. The operations that can be performed on the items include, for example, create, delete, update, move, etc. The items in the backups can be restored along with the metadata, which can be utilized to enable synchronization partners to converge based on a desired type of restoration.

Abstract: Systems and methods are disclosed herein that facilitate automatic database backup and restore for databases resident in personal computing devices, and which are transparent to a user, utilizing database page mirroring. Modifications to a data page in a data file can be validated and written to a backup, or mirror, database and then subsequently written to an original database after a predetermined time. An I/O latch on a mirrored data page can be limited to a duration of a single I/O write operation to facilitate sequential data page writing to each of the databases while mitigating potential for both databases to be written simultaneously, which can detrimentally affect data quality during a recovery operation.

Abstract: The subject invention relates to systems and methods that enable pausing and/or resuming a backup of file system items. The items are backed up in an order based on a unique property associated with each of the items. When the backup is paused, the unique property associated with a last backed up item prior to the pause is stored. Additionally, a timestamp associated with a snapshot from which the backup was taken can be stored with the unique property. Upon being resumed, the backup can continue from the paused location via utilizing the stored unique property. The backup can be resumed either employing an original snapshot associated with a time prior to the pause or a second snapshot related to a subsequent time. The subject invention can perform an initial backup of file system items and/or an incremental backup of such items. Additionally, the subject invention can support backing up a file system at disparate levels of granularity such as, for example, an item level.

Abstract: Systems and methods are disclosed that facilitate providing page-level database restore functionality upon detection of a corruption event. Updates to a data page in a database can trigger generation of a snapshot of the data page, and an update log can be maintained that stores information related to page updates. Subsequent snapshots can be generated at predetermined intervals and can trigger truncation of a log segment and initiation of a new log segment. Upon detection of page corruption, a most-recent uncorrupt snapshot of the corrupt page can be identified, copied to the location of the corrupt page in the database, and modified according to the log segment associated with the uncorrupt snapshot to make the page current as of the corrupting event, all of which can be performed to restore the database without having to take the database offline.

Abstract: An automatic database backup and restoration system comprises an interface component that receives statements relating to backing up at least a portion of a first database, the original database resident upon a consumer computing device. A backup component associated with the interface component automatically copies at least the portion of the first database and writes the copied portion to a backup database, the backup database is a full backup of the first database. The consumer computing device can be, for example, one of a laptop computer, a desktop computer, a personal digital assistant, and a cellular phone.

Abstract: A system and method for serialization and/or de-serialization of file system item(s) and associated entity(ies)is provided. A file system “item” comprises a core class which can include property(ies). An item can be simple or compound (e.g., includes other item(s) embedded in it). Associated with an item can be entity(ies) such as fragment(s), link(s) with other item(s) and/or extension(s). Through serialization, a consistent copy of the item and associated entity(ies), if any, can be captured (e.g., for transporting of the item and to reconstruct the item on a destination system). The serialization system includes an identification component that. identities entity(ies) associated with an item and a serialization component that serializes the item and associated entity(ies). The serialization component can further serialize a header that includes information associated with the item and associated entity(ies). The header can facilitate random access to the item and associated entity(ies) (e.g.

Abstract: The present invention relates generally to database and file system management and, more particularly, to automatic database and file system maintenance and repair to ensure data reliability. Various aspects of the present invention relate to responding and correcting data corruptions at a data page level for all data page types, as well as to recovery (including rebuild or restore operations) for various scenarios including, without limitation, index page corruptions (clustered and non-clustered), data page corruptions, and page corruptions in the log file.

Abstract: The present invention is directed a logical consistency checker (LCC) working alone or in conjunction with a physical consistency checker (PCC) and/or a data reliability system (DRS) for a database files system of a hardware/software interface system. Logical data correction pertains to logical data corruptions for entities (e.g., items, extensions, and/or relationships in an item-based operating system, where an item-based operating system is one example of an item-based hardware/software interface system). In this regard, a LCC analyses and corrects logical damage to entities representatively stored in the data store in order to ensure that all such entities in said data store are both consistent and conform to the data model rules.

Abstract: In order to provide a more efficient persistent storage device, one or more long-term storage media are included along with a non-volatile memory. In one embodiment, one portion of the non-volatile memory is used as a write buffer and a read cache for writes and reads to the long-term storage media. Interfaces are provided for controlling the use of the non-volatile memory as a write buffer and a read cache. Additionally, a portion of the non-volatile memory is used to provide a direct mapping for specified sectors of the long-term storage media. Descriptive data regarding the persistent storage device is stored in another portion of the non-volatile memory.