Abstract: A set of six atomic primitives are provided for a database management system that may be used in combination to provide all of the common features and functions of a clustered database, including data failover, auto-healing, and elastic scaling. These six atomic primitives include CREATE, DROP, DETACH, ATTACH, COPY, and PROMOTE. Of particular note, it is shown that by maintaining appropriate metadata, including the status of each instance of each partition in the cluster, the versatility and reliability of this set of primitives is sufficient to implement each of the aforementioned data failover, auto-healing, and elastic scaling functions with high efficiency using a minimal number of these primitives. Each primitive is atomic (such that the cluster clearly in one state or another) and online (a workload of reads and writes is uninterrupted while the primitive runs), and each primitive is scoped to a single partition of data, thereby enabling parallel processing.

Abstract: Methods, apparatus and articles of manufacture are disclosed to manage inter-virtual disk relations in a modularized virtualization topology using virtual hard disks. An example method includes, in response to a request to access a first virtual hard disk in a virtual computing environment, determining, with a machine, whether an inter-virtual hard disk rule associated with a second virtual hard disk is invoked and whether a condition of the inter-virtual hard disk rule is satisfied. The example method also includes identifying, with the machine, a response action if the inter-virtual hard disk rule is invoked and the condition is satisfied, and executing the response action with the machine.

Abstract: A failover system can receive active data from user devices running an application specific to a service entity providing an application service. For each user device, the active data can indicate a current status. The failover system can transmit restoration data to the user devices for storage to restore the current status of the user devices in the case of a failover event. When a failover event occurs, the failover system can recover the restoration data from a first user device to restore the current status of the application service for the first user device.

Abstract: In one aspect, a method includes storing a virtual machine disk in a first logical unit stored on a data store; replicating the first virtual machine disk used by a first virtual machine at a second virtual machine disk stored on a second logical unit on a cloud array storage device; storing changes to the first virtual machine disk on a journal stored on the data store; periodically rolling each virtual machine disk of virtual machines on the second logical unit to a same-point-in-time using the journal and taking a snapshot of the second logical unit at the same point-in-time and sending the snapshots to a cloud storage network.

Abstract: Methods and a system are provided. A method includes maintaining an in-page log for records in each of a plurality of data pages of a multi-version database. The method further includes adding record update information to the in-page log when a corresponding one of the records is deleted or updated. The method also includes consulting the in-page log for a recently updated one of the records or a recently deleted one of the records to determine a record status thereof. The method additionally includes spilling, by a processor-based overflow manager, to overflow pages when the in-page log is full. The data pages include any of row-oriented data pages and column-oriented data pages.

Abstract: The present invention discloses a method and apparatus. The method comprises: a method for backing up an application, the application running across multiple virtual machines, the method comprising: in response to a need of backing up the application, executing a first set of scripts that are used for, prior to the backup, coordinating the multiple virtual machines to enter into a preparation state; in response to the first set of scripts being executed completely, triggering a backup operation of at least one backup agent that manages the multiple virtual machines, the backup operation comprising the backup agent locating data related to the application on the respective virtual machines managed thereby; in response to completion of the backup operation, executing a second set of scripts that are used for restoring running of the multiple virtual machines.

Abstract: A cluster file system comprises a parallel file system and a plurality of burst buffers, with the burst buffers collectively configured to provide an interface between the parallel file system and compute nodes of a computer system. Each of the burst buffers comprises a virtual file system component and a metadata server component. The virtual file system components of respective ones of the burst buffers collectively implement a virtual file system. Metadata relating portions of the virtual file system to portions of the parallel file system is stored in a distributed manner over the metadata server components of the respective burst buffers. Each burst buffer independently manages its own flash memory, but the burst buffers are configured such that data consistency is ensured across their flash memories. The virtual file system illustratively comprises a parallel log-structured file system (PLFS) and the metadata server components illustratively comprise respective TO forwarding servers.

Abstract: Methods and a system are provided. A method includes maintaining an in-page log for records in each of a plurality of data pages of a multi-version database. The method further includes adding record update information to the in-page log when a corresponding one of the records is deleted or updated. The method also includes consulting the in-page log for a recently updated one of the records or a recently deleted one of the records to determine a record status thereof. The method additionally includes spilling, by a processor-based overflow manager, to overflow pages when the in-page log is full. The data pages include any of row-oriented data pages and column-oriented data pages.

Abstract: Described are methods, systems and computer readable media for data source refreshing using an update propagation graph with feedback cyclicality.

Abstract: A method for managing resources of virtual backup appliances is described. The method includes receiving, by a backup management server (BMS), a request to back up a plurality of virtual machines (VMs), determining, at the BMS, a set of VMs to be backed up from the plurality of VMs that yields a maximum performance for the backup request without causing the set of VM servers to become bottlenecked, wherein the determination is performed based on at least one of a concurrency limit of the virtual backup appliance (VBA) and any VBA proxies corresponding to the set of VMs, and a set of one or more data performance metrics of one or more storage devices in the set of VM storage arrays, and sending one or more backup jobs to the VBA to back up the determined set of VMs to be backed up to a backup storage system.

Abstract: In accordance with an embodiment, described herein is a system and method for providing administrative command progress status for use with a cloud computing environment. In accordance with an embodiment, a job manager service provides an application program interface which receives administrative commands to be processed within the cloud environment as jobs, wherein each instance of the administrative commands is associated with a unique job identifier. A command line interface allows a user to issue a command to be processed within the cloud environment as a job. During progress of a job associated with an annotated command, a status associated with the progress of the job is determined and provided to the command line interface. For example, the system can provide job progress status during these operations, to reassure the user that the operation is proceeding normally.

Abstract: A unifying memory controller (UMC) to send and receive data to and from a local host. The UMC also may manage data placement and retrieval by using an address mapper. The UMC may also selectively provide power to a plurality of memory locations. The UMC may also manage data placement based on a policy that can make use of a property stored in the metadata storage location. The property may be a property describing the data that is being managed. The UMC also may use its own local cache that may store copies of data managed by the circuit.

Abstract: A technique for providing access to a data object serving as a target of snapshot-shipping replication includes taking a system snap of the data object after completion of each of multiple snapshot-shipping updates. In response to a data storage system receiving an IO (input/output) request to read and/or write to the data object, a data storage system redirects the IO request to a previously generated system snap, so that the data storage system performs the operation specified in the IO request on the system snap rather than of the data object itself.

Abstract: Systems and techniques for a distributed file system element collection are described herein. A node may identify a state of a file system element, which is identified in a file system element definition, from a local data store. The state corresponds to a distribution action. The file system element definition is one of a plurality of file system element definitions in a collection schema of a collection to which the node is a member. The node may, in response to identifying the state of the file system element, issue a communication to some members of the collection in furtherance of completion of the distribution action. A response may be received by the node from a participant node in the list of participant nodes. The node may complete the distribution action using content from the response.

Abstract: In an embodiment of the present invention, a method can include converting a data-full snapshot having a plurality of user data and corresponding metadata to a dataless snapshot. The dataless snapshot stores the metadata corresponding to the user data. Converting the data-full snapshot to the dataless snapshot includes removing the user data from the data-full snapshot. The metadata can be at least one of a checksum or hash of the corresponding user data.

Abstract: A computer-implemented method and system for analyzing and maintaining data security in backup data, comprising of: accessing backup data of file systems on-site or remotely from a backup server; determining which data is present in a backup system; defining an abnormality data selection criteria to identify security components within the scope of said backup system; performing a data security analysis on backup data; if data abnormality in data are detected in backup data, determining compromised target files, identifying all other files created or modified associated with said compromised target files, including files having a parent-child relationship in both up and down directions of the parent-child tree, including files that are other children of the compromised files in the parent-child tree, including files created or modified by of the compromised files, and including data launched from those files.

Abstract: Various of the disclosed embodiments provide for recovery following inadvertent errors in a Log-Structured File System (LSFS). Particularly, embodiments mitigate inadvertent errors introduced by a file system consistency check operation by creating file system images at an appropriate time. The images may be stored within the portion of the file system accessible to a user. The images may be created in conjunction with the mounting of the file system and in such a fashion as to preserve the file system data should an error occur. Restoring the system to one of the images may remove any errors introduced by the consistency check, or similar, operation.

Abstract: A data analysis system and method for determining a measure of overlap between data entries in a number N of columns in a database. Sorted hash lists are provided. An N×N matrix having cells Cij is provided. A set of N indexed read pointers pointing to the hash lists are provided. Each read pointer points to the first entry of the associated hash list. The value of cells Cij in the matrix having indices i,j, wherein i and j each correspond to any of the index numbers of the read pointers pointing to the lowest value are incremented. The read pointer(s) pointing to the lowest value are incremented to point to the next different hash value(s). This is repeated until the last read pointer(s) points to the last entry of the associated hash list.

Abstract: The disclosed embodiments disclose techniques for executing a cloud command for a distributed filesystem. Two or more cloud controllers collectively manage distributed filesystem data that is stored in one or more cloud storage systems; the cloud controllers ensure data consistency for the stored data, and each cloud controller caches portions of the distributed filesystem. During operation, a cloud controller presents a distributed-filesystem-specific capability to a client system as a file in the distributed filesystem (e.g., using a file abstraction). Upon receiving a request from the client system to access and/or operate upon this file, the client controller executes an associated cloud command. More specifically, the cloud controller initiates a specially-defined operation that accesses additional functionality for the distributed filesystem that exceeds the scope of individual reads and writes to a typical data file.

Abstract: An administrator provisions a virtual disk in a remote storage platform and defines policies for that virtual disk. A virtual machine writes to and reads from the storage platform using any storage protocol. Virtual disk data within a failed storage pool is migrated to different storage pools while still respecting the policies of each virtual disk. Snapshot and revert commands are given for a virtual disk at a particular point in time and overhead is minimal. A virtual disk is cloned utilizing snapshot information and no data need be copied. Any number of Zookeeper clusters are executing in a coordinated fashion within the storage platform, thus increasing overall throughput. A timestamp is generated that guarantees a monotonically increasing counter, even upon a crash of a virtual machine. Any virtual disk has a “hybrid cloud aware” policy in which one replica of the virtual disk is stored in a public cloud.

Abstract: A system includes reception, at a target database system, of a request to recover a backup created by a source database system into the target database system, where the request comprises a system identifier of the source database system, determination of a backup tool configuration file associated with the source database system based on the system identifier of the source database system, request of a recovery of the backup into the target database system using the backup tool configuration file, copying of a backup catalog of the source database system into a storage location associated with the target database system, and appending of a system change marker to the copied backup catalog, wherein the system change marker comprises the system identifier of the source database system.

Abstract: A management system and method for remediating poor-performing clients running in a distributed computer system uses a machine learning technique to automatically detect one or more poor-performing clients among a plurality of clients running in the distributed computer based on at least performance data and resource usage data of the clients. An action is then initiated to mitigate the effects of the poor-performing clients.

Abstract: A network element of an Internet Protocol multimedia subsystem buffers network resource usage information in the cloud. After generating network resource usage information based on an observation of network resource usage, the network element transmits the network resource usage information to a cloud-based storage service for buffering. Once a network resource usage collection function is available, the network element retrieves the network resource usage information from the cloud-based storage service and transmits it to a charging collection function for generation of call detail records.

Abstract: A set of variables referred to by unified extensible firmware interface (UEFI) firmware is restored. The UEFI firmware stored in a read-only memory (ROM) is firstly executed after power-up. The UEFI firmware writes a variable set related to boot, into a variable area. As an operating system (OS) also writes a set of variables into the variable area, the boot-related variable set may be altered. The variable set is saved into a prescribed area, such as a universal serial bus (USB) memory key, when the computer boots normally. If alteration of the variable set in the reference area is detected during a boot of the computer, the variable set in the reference area is replaced with the saved variable set. The variable set alteration may be detected using a detection flag which is set immediately after a boot is started and reset immediately before an OS is loaded.

Abstract: This disclosure relates to a method, article of manufacture, and apparatus for generating a snapshot history map. In some embodiments, this includes retrieving at least one storage pairing, extracting a snapshot history based on the at least one storage pairing, the snapshot history including a list of snapshot details sorted in chronological order, and displaying a chronological representation of the snapshot history based upon the snapshot details sorted in chronological order. In some embodiments, this further includes generating the snapshot details after performing successful snapshots using the at least one storage pairing, and extracting the snapshot history based on the at least one storage pairing includes extracting the snapshot history of the at least one pairing by querying a database.

Abstract: A container database stores redo records and logical timestamps for multiple pluggable databases. When it is detected that a first read-write instance of the pluggable database is opened and no other read-write instances of the pluggable database are open, offline range data associated with the pluggable database is updated. When it is detected that a second read-write instance of the pluggable database is closed, and the second read-write instance is the last open read-write instance, the offline range data associated with the pluggable database is updated. The pluggable database is restored to a logical timestamp associated with a restore request based on the offline range data.

Abstract: Computerized methods and systems for automating a process of creating and mounting live copies of data to applications in accordance with workflows that specify procedures for creating and mounting the live copies of data to the applications. The methods and systems comprise executing at least one workflow associated with a data object based on a triggering event, and executing a set of configurable work actions associated with the at least one workflow; creating a snapshot of data volumes associated with the data object; creating liveclone volumes based on the snapshot of the data volumes, and mounting and dismounting the liveclone volumes to and from at least one application.

Abstract: An apparatus acquires a packet transmitted according to a protocol employing block access, from a communication network, and determines which one of a system attribution block storing stores file system attribution data, a file attribution block storing file attribution data, and a file name block storing file name data the packet is related to. The apparatus calculates a block number of the file attribution block, based on addresses provided to the system and file attribution blocks, when the packet is determined to be related to the file attribution block. The apparatus calculates an identification number of each piece of the file attribution data, based on the system attribution data and the calculated block number, and associates file attribution data stored in the file attribution block with file name data stored in the file name block, based on the calculated identification numbers and identification numbers provided to the file name data.

Abstract: A method for managing resources of virtual backup appliances is described. The method includes receiving, by a backup management server (BMS), a request to back up a plurality of virtual machines (VMs), determining, at the BMS, a set of VMs to be backed up from the plurality of VMs that yields a maximum performance for the backup request without causing the set of VM servers to become bottlenecked, wherein the determination is performed based on at least one of a concurrency limit of the virtual backup appliance (VBA) and any VBA proxies corresponding to the set of VMs, and a set of one or more data performance metrics of one or more storage devices in the set of VM storage arrays, and sending one or more backup jobs to the VBA to back up the determined set of VMs to be backed up to a backup storage system.

Abstract: A database management server manages a distributed data set at least partially stored in volatile memory of a plurality of nodes. The database management server stores transaction logs in persistent storage corresponding to one or more database transactions performed on the distributed data set. In response to a query, a join operation is performed with assistance from the cluster. A snapshot identifier identifies a particular database state that is transactionally consistent. Based on the transactional logs, updated data blocks updated after the snapshot identifier of the query are identified. The cluster is instructed to perform one or more distributed join operations on the distributed data set without processing data in the updated data blocks. The database management server performs a partial join evaluation on the updated data blocks.

Abstract: A technique manages host data in a data storage array. The technique involves placing, in response to host input/output (I/O) requests from a set of host devices, host data in a container file system which is stored in a slice pool of storage slices (e.g., storage space of a standard size such as 256 MB) formed by multiple storage tiers of the data storage array. Each storage tier provides storage access at a different storage access speed. The technique further involves assigning classifications to storage slices of the slice pool which store the container file system, each classification being assigned based on storage slice access history resulting from the host I/O requests. The technique further involves relocating portions of the container file system among the multiple storage tiers according to the classifications assigned to the storage slices of the slice pool.

Abstract: A continuous stream data (e.g., messages, tweets) is received by ingest nodes of a platform. The ingest nodes may analyze the data to create a transaction of graph updates, assign a sequence number to the transaction, and distribute the graph updates with the sequence number to graph nodes of the platform. The graph nodes may store graph updates from ingest nodes, and then the ingest nodes may report graph update progresses in a progress table. A snapshot may be taken based on the progress table, and then graph-mining computation may be implemented. Tolerate failures and decaying may be supported and incremental expansion may be allowed to cope with increasing update rates and computation needs.

Abstract: A method, system and computer program product for optimizing cloud resources in utilizing a pool of virtual machines to service user workloads. A writeable partition is created to store middleware and user activity associated with a virtual machine obtained from a pool of available virtual machines to be deployed. In response to the obtained virtual machine being terminated, the contents of the created writeable partition are erased so that the data generated by the middleware and user activity will not be available for subsequent users. The virtual machine is later returned to the pool of available virtual machines after resetting its password and network address to a default state. In this manner, fewer cloud resources are used since resource intensive activities that were required in provisioning a new virtual machine can be eliminated since previously terminated virtual machines can be utilized in the pool of available virtual machines.

Abstract: Systems and methods method enabling file actions to be performed on a folder structure in a cloud-based service are disclosed. In one aspect, embodiments of the present disclosure include a method, which may be implemented on a system, for representing the folder structure in a user interface to the cloud-based service as a file and enabling file actions to be performed on file representing the folder structure in the user interface to the cloud-based service. In one embodiment, the folder structure and associated content is stored on a server which provides the cloud-based service in a compressed file format which is able to preserve the metadata associated with the folder structure which indicates its representation as the file in the user interface.

Abstract: Example apparatus and methods process virtual machine image level backups that may include files that are compressed and files that are not compressed. Example apparatus and methods may produce virtual machine image level backups by selectively compressing some files associated with the image while leaving other files in their uncompressed state. Example apparatus and methods may selectively recover a file or even an entire disk image from an image level backup that may include both compressed files and files that are not compressed. The file recovery or image recovery may be performed at the file level by accessing files in the image and selectively decompressing files that are compressed in the image while passing through files that are not compressed in the image. Different files in a single image may be compressed or decompressed using different techniques.

Abstract: Archiving a database and point in time recovery of the database. A method includes taking a first snapshot of a database. The first snapshot of the database includes a first snapshot of the data in the data storage and a first snapshot of the log records in the log storage. The method further includes taking a second snapshot of the database. The second snapshot of the database includes a second snapshot of the data in data storage and a second snapshot of the log records. The method further includes restoring the database to a particular point by applying the first snapshot of the data in the data storage to the database, applying the first snapshot of the log records in the log storage to the database and applying a portion of the second snapshot of the log records in the log storage to the database.

Abstract: An administrator provisions a virtual disk in a remote storage platform and defines policies for that virtual disk. A virtual machine writes to and reads from the storage platform using any storage protocol. Virtual disk data within a failed storage pool is migrated to different storage pools while still respecting the policies of each virtual disk. Snapshot and revert commands are given for a virtual disk at a particular point in time and overhead is minimal. A virtual disk is cloned utilizing snapshot information and no data need be copied. Any number of Zookeeper clusters are executing in a coordinated fashion within the storage platform, thus increasing overall throughput. A timestamp is generated that guarantees a monotonically increasing counter, even upon a crash of a virtual machine. Any virtual disk has a “hybrid cloud aware” policy in which one replica of the virtual disk is stored in a public cloud.

Abstract: A method and apparatus for performing granular restoration from machine images stored on sequential backup media is disclosed. In one embodiment, the method for performing granular restoration from machine images stored on sequential backup media includes processing at least one machine image file to identify at least one database file and at least one data object that is arranged within the at least one database file and generating mapping information regarding the at least one data object within the at least one machine image file, wherein the at least one machine image is to be stored on the sequential backup media.

Abstract: A service provider system may include an application fulfillment platform that delivers desktop applications on demand to desktops on physical computing devices or virtual desktop instances of end users. An application delivery agent installed on an end user's computing resource instance may store application state data (e.g., configuration data, runtime settings, or application templates) or scratch data that is generated by an application executing on the computing resource instance to a secure location on service provider storage resources. After a machine failure or change, or a rebuilding of a virtualized computing resource instance or virtual desktop instance, an application delivery agent installed on the new machine or instance may reinstall the application, retrieve the stored application state or scratch data from service provider resources, and restore the application to the last known persisted state.

Abstract: An illustrative approach to managing snapshots streamlines how and when snapshots are generated in a storage management system, such that fewer snapshots may be generated without diminishing the scope of data protection. A novel unified-snapshot storage policy may govern snapshots for any number of subclients. A unified-snapshot job based on the unified-snapshot storage policy enables the illustrative storage management system to automatically discover relevant components and generate at most one snapshot per target logical unit number (“LUN”) in a storage array. Each snapshot may comprise the data of any number of subclients and/or clients in the storage management system. Accordingly, one unified-snapshot job may yield a minimum but sufficient number of snapshots comprising data of all subclients associated with the governing unified-snapshot storage policy. An enhanced storage manager may manage the unified-snapshot jobs.

Abstract: Method and apparatus for managing a memory, such as but not limited to a flash memory. In accordance with some embodiments, user data and associated metadata are stored in a memory. The metadata are arranged as a first sequence of snapshots of the metadata at different points in time during the operation of the memory, and a second sequence of intervening journals which reflect updates to the metadata from one snapshot to the next. Requested portions of the metadata are recovered from the memory using a selected snapshot in the first sequence and first and second journals in the second sequence.

Abstract: Exemplary methods for verifying data integrity for garbage collection with limited memory include maintaining a data structure that includes a plurality of entries, storing states of a group of segments compressed therein. In response to receiving a request for transitioning a segment from a first state to a second state, retrieving a first entry value of an entry associated with the first segment, generating a second entry value based on the first entry value, the first state, the second state, and a value obtained from a first lookup table based on the first segment. The methods also include writing back the second entry value to the first entry of the data structure. In one embodiment, in response to determining all entries of the data structure reach a predetermined final state, performing a garbage collection process on the segments stored in the storage system.

Abstract: A system that implements a data storage service may maintain tables in a data store on behalf of clients. The service may maintain table data in multiple replicas of partitions of the data that are stored on respective computing nodes in the system. In response to detecting a failure or fault condition, or receiving a service request from a client to move or copy a partition replica, the data store may copy a partition replica to another computing node using a physical copy mechanism. The physical copy mechanism may copy table data from physical storage locations in which it is stored to physical storage locations allocated to a destination replica on the other computing node. During copying, service requests to modify table data may be logged and applied to the replica being copied. A catch-up operation may be performed to apply modification requests received during copying to the destination replica.

Abstract: Detecting modifications to a storage that occur in an alternate operating environment. In one example embodiment, a method for detecting modifications to a storage that occur in an alternate operating environment may include tracking, in a modify map, modifications to a storage that occur during operation of a primary operating environment, identifying a first most recent transaction identifier in a journal of a file system of the storage prior to closing of the storage by the primary operating environment, upon opening of the storage by the primary operating environment, identifying a second most recent transaction identifier in the journal, determining that the second most recent transaction identifier does not match the first most recent transaction identifier, concluding that the storage was modified in an alternate operating environment between the closing and the opening of the storage by the primary operating environment, and invalidating the modify map.

Abstract: Systems and methods which provide an absent allocation technique with respect to absent data of a data structure for which data migration in a time-displaced data migration operation has not completed are disclosed. Through use of absent allocated data block states of an absent allocation technique of embodiments, dependency between source and destination data stores may be broken. An absent allocated data block state of embodiments stored within the data structure provides a suggestive indication that data of a data block of a data structure is absent from the data structure. A corresponding absent allocated data block state of embodiments stored external to the data structure provides a determinative indication that the data of the data block of the data structure is absent from the data structure. The absent data block determinative indictor of embodiments is updated as data continues to be migrated.

Abstract: A method, system, and computer program product comprising using a tracking structure to map a first portion and a second portion of a non-volatile storage medium to a logical representation of the non-volatile storage medium; wherein the first portion is presented by the logical representation as writable storage and using the tracking structure to enable the logical representation to present the data written to the second portion as the data corresponding to the write in the first portion.

Abstract: A solution for validating a set of data protection solutions is provided. A validation scenario can be defined, which can include data corresponding to a set of attributes for the validation scenario. The attributes can include a time frame for the validation scenario. The validation scenario also can include a set of backup images to be validated, each of which is generated using one of the set of data protection solutions. The set of backup images can be identified using the time frame. A set of resource requirements for implementing the validation scenario can be determined based on the set of backup images and the set of attributes for the validation scenario.

Abstract: A file storage system for storing data of a file received from a client includes a back-end file server in which the data is stored. The system includes a cache appliance in communication with the file server, such that the appliance stores portions of the data or attributes of the file, and uses the stored data or attributes to process file system requests received from the client, and which reads and writes data and attributes to the back-end file server independently. A system for responding to a file system protocol request in regard to a back-end server includes a token server.

Abstract: Systems and methods for resuming data transformations, such as broken or otherwise unsuccessful data transformations, are described. In some example embodiments, the systems and methods receive a message that indicates a broken data transformation of a data table between a source database and a destination database, identify a maximum and/or largest and greatest value for a date attribute contained within an index column for all rows of the data table that were successfully loaded to the destination database during the data transformation, and select a group of rows of data of the data table stored in the source database by querying the source database to identify rows that include a value for the date attribute that is greater than the identified value.

Abstract: Aspects of the present invention provide a solution for passively monitoring a computer system. In an embodiment, an indexing agent operates on a physical server having a plurality of virtual servers. The indexing agent has a framework having a plurality of indexing layers. Each of these indexing layers is adapted to index a virtual server along a different abstraction level to extract abstraction level features indicative of changes in the virtual server. Further, each of the indexing layers has an application programming interface, which is adapted to receive one or more external indexing modules to be plugged into the framework. Each indexing module is adapted to provide instructions to the indexing agent while the indexing layer to which it is plugged is indexing the associated abstraction level of the virtual machine.