摘要:
A remote data shadowing system provides storage based, real time disaster recovery capability. Record updates at a primary site cause write I/O operations in a storage subsystem therein. The write I/O operations are time stamped and the time, sequence, and physical locations of the record updates are collected in a primary data mover. The primary data mover groups sets of the record updates and associated control information based upon a predetermined time interval, the primary data mover appending a prefix header to the record(updates thereby forming self describing record sets. The self describing record sets are transmitted to a remote secondary site wherein consistency groups are formed such that the record updates are ordered so that the record updates can be shadowed in an order consistent with the order the record updates cause write I/O operations at the primary site.
摘要:
A multi-session data storage facility coordinates similar status changes across all sessions at appropriate times. In each session, a data mover implements data mirroring by copying updates from the primary storage to the secondary storage. A master data set, accessible by all sessions, includes a common area for posting commands and/or errors to all sessions and individual session areas for posting errors occurring in particular sessions. When a data mover receives a host initiated command, this data mover becomes a “master.” Initially, the master data mover lists the command in the master data set's common area. Whenever other, “slave” data movers notice a command in the master data set's common area, they respond by suspending their formation of consistency groups and responding with a “ready” message. The “ready” message comprises the slave data mover's consistency form time (i.e., the earliest of most-recent update time from all controllers in that session). Accordingly, after posting the command, the master data mover reviews the slave data movers' responses. If these responses indicate all sessions can execute the command at a requested consistent time, then the master data mover instructs the slave data movers to execute the command by entering an execute instruction in the master data set's common area. Otherwise, the master data mover enters a cancel operation in the master data set's common area.
摘要:
A system, method, and program for maintaining data consistency among updates to data storage areas are provided. Each update has an update time the update was made. There are multiple groups of data storage areas. For each group, updates to the data storage area in the group are stored in a journal for storing updates to the group, wherein there are multiple journals. An indication is made in a memory area for each group of a group update time comprising a most recent update time of the updates in the group. The update time for each update in the group is not greater than the group update time. A determination is made of a minimum group update time across all the groups. At least one update is applied to storage if the update time for the update does not exceed the minimum group update time. The data storage areas may be partitioned among a plurality of computer systems, and may be maintained in at least one primary and secondary storage. The data storage areas may also comprise volumes, with each group including at least one volume. The groups of updates may also be maintained in a journal.
摘要:
In a system including a host, a primary storage subsystem coupled to the host, a cache coupled to the host and separate from the primary storage system, a secondary storage subsystem, and a data mover coupling the primary and secondary storage systems, data is temporarily cached for future storage in the primary storage subsystem so as to preserve timestamp information and maintain data consistency for asynchronously mirroring the data at a secondary subsystem.
摘要:
Disclosed is a system for managing pages in a volatile memory device for data transfer operations between a first storage area and a second storage area. The first storage area is queried to determine a number of data sets to include in a data transfer operation. A number of pages in the volatile memory device needed for the data transfer operation is then determined. A determination is then made as to whether the number of pages needed for the data transfer operation is greater than available fixed pages in a pool of pages. Available fixed pages in the pool are allocated to the data transfer operation after determining that the number of pages needed to process the data transfer operation is less than or equal to the available fixed pages in the pool. Alternatively, after determining that the number of pages needed to process the data transfer operation is greater than the available fixed pages in the pool, all the fixed pages in the pool and additional fixed pages are allocated to the data transfer operation.
摘要:
Data is stored in one or more data storage devices, the number of active data storage devices being adaptively adjusted to maximize parallelism while minimizing device overhead. Multiple datasets are first received, these being designated for storage in multiple data storage devices. Next, a first one of the received datasets is stored in a first one of the data storage devices. Concurrently with storage of the first dataset, the following steps are performed: (1) selecting a second received dataset from those remaining to be stored, (2) selecting an available data storage device by employing a predetermined criteria, and (3) beginning storage of the second dataset in the selected data storage device. The predetermined criteria for selecting an available data storage device may involve, for example, selecting an available device based on a "first fit" or a "best fit" scheme. Concurrently with storage of the second dataset, storage of a third dataset starts. Likewise, the process of storing each subsequent dataset commences while the previous dataset is being stored. This technique promotes efficiency, since later-received datasets may be stored in previously used storage devices that have already finished storing earlier datasets. Accordingly, less processing overhead is occupied in activating previously dormant data storage devices.
摘要:
Backup storage is resynchronized to primary storage, ensuring that any new updates received during resynchronization are applied in the proper order relative to resynchronization data. Under normal operations, a data mover mirrors data stored in primary storage to backup storage. If an error condition arises, preventing mirroring, the data mover stores newly received data in primary storage without mirroring the data to backup storage. The data mover also identifies this data in an update map. When the error condition ends, the data mover performs a static resynchronization process, serving to update the backup storage with the un-mirrored data, identified in the update map. When new data is received during static resynchronization, a dynamic resynchronization process is invoked to accurately process the updates. Dynamic resynchronization ensures that newly received data records are copied to backup storage in the proper order (if at all) with respect to versions of the same data being processed by static resynchronization.
摘要:
A method, apparatus, and article of manufacture for dynamic change management in an extended remote copy system. A primary data mover monitors changes made to a primary data volume resulting from write I/O operations, wherein the changes are reflected in a data structure maintained by the primary data mover. The primary data mover performs a multi-level analysis on the data structure to discard a portion of the changes therein, so that the changes that have been applied to a secondary data volume are discarded from the data structure and the changes that have not been applied to the secondary data volume are maintained in the data structure.
摘要:
Backup storage is resynchronized to primary storage, ensuring that any new updates received during resynchronization are applied in the proper order relative to resynchronization data. Under normal operations, a data mover mirrors data stored in primary storage to backup storage. If an error condition arises, preventing mirroring, the data mover stores newly received data in primary storage without mirroring the data to backup storage. The data mover also identifies this data in an update map. When the error condition ends, the data mover performs a static resynchronization process, serving to update the backup storage with the un-mirrored data, identified in the update map. When new data is received during static resynchronization, a dynamic resynchronization process is invoked to accurately process the updates. Dynamic resynchronization ensures that newly received data records are copied to backup storage in the proper order (if at all) with respect to versions of the same data being processed by static resynchronization.
摘要:
A primary data mover monitors both consistency time and idle time in a system that performs continuous, asynchronous, extended remote copying between primary and remote processors, and manages both with accuracy and consistency. The primary data mover detects system activity levels and manages data accuracy for the extended remote copying in both active and idle systems.