204 results about "Copy-on-write" patented technology

According to one embodiment, a computerized method comprises operations of instantiating a first virtual machine instance and a second virtual machine instance to run concurrently with the first virtual machine instance. The first virtual machine instance provides a first virtual operating environment while the second virtual machine instance is adapted to share the resources allocated to the first virtual machine instance. The second virtual machine instance is further adapted to allocate additional resources upon conducting a Copy-On Write operation.

A system, method and computer program product for managing files of Virtual Machines, including launching a plurality of Virtual Machines in a computing system having a host OS; using a content of at least one file of the host OS as a shared file; using a re-direct, providing access to the shared file when any Virtual Machine attempts to access its private file; using copy-on-write, making a copy of the shared file if the Virtual Machine attempts to modify the shared file, and placing a copy of the shared file in a private area of the corresponding Virtual Machine.

Upon occurrence of a trigger condition, writes of allocation units of data (including code) to a device, such as writes of blocks to a disk, are first encrypted. Each allocation unit is preferably a predetermined integral multiple number of minimum I / O units. A data structure is marked to indicate which units are encrypted. Upon reads from the device, only those allocation units marked as encrypted are decrypted. The disk protected by selective encryption is preferably the virtual disk of a virtual machine (VM). The trigger condition is preferably either that the virtual disk has been initialized or that the VM has been powered on. Mechanisms are also provided for selectively declassifying (storing in unencrypted form) already-encrypted, stored data, and for determining which data units represent public, general-use data units that do not need to be encrypted. The “encrypt-on-write” feature of the invention may be used in conjunction with a “copy-on-write” technique.

On demand image streaming (ODS), in one aspect, may perform both copy-on-write and copy-on-read to gradually bring data on remote storage server to a host's local disk. Prefetching may be performed during the time the resources are otherwise idle to bring in data from the remote storage server to the host's local disk. A new image format and the corresponding block device driver for a hypervisor or the like may be also provided. ODS' image format may include a header and a bitmap that indicates whether the data sectors are on local disk or remote storage server, and an image content, for instance, stored in raw format.

A computer system has one or more software contexts that share use of a memory that is divided into units such as pages. In the preferred embodiment of the invention, the contexts are, or include, virtual machines running on a common hardware platform. The contents, as opposed to merely the addresses or page numbers, of virtual memory pages that are accessible to one or more contexts are examined. If two or more context pages are identical, then their memory mappings are changed to point to a single, shared copy of the page in the hardware memory, thereby freeing the memory space taken up by the redundant copies. The shared copy is then preferably marked copy-on-write. Sharing is preferably dynamic, whereby the presence of redundant copies of pages is preferably determined by hashing page contents and performing full content comparisons only when two or more pages hash to the same key.

The present invention is an optimized method for the rollback of copy-on-write snapshot volumes. A method in accordance with the present invention may comprise the following steps: (a) creating a copy-on-write snapshot volume; (b) receiving a base volume write request addressed to a base volume data block; (c) executing copy-on-write operations; (d) receiving a snapshot volume rollback request; (e) disabling the copy-on-write operations; and (f) executing volume copy operations.

A mutable multilevel data structure representing a graph structure may include multiple read-only levels and a single writable level. Each read-only level may include a vertex table (which includes references to edge tables on the same level or a different level containing elements of adjacency lists for some vertices) and an edge table (which includes elements of adjacency lists that changed since the previous read-only level). A hybrid variant may switch between a performance-optimized variant (whose edge tables include complete adjacency lists for vertices whose edge sets were modified) and a space-optimized variant (whose edge tables include only newly added adjacency list elements). The vertex tables and / or the writable level may be implemented using copy-on-write arrays, each including an indirection table and multiple fixed-sized data pages. Computations may be run on the read-only levels or on the writable level and read-only levels.

A logic volume snapshot copy management method used for a logic volume manager. When there is a data write-in request, the plurality of snapshot copies established in the logic volume corresponding to the various time points are utilized to search in the logic volume for the data address of the data to be written. Then the data are copied into the snapshot copy of the last time point, at the data address of the data to be written in the logic volume, by Copy-On-Write (COW) operation. When there is a snapshot copy read request, the snapshot copy data at the requested data address is to be retrieved. Through the method, the function of a high-speed snapshot copy can be realized. In addition, the storage space used for a snapshot copy can be reduced.

A system for disaster recovery rehearsals using copy-on-write may include a data set of an application and a disaster recovery manager. The disaster recovery manager may be configured to perform a disaster recovery rehearsal using a copy-on-write snapshot of the data set.

Upon occurrence of a trigger condition, writes of allocation units of data (including code) to a device, such as writes of blocks to a disk, are first encrypted. Each allocation unit is preferably a predetermined integral multiple number of minimum I / O units. A data structure is marked to indicate which units are encrypted. Upon reads from the device, only those allocation units marked as encrypted are decrypted. The disk protected by selective encryption is preferably the virtual disk of a virtual machine (VM). The trigger condition is preferably either that the virtual disk has been initialized or that the VM has been powered on. Mechanisms are also provided for selectively declassifying (storing in unencrypted form) already-encrypted, stored data, and for determining which data units represent public, general-use data units that do not need to be encrypted. The “encrypt-on-write” feature of the invention may be used in conjunction with a “copy-on-write” technique.

The invention provides an improved method and apparatus for creating a snapshot of a file system. A “copy-on-write” mechanism is used. The snapshot uses the same blocks as the active file system until the active file system is modified. Whenever a modification occurs, the modified data is copied to a new block and the old data is saved. In this way, the snapshot only uses space where it differs from the active file system, and the amount of work required to create the snapshot is small. A record of which blocks are being used by the snapshot is included in the snapshot itself, allowing effectively instantaneous snapshot creation and deletion. A snapshot can also be deleted instantaneously simply by discarding its root inode.

A copy method is disclosed to provide a duplicate copy of source data where the duplicate copy is consistent with the source data as of a designated time. The method includes creating a copy-on-write relationship between specified source data and an original image cache, utilizing an application outboard of the designated host application to copy all items of source data and their associated locations to a secondary data object without regard to whether the items source data have been updated since creating the copy-on-write relationship, and copying a specified amount of contents of the original image cache to the secondary data object. The specified amount includes contents of the original image cache as of completion of the utilizing operation. In addition, the method includes permitting copy-on-write relationship to continue during the utilizing operation and during at least part of the copying operation.

Providing a snapshot copy of data includes selectively collecting a plurality of data objects based on evaluation of a predicate associated with each of the data objects and performing a snapshot operation in connection with modifying at least one of the plurality of data objects. The snapshot operation may be performed prior to modifying the at least one of the plurality of data objects. The snapshot operation may be a copy on write operation. Providing a snapshot copy of data may also include providing a data structure that maintains a plurality of snapshot instances. The data structure may be a table. Each of the snapshot instances may include at least one of: an object set description, a timestamp indicating when the snapshot was initiated, a snapshot name and a handling policy.

The invention discloses a method and a device for processing metadata. The method comprises the following steps of: copying data written for the first time in an original disk space into a snapshot backup data area according to copy-on-write operation, establishing metadata and bitmap corresponding relationships and calculating a first address of a metadata bitmap area where the metadata belongs and metadata position indexes of the metadata in the metadata bitmap area according to the bitmap corresponding relationships; judging whether the first address is the same as a preset allocation marker bit or a deletion marker bit or not to obtain a comparison result and setting bitmap mapping bits; and according to the comparison result, the first address of the metadata bitmap area where the metadata belongs, and the metadata position indexes, storing the metadata into corresponding position indexes of an allocation control buffer area or a deletion control buffer area, or writing all the metadata in the allocation control buffer area into corresponding positions of the metadata bitmap area or deleting all the metadata in the deletion control buffer area from the corresponding positionsof the metadata bitmap area.