Logical volume manager and method having enhanced update capability with dynamic allocation of storage and minimal storage of metadata information
First Claim
1. In a programmed, general purpose digital computer having a memory and coupled to data storage devices, a logical volume manager having computer software operative for:
- creating a logical unit of undivided storage;
allocating portions of said data storage devices to said logical unit of undivided storage;
storing metadata on said data storage devices containing information about portions of said data storage devices that have been allocated to said logical unit of undivided storage;
automatically changing the size of said logical unit of undivided storage whereby portions of said data storage devices are allocated to or deallocated from said logical unit of undivided storage; and
updating said metadata after automatically changing the size of said logical unit of undivided storage and only on said data storage devices affected by the automatic change of size.
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Accused Products
Abstract
An apparatus, a method, and a computer program product conceptually provide a logical unit of undivided data storage that spans physical storage device boundaries. The apparatus manages the logical unit of undivided storage using metadata information stored on the physical storage devices. Advantageously, the apparatus replicates a minimum portion of the metadata information across all of the data storage devices and favors writing metadata only in the devices where the information is required to operate. In a preferred embodiment, a logical unit of undivided storage is created by defining a logical volume and allocating portions of available physical data storage devices thereto in order to provide a minimum logical volume size. Metadata is generated and stored on the data storage devices to provide detailed information about the portions of each data storage device that have been allocated to the logical volume. After initialization, the size of the logical volume can be automatically changed such that portions of the data storage devices are allocated to or deallocated from the logical volume. Following an allocation or deallocation operation, the metadata stored on the data storage devices is minimally updated only on the data storage devices affected by the operation. The metadata on unaffected storage devices is not changed such that processing time is improved. In another embodiment, the metadata may be differentiated into two types, global and local. Global metadata is maintained in a fully replicated way across all of the data storage devices. Local metadata containing information specific to a particular data storage device is maintained on that storage device but is not replicated on other storage devices. In this way, data storage space availability is improved. In still another embodiment, an in-memory data structure is constructed to maintain information derived from the stored local metadata. Full operation is possible despite failed or unavailable physical data storage devices.
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Citations
30 Claims
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1. In a programmed, general purpose digital computer having a memory and coupled to data storage devices, a logical volume manager having computer software operative for:
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creating a logical unit of undivided storage; allocating portions of said data storage devices to said logical unit of undivided storage; storing metadata on said data storage devices containing information about portions of said data storage devices that have been allocated to said logical unit of undivided storage; automatically changing the size of said logical unit of undivided storage whereby portions of said data storage devices are allocated to or deallocated from said logical unit of undivided storage; and updating said metadata after automatically changing the size of said logical unit of undivided storage and only on said data storage devices affected by the automatic change of size. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method for managing logical volumes executed by a programmed, general purpose digital computer having a memory and coupled to data storage devices, said method comprising the steps of:
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creating a logical unit of undivided storage; allocating portions of said data storage devices to said logical unit of undivided storage; storing metadata on said data storage devices containing information about portions of said data storage devices that have been allocated to said logical unit of undivided storage; automatically changing the size of said logical unit of undivided storage whereby portions of said data storage devices are allocated to or deallocated from said logical unit of undivided storage; and updating said metadata following operation of said step of automatically changing the size of said logical unit of undivided storage, said step of updating said metadata operating only on said data storage devices affected by said step of automatically changing the size of said logical unit of undivided storage. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. A computer program product for use in a programmed, general purpose digital computer having a memory and coupled to data storage devices, said computer program product comprising:
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a data storage medium; software recorded on said data storage medium and executable for creating a logical unit of undivided storage; software recorded on said data storage medium and executable for allocating portions of said data storage devices to said logical unit of undivided storage; software recorded on said data storage medium and executable for storing metadata on said data storage devices containing information about portions of said data storage devices that have been allocated to said logical unit of undivided storage; software recorded on said data storage medium and executable for automatically changing the size of said logical unit of undivided storage whereby portions of said data storage devices are allocated to or deallocated from said logical unit of undivided storage; and software recorded on said data storage medium and executable for updating said metadata after automatically changing the size of said logical unit of undivided storage and only on said data storage devices affected by the automatic change of size. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29, 30)
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Specification