On-demand allocation of physical storage for virtual volumes using a zero logical disk
First Claim
1. A method for allocating physical storage, comprising:
- creating a virtual volume, the virtual volume comprising a virtual volume region storing a pointer to a zero logical disk, wherein the zero logical disk is not mapped to any physical storage;
receiving from a host a write request to the virtual volume;
mapping the write request to the virtual volume region;
mapping the virtual volume region to the zero logical disk;
in response to said mapping the virtual volume region to the zero logical disk, assigning a logical disk region to the virtual volume region, wherein the logical disk region is assigned to physical storage; and
writing to the logical disk region.
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Accused Products
Abstract
In one embodiment of the invention, a virtual volume is divided into “filled” and “empty” virtual volume (VV) regions. Empty VV regions are mapped to a special zero logical disk that does not consist of any physical disk regions. When a host writes to an empty VV region, a logical disk (LD) region is allocated to the empty VV region so the formerly empty VV region becomes a filled VV region mapped to the allocated LD region. If there are no LD regions available, a new logical disk is created. Additional physical storage can be added to the storage server to create new logical disks as the use of the virtual volume grows. Physical allocation warning points and limits allow the system administrator to be alerted to and to control physical allocation for each individual VV and the set of VVs drawing from the same data allocation control structure (DC).
65 Citations
9 Claims
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1. A method for allocating physical storage, comprising:
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creating a virtual volume, the virtual volume comprising a virtual volume region storing a pointer to a zero logical disk, wherein the zero logical disk is not mapped to any physical storage; receiving from a host a write request to the virtual volume; mapping the write request to the virtual volume region; mapping the virtual volume region to the zero logical disk; in response to said mapping the virtual volume region to the zero logical disk, assigning a logical disk region to the virtual volume region, wherein the logical disk region is assigned to physical storage; and writing to the logical disk region. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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Specification