Snapshots in a flash memory storage system
View Patent ↗A system and method of managing the storage of data in flash memory performs snapshots of the data by maintaining the data at the epoch that the snapshot is performed in the same physical memory location. Data that is modified after the snapshot is then stored to a new physical memory location and referenced to the snapshot location. When a user read operation is performed, the data is read from the original location if the read operation is for the snapshot data. The read operation for dynamic data is performed from the original location if the data has not change since the snapshot epoch, or from the referenced data location if the data has changed since the snapshot epoch. Snapshots are released by dereferencing the original location if the data has been changed since the snapshot epoch.
1. A memory system comprising:
a memory module, the memory module further comprising:
a memory controller;
a buffer memory;
a plurality of non-volatile memory circuits;
wherein the memory controller is configured to store data having a logical address in the plurality of the non-volatile memory circuits and for which a snapshot is performed at a first epoch such that a change to the data having a same logical address occurring after the first epoch, is stored in a memory circuit of the non-volatile memory circuit such that a read request for data at the same logical address for snapshot data is to the physical address where the data as of the first epoch is stored and a read request for dynamic data at the same logical address is to one of the physical address at which the data of the first epoch is stored if the data stored at the same logical address has not changed since the first epoch, or to a physical address at which the data is stored if the data stored at the same logical address has changed since the first epoch;
wherein a change to dynamic data at a logical address that occurs subsequent to the first epoch creates a link to a data structure pointing to the physical location at which the changed dynamic data is stored, while maintaining an association of the physical address of the dynamic data at the first epoch for the same logical block address, and the link is created when the dynamic data is changed.
2. A method of creating a snapshot of data, the method comprising:
providing a memory module, the memory module further comprising:
a memory controller;
a buffer memory;
a plurality of non-volatile memory circuits;
configuring the memory controller for:
storing data having a logical address, in the plurality of the non-volatile memory circuits at a first epoch, the logical address corresponding to a physical address in the non-volatile memory circuits;
determining that the data stored at the logical address has changed since the first epoch;
storing the changed data at another physical address from that associated with the data stored at the logical address at the first epoch;
maintaining an association between the data of the first epoch and the changed data such that a read request for data at the logical address for snapshot data is to the physical address where the data as of the first epoch is stored and a read request for dynamic data at the logical address is to one of the physical address at which the data of the first epoch is stored if the data stored at the logical address has not changed since the first epoch, or to a physical address at which the data is stored if the data stored at the logical address has changed since the first epoch,
wherein a change to dynamic data at a logical address that occurs subsequent to the first epoch creates a link to a data structure pointing to the physical location at which the changed dynamic data is stored, while maintaining an association of the physical address of the dynamic data at the first epoch for the same logical block address, and the link is created when the dynamic data is changed.
3. A computer program product, stored on a non-volatile memory, comprising:
configuring a controller to perform the steps of:
storing data having a logical address in a plurality of non-volatile memory circuits at a first epoch, the logical address corresponding to a physical address in the memory circuits;
determining that a change to the data stored at the logical address has change since the first epoch;
storing the changed data at another physical address from that associated with the data stored at the logical address at the first epoch;
maintaining an association between the physical locations of the data of the first epoch and the changed data such that a read request for data at the logical address for snapshot data is to the physical address where the data as of the first epoch is stored, and a read request for dynamic data at the logical address is to one of the physical address at which the data of the first epoch is stored if the data stored at the logical address has not changed since the first epoch, or to a physical address at which the data is stored if the data stored at the logical address has changed since the first epoch,
wherein a change to dynamic data at a logical address that occurs subsequent to the first epoch creates a link to a data structure pointing to the physical location at which the changed dynamic data is stored, while maintaining an association of the physical address of the dynamic data at the first epoch for the same logical block address and the link is created when the dynamic data is changed.