Continuous data backup
Handling writing new data includes creating a journal entry that points to a first storage location containing old data to be replaced by the new data, where the journal entry is maintained after writing the new data, allocating new storage space having a second storage location, and writing the new data to the new storage space at the second storage location. The storage space may be provided by at least one storage device. Allocating new storage space may include remapping a switch coupled to the at least one storage device. The new data may be written by a host coupled to the switch. The switch may present the host with a logical storage area that is created by the switch mapping to different locations of the at least one storage device. The mapping may be transparent to the host. The switch may include at least one processor and a corresponding memory. The journal entry may be part of a journal that is stored in the memory. The storage space may correspond to a disk array storage device. The journal entry may be stored in the disk array storage device. The journal entry may be stored outside the disk array storage device. Allocating new storage space may include remapping a switch coupled to the disk array storage device and where the journal entry is stored on the switch. Each of the journal entries also includes a time stamp and/or a result of writing the data.
1. A switch, comprising:
a plurality of input ports;
a plurality of output ports; and
at least one backplane interposed between the input ports and the output ports, wherein said backplane selectively connects input ports and output ports to provide that, in response to new data being written at one of the input ports, a journal entry that is maintained after the new data is written is created to point to a first storage location on storage space coupled to the output ports, the first storage location pointing to old data that corresponds to and is older than the new data, new storage space having a second storage location is allocated and the new data is written to the new storage space at the second storage location, wherein the old data is maintained in the storage space at the first storage location after the new data is written to the new storage space at the second storage location.
2. The switch, according to claim 1 , further comprising:
a memory that is part of the backplane, wherein the journal entry is stored in the memory.
3. The switch, according to claim 2 , wherein the journal entry is part of a journal that is stored in the memory.
4. The switch, according to claim 1 , further comprising:
a processor that is disposed within the backplane.
5. The switch, according to claim 4 , wherein the processor includes executable code that causes the switch to create the journal entry and to allocate the new storage space.
6. The switch, according to claim 1 , wherein the storage space is provided by at least one storage device.
7. The switch, according to claim 6 , wherein allocating new storage space includes remapping the switch coupled to the at least one storage device.
8. The switch, according to claim 7 , wherein the new data is written by a host coupled to the switch.
9. The switch, according to claim 8 , wherein the switch presents the host with a logical storage area that is created by the switch mapping to different locations of the at least one storage device.
10. The switch, according to claim 8 , wherein the mapping is transparent to the host.
11. The switch, according to claim 1 , wherein the storage space corresponds to a disk array storage device.
12. The switch, according to claim 11 , wherein the journal entry is stored in the disk array storage device.
13. The switch, according to claim 11 , wherein the journal entry is stored outside the disk array storage device.
14. The switch, according to claim 1 , wherein each of the journal entries also includes a time stamp.
15. The switch, according to claim 1 , wherein each of the journal entries also includes a result of writing the data.
16. A data storage device, comprising:
at least one disk drive that contains data;
at least one host adaptor, coupled to the at least one disk drive, that receives data to be stored on the at least one disk drive; and
computer software that handles writing new data, wherein the computer software includes executable code that creates a journal entry that points to a first storage location containing old data that corresponds to and is older than the new data, wherein the journal entry is maintained after writing the new data, executable code that allocates new storage space having a second storage location, and executable code that writes the new data to the new storage space at the second storage location, wherein the old data is maintained at the first storage location after the new data is written to the new storage space at the second storage location.
17. The data storage device, according to claim 16 , wherein allocating new storage space includes remapping a switch coupled to the data storage device.
18. The data storage device, according to claim 17 , wherein the switch is a logical storage area that is created by the switch mapping to different locations of the data storage device.
19. The data storage device, according to claim 16 , wherein each of the journal entries also includes a time stamp.
20. The data storage device, according to claim 16 , wherein each of the journal entries also includes a result of writing the data.