Method and system for continuous data protection
View Patent ↗Continuous data protection is performed as two parallel processes: copying a data block from the storage device into the backup storage device (creating initial backup) and copying the data block to be written to the data storage into the incremental backup. When a write command is directed to a data storage block, it's intercepted and redirected to the backup storage, and data, which is to be written in accord to the write request, is written to the incremental backup on the backup storage. If write command is also directed to a data storage block identified for backup that has not yet been backed up, the identified data storage block is copied from the storage device to the intermediate storage device, the write command is executed on the identified data storage block from the storage device, and the data storage block is copied from the intermediate storage device to the backup storage device. In case of an error accessing a block on the storage device, the block is marked as invalid. The system suspends a write command to the storage device during the initial data backup process if the intermediate storage device has reached a selected data capacity; and copies a selected amount of data from the intermediate storage device to the backup storage device.
1. A computer system providing online continuous data protection, the computer system comprising:
a storage device storing block data;
a backup storage device storing block data; and
wherein the computer system is operable to:
creating a single bitmap of data storage blocks on the storage device that are subject to an initial backup;
copying blocks marked in the bitmap as an initial backup to the backup storage device;
in case of error when accessing the storage device, indicating in the bitmap, that the data storage block that caused the error is invalid;
creating an editable incremental backup on the backup storage device, such as that any block in the editable incremental backup is subject to being rewritten so long as the editable incremental backup is open; and
during the creation of the editable incremental backup, intercepting a write command directed to a data storage block marked in the bitmap and redirecting the write command to the editable incremental backup on the backup storage device, and
for data that is to be written in the write command, writing the data to editable incremental backup on the backup storage by executing the redirected write command,
wherein, if the data block that is the subject of the write command was backed up in a latest incremental backup, replacing the old data block in the latest incremental backup with the data block that is the subject of the write command,
wherein the latest incremental backup reflects latest changed data on the data storage device; and
after intercepting the write command, duplicating the write command on the data storage device.
2. The computer system of claim 1 , further comprising creating a new incremental backup when a previous incremental backup is closed and not subject to editing.
3. The computer system of claim 1 , wherein the computer system is further operable to restore the backed up data to the storage device from the current incremental backup.
4. The computer system of claim 1 , wherein the computer system is further operable to restore the backed up data to the storage device from any previous incremental backup.
5. The computer system of claim 4 , wherein the restoring is performed over a network.
6. The computer system of claim 1 , wherein an intermediate block data container is used to store data that has not yet been backed up, wherein the computer system is operable to write a data block from the data storage device into the intermediate block data container and to then copy that data block from the intermediate block data container into the backup storage device.
7. The computer system of claim 1 , wherein the incremental backup is opened for editing.
8. The computer system of claim 1 , wherein the computer system is operable to:
suspend a write command to the data storage device if the intermediate block data container has reached a selected data capacity; and
copy a selected amount of data from the intermediate block data container to the backup storage device.
9. A method for providing continuous data protection for data stored on a data storage device of a computer system, the method comprising the steps of:
creating a single bitmap of data storage blocks on the storage device that are subject to an initial backup;
copying blocks marked in the bitmap as an initial backup to the backup storage device;
in case of error when accessing the storage device, indicating in the bitmap that the data storage block that caused the error is invalid;
creating an editable incremental backup on the backup storage device, such as that any block in the editable incremental backup is subject to being rewritten so long as the editable incremental backup is open; and
during the creation of the editable incremental backup, intercepting a write command directed to a data storage block marked in the bitmap and redirecting the write command to the editable incremental backup on the backup storage device; and
for data that is to be written in the write command, writing the data to the editable incremental backup on the backup storage by executing the redirected write command,
wherein, if the data block that is the subject of the write command was backed up in a latest incremental backup, replacing the old data block in the latest incremental backup with the data block that is the subject of the write command,
wherein the latest incremental backup reflects latest changed data on the data storage device; and
after intercepting the write command, duplicating the write command on the data storage device.
10. The method of claim 9 , further comprising creating a new incremental backup when a previous incremental backup is closed and not subject to editing.
11. The method of claim 9 , further comprising restoring the backed up data to the storage device from the current incremental backup.
12. The method of claim 9 , further comprising restoring the backed up data to the storage device from any previous incremental backup.
13. The method of claim 12 , wherein the restoring is performed over a network.
14. The method of claim 9 , wherein an intermediate block data container is used to store data that has not yet been backed up, wherein the computer system is operable to write a data block from the data storage device into the intermediate block data container and to then write that data block from the intermediate block data container into the backup storage device.
15. The method of claim 9 , wherein the incremental backup is an opened for editing.
16. The method of claim 9 , further comprising:
suspending a write command to the data storage device if the intermediate block data container has reached a selected data capacity; and
writing a selected amount of data from the intermediate block data container to the backup storage device.
17. A non-transitory computer useable storage medium having computer executable program logic stored thereon for executing on a processor, the computer executable program logic including a computer program code adapted to perform the method of claim 9 .