Method and apparatus for an application- and object-level I/O splitter
Example embodiments of the present invention relate to a method, an apparatus and a computer-program product for replicating logical level commands. The method comprises intercepting a logical level command at a splitter at a production site and creating a replica of the logical level command at the production site. The replica of the logical level command is then transmitted from the production site to a replication site.
1. A method comprising:
intercepting a logical level command at a splitter at a production site;
creating a replica of the logical level command at the production site;
transmitting the replica of the logical level command toward a replication site;
receiving the replica of the logical level command at the replication site;
writing the replica of the logical level command to a journal at the replication site; and
advancing a data storage state of the replication site forward to a particular data storage state at a particular point in time by reading logical level commands from a redo log of the journal and determining whether an inverse command for each of the logical level commands exists.
2. The method of claim 1 wherein the intercepted logical level command is selected from a group consisting of file system operations, database operations and block operations.
3. The method of claim 1 further comprising:
if an inverse command exists for each logical level command, then for each logical level command:
creating an inverse operation of the logical level command;
writing the inverse operation of the logical level command to an undo log of the journal;
applying the logical level command at the replication site; and
deleting the logical level command from the redo log.
4. The method of claim 1 further comprising:
if an inverse command does not exist for at least one logical level command:
taking a snapshot of the replication site;
storing the snapshot at the replication site; and
applying the logical level commands at the replication site.
5. The method of claim 1 further comprising restoring a data storage state of the replication site backward to a particular data storage state at a second particular point in time, comprising:
reading logical level commands from an undo log of the journal up to the second particular point in time; and
determining whether an inverse command for each of the logical level commands exists.
6. The method of claim 5 further comprising:
if an inverse command exists for each logical level command, then for each logical level command:
creating an inverse operation of the logical level command;
writing the inverse operation of the logical level command to a redo log of the journal;
applying the logical level command at the replication site; and
deleting the logical level command from the undo log.
7. The method of claim 5 further comprising:
if an inverse command does not exist for at least one logical level command:
selecting a snapshot taken at a point in time before a desired time;
reverting the selected snapshot; and
applying logical level commands from a redo log of the journal up to the desired time.
8. The method of claim 7 further comprising:
deleting old commands from the redo log as commands are written to the redo log when the redo log is full; and
deleting snapshots relating to points in time for which commands were deleted from the redo log.
9. The method of claim 1 further comprising initializing the replication site, comprising:
taking a snapshot at the production site;
copying the snapshot of the production site to the replication site; and
writing the replica of the logical level command to the journal at the replication site.
10. The method of claim 1 wherein transmitting the replica of the logical level command to the replication site comprises:
sending the replica of the logical level command from the splitter at the production site to a data protection appliance at the production site; and
forwarding the intercepted logical level command from the data protection appliance at the production site to a data protection appliance at the replication site for applying at the replication site.
11. A system comprising:
a replication site;
a production site comprising a logical level splitter configured to intercept a logical level command, create a replica of the logical level command, and transmit the replica of the logical level command toward the replication site;
a data protection appliance at the replication site configured to receive the replica of the logical level command, write the replica of the logical level command to a journal at the replication site, and advance a data storage state of the replication site forward to a particular data storage state at a particular point in time by reading logical level commands from a redo log of the journal and determining whether an inverse command for each of the logical level commands exists.
12. The system of claim 11 wherein the intercepted logical level command is selected from a group consisting of file system operations, database operations and block operations.
13. The system of claim 11 further comprising a player at the replication site configured to, if an inverse command exists for each logical level command, for each logical level command, create an inverse operation of the logical level command, write the inverse operation of the logical level command to an undo log of the journal, apply the logical level command at the replication site, and delete the logical level command from the redo log.
14. A The system of claim 11 further comprising a player at the replication site configured to, if an inverse command does not exist for at least one logical level command, take a snapshot of the replication site, store the snapshot at the replication site, and apply the logical level commands at the replication site.
15. The system of claim 11 further comprising the data protection appliance configured to restore a data storage state of the replication site backward to a particular data storage state at a particular point in time by reading logical level commands from an undo log of the journal up to a desired time and determining whether an inverse command for each of the logical level commands exists.
16. The system of claim 15 further comprising a player at the replication site configured to, if an inverse command exists for each logical level command, then for each logical level command create an inverse operation of each logical level command, write the inverse operation of the logical level command to a redo log of the journal, apply the logical level command at the replication site, and delete the logical level command from the undo log.
17. The method of claim 15 further comprising a player at the replication site configured to, if an inverse command does not exist for at least one logical level command, select a snapshot taken at a point in time before the desired time, revert the selected snapshot, and apply logical level commands from a redo log of the journal up to the desired time.
18. The method of claim 17 wherein the data protection appliance is further configured to delete old commands from the redo log as commands are written to the redo log when the redo log is full and delete snapshots relating to points in time for which commands were deleted from the redo log.
19. The system of claim 11 further comprising a data protection appliance at the production site configured to initialize the replication site by taking a snapshot at the production site, copying the snapshot of the production site to the replication site, and writing the replica of the logical level command to the journal at the replication site.
20. The system of claim 11 wherein the logical level splitter is further configured to send the replica of the logical level command to a data protection appliance at the production site and forward the intercepted logical level command from the data protection appliance at the production site to the data protection appliance at the replication site for applying at the replication site.
21. A computer program product having a non-transitory computer readable storage medium with instructions encoded thereon that, when executed by a processor of a computer, causes the computer to:
intercept a logical level command at a splitter at a production site;
create a replica of the logical level command at the production site;
transmit the replica of the logical level command toward a replication site;
receive the replica of the logical level command at the replication site;
write the replica of the logical level command to a journal at the replication site; and
advance a data storage state of the replication site forward to a particular data storage state at a particular point in time by reading logical level commands from a redo log of the journal and determining whether an inverse command for each of the logical level commands exists.