Replication of a consistency group of data storage objects from servers in a data network
Consistency errors may arise during replication of diverse data storage objects from servers in a data network. For preventing consistency errors, a server is programmed for responding to a request for a report of whether or not the server can replicate the dataset without causing a consistency error. Such a report is useful for replicating a consistency group of objects from more than one server. Preparation for replication can be begun at each of the servers, and if any of the servers fail to report that replication can be done without causing a consistency error, the preparation can be aborted so that write access by applications will not be disrupted while the potential problem is diagnosed and eliminated.
1. In a data processing network including a first server, a computer-implemented method comprising the steps of:
receiving a request to determine whether or not the first server can replicate a first dataset from computer data storage of the first server without causing a consistency error, and
responding to the request by determining whether or not the first server can replicate the first dataset from the computer data storage of the first server without causing a consistency error, and reporting whether or not the first server can replicate the first dataset from the computer data storage of the first server without causing a consistency error;
wherein the first server determines whether or not the first server can replicate the first dataset from the computer data storage of the first server without causing a consistency error by suspending write access of applications to the first dataset, and then checking whether any applications fail to release any read-write locks upon the first dataset;
wherein the data processing network includes a plurality of second servers providing access of applications to respective second datasets, and wherein a controller sends, to each of the second servers, a request to determine whether or not each of the second servers can replicate the respective second dataset without causing a consistency error, and wherein each of the second servers returns, to the controller, a report of whether or not said each of the second servers can replicate the respective second dataset without causing a consistency error; and
which includes the controller receiving the reports from the second servers, and upon checking that all of the second servers can replicate their respective second datasets without causing consistency errors, the controller sending a replicate request to each of the second servers in order to replicate a consistency group of the second datasets from the second servers.
2. The computer-implemented method as claimed in claim 1 , wherein the data processing network includes a client operated by a system administrator, and the client originates the request to determine whether or not the first server can replicate the first dataset from the computer data storage of the first server without causing a consistency error, and the client receives the report of whether or not the first server can replicate the first dataset from the computer data storage of the first server without causing a consistency error.
3. The computer-implemented method as claimed in claim 1 , wherein the first server reports that the first dataset cannot be replicated from the computer data storage of the first server without a consistency error, and wherein the method further includes a system administrator responding to the report by shutting down an application having access to the first dataset.
4. The computer-implemented method as claimed in claim 1 , which further includes the first server receiving a destination validation request to determine whether or not the first server can connect to a destination for replicated data from the first dataset; and
the first server responding to the destination validation request by determining whether or not the first server can connect to the destination for the replicated data from the first dataset, and reporting whether or not the first server can connect to the destination for the replicated data from the first dataset.
5. The computer-implemented method as claimed in claim 1 , which further includes the first server receiving a destination configuration request to configure a destination for replicated data from the first dataset; and
the first server responding to the destination configuration request by attempting to configure the destination for storage of replicated data from the first dataset, and reporting whether or not the destination for the replicated data from the first dataset has been successfully configured for storage of the replicated data from the first dataset.
6. The computer-implemented method as claimed in claim 1 , wherein clients in the data processing network use different high-level storage access protocols to access the respective second datasets.
7. The computer-implemented method as claimed in claim 1 , wherein at least one application holds a read-write lock upon the first dataset when the first server suspends write access of applications to the first dataset, and the first server requests said at least one application to release the read-write lock upon the first dataset.
8. The computer-implemented method as claimed in claim 1 , which includes replicating the first dataset by activating a snapshot facility in the first server to take a snapshot copy of the first dataset in the computer data storage of the first server, and activating a replication control protocol facility in the first server to replicate the first dataset over the data processing network from the first server using the Transmission Control Protocol.
9. The computer-implemented method as claimed in claim 1 , wherein the method includes replicating a first snapshot copy of the first dataset over the data processing network from the first server and then replicating, over the data processing network from the first server, changes made to the first dataset from the time of the first snapshot copy of the first dataset up to a time of making a second snapshot copy of the first dataset.
10. The computer-implemented method as claimed in claim 1 , wherein the first dataset includes a logical unit number (LUN) of storage, and the method includes encapsulating the logical unit number (LUN) of storage in a file and replicating the file over the data processing network from the first server.
11. In a data processing network including a server, a computer-implemented method comprising the steps of:
receiving a request to determine whether or not the server can replicate a dataset from computer data storage of the server without causing a consistency error, and
responding to the request by determining whether or not the server can replicate the dataset from the computer data storage of the server without causing a consistency error, and reporting whether or not the server can replicate the dataset from the computer data storage of the server without causing a consistency error;
wherein the data processing network includes a plurality of servers providing access of applications to respective datasets, and wherein a controller sends, to each of the servers, a request to determine whether or not each of the servers can replicate the respective dataset without causing a consistency error, and wherein each of the servers returns, to the controller, a report of whether or not said each of the servers can replicate the respective dataset without causing a consistency error; and
which includes the controller receiving the reports from the servers, and upon checking that all of the servers can replicate their respective datasets without causing consistency errors, the controller sending a replicate request to each of the servers in order to replicate a consistency group of the datasets from the servers.