Accessing file system replica during ongoing replication operations
First Claim
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1. A method of accessing file system replicas, the method comprising:
- conducting replication operations on a file system hosted on a first data storage system repeatedly to update a replica of the file system on a second data storage system to reflect changes in the file system that occur in response to activities at the first data storage system over time;
in a course of conducting the replication operations, generating, by the second data storage system, a snap of the replica, the snap providing a point-in-time version of the replica of the file system; and
while the replication operations continue to update the replica, directing IO requests received by the second data storage system to the snap of the replica to effect read and/or write operations on the snap of the replica;
wherein conducting the replication operations includes performing discrete update operations on the replica to keep the replica current with changes made to the file system, wherein the first data storage system has a transaction log for storing pending metadata transactions for the file system, and wherein the method further comprises, prior to the second data storage system generating the snap;
the first data storage system applying the pending metadata transactions from the transaction log to the file system; and
after applying the pending metadata changes to the file system, the first data storage system sending a marker to the second data storage system, the marker identifying a point relative to the discrete update operations at which the pending metadata changes have been applied to the file system,wherein generating the snap by the second data storage system is performed only after the second data storage system has received the marker.
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Abstract
A technique for accessing replicas of file systems generates a snap (point-in-time version) of a replica on a destination site and provides access to the snap for reading and/or writing while replication operations on the replica between a source site and the destination site continue to be performed. As the snap is a separate object from the replica itself, users may access the snap without affecting the replica or disturbing ongoing replication activities. Users can also mount the snap to perform destination-driven backup operations, to test disaster recovery, and/or to perform other activities.
24 Citations
15 Claims
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1. A method of accessing file system replicas, the method comprising:
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conducting replication operations on a file system hosted on a first data storage system repeatedly to update a replica of the file system on a second data storage system to reflect changes in the file system that occur in response to activities at the first data storage system over time; in a course of conducting the replication operations, generating, by the second data storage system, a snap of the replica, the snap providing a point-in-time version of the replica of the file system; and while the replication operations continue to update the replica, directing IO requests received by the second data storage system to the snap of the replica to effect read and/or write operations on the snap of the replica; wherein conducting the replication operations includes performing discrete update operations on the replica to keep the replica current with changes made to the file system, wherein the first data storage system has a transaction log for storing pending metadata transactions for the file system, and wherein the method further comprises, prior to the second data storage system generating the snap; the first data storage system applying the pending metadata transactions from the transaction log to the file system; and after applying the pending metadata changes to the file system, the first data storage system sending a marker to the second data storage system, the marker identifying a point relative to the discrete update operations at which the pending metadata changes have been applied to the file system, wherein generating the snap by the second data storage system is performed only after the second data storage system has received the marker. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 15)
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11. A system comprising a first data storage system and a second data storage system coupled to the first data storage system, the first data storage system and the second data storage system each including a respective set of processors and memory, the system constructed and arranged to:
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conduct replication operations on a file system hosted on the first data storage system repeatedly to update a replica of the file system on the second data storage system to reflect changes in the file system that occur in response to activities at the first data storage system over time; in a course of conducting the replication operations, generate, by the second data storage system, a snap of the replica, the snap providing a point-in-time version of the replica of the file system; and while the replication operations continue to update the replica, direct 10 requests received by the second data storage system to the snap of the replica to effect read and/or write operations on the snap of the replica, wherein the first data storage system has a transaction log for storing pending metadata transactions for the file system, wherein, when constructed and arranged to conduct the replication operations, system is further constructed and arranged to perform discrete update operations on the replica to keep the replica current with changes made to the file system, and wherein the system is further constructed and arranged to, prior to the second data storage system generating the snap; apply, by the first data storage system, the pending metadata transactions from the transaction log to the file system; and after applying the pending metadata changes to the file system, send, by the first data storage system, a marker to the second data storage system, the marker identifying a point relative to the discrete update operations at which the pending metadata changes have been applied to the file system, wherein the system is constructed and arranged to generate the snap by the second data storage system only after the second data storage system has received the marker. - View Dependent Claims (12)
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13. A computer program product including a set of non-transitory, computer-readable media having instructions which, when executed by one or more processors, cause the processors to perform a method of accessing file system replicas, the method comprising:
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conducting replication operations on a file system hosted on a first data storage system repeatedly to update a replica of the file system on a second data storage system to reflect changes in the file system that occur in response to activities at the first data storage system over time; in a course of conducting the replication operations, generating, by the second data storage system, a snap of the replica, the snap providing a point-in-time version of the replica of the file system; and while the replication operations continue to update the replica, directing 10 requests received by the second data storage system to the snap of the replica to effect read and/or write operations on the snap of the replica, wherein the first data storage system has a transaction log for storing pending metadata transactions for the file system, wherein conducting the replication operations includes performing discrete update operations on the replica to keep the replica current with changes made to the file system, and wherein the method further comprises, prior to the second data storage system generating the snap; the first data storage system applying the pending metadata transactions from the transaction log to the file system; and after applying the pending metadata changes to the file system, the first data storage system sending a marker to the second data storage system, the marker identifying a point relative to the discrete update operations at which the pending metadata changes have been applied to the file system, wherein generating the snap by the second data storage system is performed only after the second data storage system has received the marker. - View Dependent Claims (14)
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Specification