RESYNCHRONIZATION OF OBJECTS IN A VIRTUAL STORAGE SYSTEM
An example method of resynchronizing a first replica of an object and a second replica of an object in an object storage system, includes: determining, by storage software in response to the second replica transitioning from failed to available, a stale sequence number for the second replica, the storage software having associated the stale sequence number with the second replica when the second replica failed; querying, by the storage software, block-level metadata for the object using the stale sequence number, the block-level metadata relating logical blocks of the object with sequence numbers for operations on the object; determining, by the software as a result of the querying, a set of the logical blocks each related to a sequence number being the same or after the stale sequence number; and copying, by the storage software, data of the set of logical blocks from the first replica to the second replica.
1 . A method of resynchronizing a first replica of an object and a second replica of an object in an object storage system, the object storge system providing storage for a host executing storage software, the method comprising:
determining, by the storage software in response to the second replica transitioning from failed to available, a stale sequence number for the second replica, the storage software having associated the stale sequence number with the second replica when the second replica failed;
querying, by the storage software, block-level metadata for the object using the stale sequence number, the block-level metadata relating logical blocks of the object with sequence numbers for operations on the object;
determining, by the software as a result of the querying, a set of the logical blocks each related to a sequence number being the same or after the stale sequence number; and
copying, by the storage software, data of the set of logical blocks from the first replica to the second replica.
2 . The method of claim 1 , further comprising:
activating, by the storage software, the second replica after the copying.
3 . The method of claim 1 , wherein the storage software determines extents representing the set of logical blocks from the querying, each of the extents indicating a starting logical block and an offset from the starting logical block, and wherein the storage software copies the data using the extents.
4 . The method of claim 1 , wherein the sequence numbers are unique and the storage software changes the sequence number for each of the operations.
5 . The method of claim 4 , wherein the stale sequence number is one of the sequence numbers.
6 . The method of claim 1 , wherein the host is part of a cluster of hosts, the hosts including local storage devices aggregated to form the object storage system.
7 . The method of claim 6 , wherein the block-level metadata further relates the logical blocks with physical blocks of the local storage devices.
8 . A non-transitory computer readable medium comprising instructions to be executed in a computing device to cause the computing device to carry out a method of resynchronizing a first replica of an object and a second replica of an object in an object storage system, the object storge system providing storage for a host executing storage software, the method comprising:
determining, by the storage software in response to the second replica transitioning from failed to available, a stale sequence number for the second replica, the storage software having associated the stale sequence number with the second replica when the second replica failed;
querying, by the storage software, block-level metadata for the object using the stale sequence number, the block-level metadata relating logical blocks of the object with sequence numbers for operations on the object;
determining, by the software as a result of the querying, a set of the logical blocks each related to a sequence number being the same or after the stale sequence number; and
copying, by the storage software, data of the set of logical blocks from the first replica to the second replica.
9 . The non-transitory computer readable medium of claim 8 , further comprising:
activating, by the storage software, the second replica after the copying.
10 . The non-transitory computer readable medium of claim 8 , wherein the storage software determines extents representing the set of logical blocks from the querying, each of the extents indicating a starting logical block and an offset from the starting logical block, and wherein the storage software copies the data using the extents.
11 . The non-transitory computer readable medium of claim 8 , wherein the sequence numbers are unique and the storage software changes the sequence number for each of the operations.
12 . The non-transitory computer readable medium of claim 11 , wherein the stale sequence number is one of the sequence numbers.
13 . The non-transitory computer readable medium of claim 8 , wherein the host is part of a cluster of hosts, the hosts including local storage devices aggregated to form the object storage system.
14 . The non-transitory computer readable medium of claim 13 , wherein the block-level metadata further relates the logical blocks with physical blocks of the local storage devices.
15 . A computer system, comprising:
a hardware platform comprising an interface to an object storage system, the object storage system storing an object having a first replica and a second replica;
system software, executing on the hardware platform, including storage software configured to:
determine, in response to the second replica transitioning from failed to available, a stale sequence number for the second replica, the storage software having associated the stale sequence number with the second replica when the second replica failed;
query block-level metadata for the object using the stale sequence number, the block-level metadata relating logical blocks of the object with sequence numbers for operations on the object;
determine, as a result of the querying, a set of the logical blocks each related to a sequence number being the same or after the stale sequence number; and
copy data of the set of logical blocks from the first replica to the second replica.
16 . The computer system of claim 15 , wherein the storage software is configured to:
activate the second replica after the copying.
17 . The computer system of claim 15 , wherein the storage software determines extents representing the set of logical blocks from the querying, each of the extents indicating a starting logical block and an offset from the starting logical block, and wherein the storage software copies the data using the extents.
18 . The computer system of claim 15 , wherein the sequence numbers are unique and the storage software changes the sequence number for each of the operations.
19 . The computer system of claim 18 , wherein the stale sequence number is one of the sequence numbers.
20 . The computer system of claim 15 , wherein the host is part of a cluster of hosts, the hosts including local storage devices aggregated to form the object storage system.