| PMEMPOOL-TRANSFORM(1) | PMDK Programmer's Manual | PMEMPOOL-TRANSFORM(1) |
pmempool-transform - Modify internal structure of a pool set.
pmempool transform [options] <poolset_file_src> <poolset_file_dst>
The pmempool transform command modifies internal structure of a pool set defined by the poolset_file_src file, according to a structure described in the poolset_file_dst file.
The following operations are supported:
Only one of the above operations can be performed at a time.
Currently adding and removing replicas are allowed only for pmemobj pools (see libpmemobj(7)).
The poolset_file_src argument provides the source pool set to be changed.
The poolset_file_dst argument points to the target pool set.
When adding or deleting replicas, the two pool set files can differ only in the definitions of replicas which are to be added or deleted. When adding or removing pool set options (see poolset(5)), the rest of both pool set files have to be of the same structure. The operation of adding/removing a pool set option can be performed on a pool set with local replicas only. To add/remove a pool set option to/from a pool set with remote replicas, one has to remove the remote replicas first, then add/remove the option, and finally recreate the remote replicas having added/removed the pool set option to/from the remote replicas' poolset files. To add a replica it is necessary for its effective size to match or exceed the pool size. Otherwise the whole operation fails and no changes are applied. If none of the poolset options is used, the effective size of a replica is the sum of sizes of all its part files decreased by 4096 bytes per each part file. The 4096 bytes of each part file is utilized for storing internal metadata of the pool part files. If the option SINGLEHDR is used, the effective size of a replica is the sum of sizes of all its part files decreased once by 4096 bytes. In this case only the first part contains internal metadata. If the option NOHDRS is used, the effective size of a replica is the sum of sizes of all its part files. In this case none of the parts contains internal metadata.
Let files /path/poolset_file_src and /path/poolset_file_dst have the following contents:
PMEMPOOLSET 20M /0/partfile1 20M /0/partfile2 25M /0/partfile3 REPLICA 40M /1/partfile1 20M /1/partfile2
PMEMPOOLSET 20M /0/partfile1 20M /0/partfile2 25M /0/partfile3 REPLICA 40M /1/partfile1 20M /1/partfile2 REPLICA 50M /2/partfile1 20M /2/partfile2
Then, the command
pmempool transform /path/poolset_file_src /path/poolset_file_dst
adds a replica to the pool set. All other replicas remain unchanged and the size of the pool remains 60M.
Let files /path/poolset_file_src and /path/poolset_file_dst have the following contents:
PMEMPOOLSET 20M /0/partfile1 20M /0/partfile2 25M /0/partfile3 REPLICA 40M /1/partfile1 20M /1/partfile2
PMEMPOOLSET 20M /0/partfile1 20M /0/partfile2 25M /0/partfile3
Then
pmempool_transform /path/poolset_file_src /path/poolset_file_dst
deletes the second replica from the pool set. The first replica remains unchanged and the size of the pool is still 60M.
pmempool(1), libpmemblk(7), libpmemlog(7), libpmempool(7) and <https://pmem.io>
| 2022-08-25 | PMDK - pmem Tools version 1.4 |