1PMEMPOOL_SYNC(3) PMDK Programmer's Manual PMEMPOOL_SYNC(3)
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6 pmempool_sync(), pmempool_transform() -- pool set synchronization and
7 transformation
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10 #include <libpmempool.h>
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12 int pmempool_sync(const char *poolset_file,
13 unsigned flags); (EXPERIMENTAL)
14 int pmempool_transform(const char *poolset_file_src,
15 const char *poolset_file_dst, unsigned flags); (EXPERIMENTAL)
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18 The pmempool_sync() function synchronizes data between replicas within
19 a pool set.
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21 pmempool_sync() accepts two arguments:
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23 · poolset_file - a path to a pool set file,
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25 · flags - a combination of flags (ORed) which modify how synchroniza‐
26 tion is performed.
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28 NOTE: Only the pool set file used to create the pool should be used
29 for syncing the pool.
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31 The following flags are available:
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33 · PMEMPOOL_DRY_RUN - do not apply changes, only check for viability of
34 synchronization.
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36 pmempool_sync() checks that the metadata of all replicas in a pool set
37 is consistent, i.e. all parts are healthy, and if any of them is not,
38 the corrupted or missing parts are recreated and filled with data from
39 one of the healthy replicas.
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41 If a pool set has the option SINGLEHDR (see poolset(5)), the internal
42 metadata of each replica is limited to the beginning of the first part
43 in the replica. If the option NOHDRS is used, replicas contain no in‐
44 ternal metadata. In both cases, only the missing parts or the ones
45 which cannot be opened are recreated with the pmempool_sync() function.
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47 pmempool_transform() modifies the internal structure of a pool set. It
48 supports the following operations:
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50 · adding one or more replicas,
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52 · removing one or more replicas_WINUX(.,,
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54 · adding or removing pool set options.)
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56 Only one of the above operations can be performed at a time.
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58 pmempool_transform() accepts three arguments:
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60 · poolset_file_src - pathname of the pool set file for the source pool
61 set to be changed,
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63 · poolset_file_dst - pathname of the pool set file that defines the new
64 structure of the pool set,
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66 · flags - a combination of flags (ORed) which modify how synchroniza‐
67 tion is performed.
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69 The following flags are available:
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71 · PMEMPOOL_DRY_RUN - do not apply changes, only check for viability of
72 transformation.
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74 When adding or deleting replicas, the two pool set files can differ on‐
75 ly in the definitions of replicas which are to be added or deleted.
76 When adding or removing pool set options (see poolset(5)), the rest of
77 both pool set files have to be of the same structure. The operation of
78 adding/removing a pool set option can be performed on a pool set with
79 local replicas only. To add/remove a pool set option to/from a pool
80 set with remote replicas, one has to remove the remote replicas first,
81 then add/remove the option, and finally recreate the remote replicas
82 having added/removed the pool set option to/from the remote replicas'
83 poolset files. To add a replica it is necessary for its effective size
84 to match or exceed the pool size. Otherwise the whole operation fails
85 and no changes are applied. If none of the pool set options is used,
86 the effective size of a replica is the sum of sizes of all its part
87 files decreased by 4096 bytes per each part file. The 4096 bytes of
88 each part file is utilized for storing internal metadata of the pool
89 part files. If the option SINGLEHDR is used, the effective size of a
90 replica is the sum of sizes of all its part files decreased once by
91 4096 bytes. In this case only the first part contains internal metada‐
92 ta. If the option NOHDRS is used, the effective size of a replica is
93 the sum of sizes of all its part files. In this case none of the parts
94 contains internal metadata.
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97 pmempool_sync() and pmempool_transform() return 0 on success. Other‐
98 wise, they return -1 and set errno appropriately.
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101 The pmempool_sync() API is experimental and it may change in future
102 versions of the library.
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104 The pmempool_transform() API is experimental and it may change in fu‐
105 ture versions of the library.
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108 libpmemlog(7), libpmemobj(7) and <http://pmem.io>
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112PMDK - pmempool API version 1.3 2018-03-13 PMEMPOOL_SYNC(3)