Provided by: libpmempool-dev_1.4.1-0ubuntu1~18.04.1_amd64 
NAME
pmempool_sync(), pmempool_transform() - pool set synchronization and transformation
SYNOPSIS
#include <libpmempool.h>
int pmempool_sync(const char *poolset_file,
unsigned flags); (EXPERIMENTAL)
int pmempool_transform(const char *poolset_file_src,
const char *poolset_file_dst, unsigned flags); (EXPERIMENTAL)
DESCRIPTION
The pmempool_sync() function synchronizes data between replicas within a pool set.
pmempool_sync() accepts two arguments:
• poolset_file - a path to a pool set file,
• flags - a combination of flags (ORed) which modify how synchronization is performed.
NOTE: Only the pool set file used to create the pool should be used for syncing the pool.
The following flags are available:
• PMEMPOOL_DRY_RUN - do not apply changes, only check for viability of synchronization.
pmempool_sync() checks that the metadata of all replicas in a pool set is consistent, i.e. all parts are
healthy, and if any of them is not, the corrupted or missing parts are recreated and filled with data
from one of the healthy replicas.
If a pool set has the option SINGLEHDR (see poolset(5)), the internal metadata of each replica is limited
to the beginning of the first part in the replica. If the option NOHDRS is used, replicas contain no
internal metadata. In both cases, only the missing parts or the ones which cannot be opened are
recreated with the pmempool_sync() function.
pmempool_transform() modifies the internal structure of a pool set. It supports the following
operations:
• adding one or more replicas,
• removing one or more replicas_WINUX(.,,
• adding or removing pool set options.)
Only one of the above operations can be performed at a time.
pmempool_transform() accepts three arguments:
• poolset_file_src - pathname of the pool set file for the source pool set to be changed,
• poolset_file_dst - pathname of the pool set file that defines the new structure of the pool set,
• flags - a combination of flags (ORed) which modify how synchronization is performed.
The following flags are available:
• PMEMPOOL_DRY_RUN - do not apply changes, only check for viability of transformation.
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 pool set
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.
RETURN VALUE
pmempool_sync() and pmempool_transform() return 0 on success. Otherwise, they return -1 and set errno
appropriately.
NOTES
The pmempool_sync() API is experimental and it may change in future versions of the library.
The pmempool_transform() API is experimental and it may change in future versions of the library.
SEE ALSO
libpmemlog(7), libpmemobj(7) and <http://pmem.io>