NAME

       pmempool-transform - Modify internal structure of a pool set.

SYNOPSIS

              pmempool transform [options] <poolset_file_src> <poolset_file_dst>

DESCRIPTION

       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:

       • adding replicas - one or more new replicas can be  added  and  synchronized  with  other
         replicas in the pool set,

       • removing replicas - one or more replicas can be removed from the pool set ,

       • adding or removing pool set options.

       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.

   Available options:
       -d, --dry-run
              Enable dry run mode.  In this mode no changes are applied, only check for viability
              of the operation is performed.

       -v, --verbose
              Increase verbosity level.

       -h, --help
              Display help message and exit.

EXAMPLES

   Example 1.
       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.

   Example 2.
       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.

SEE ALSO

       pmempool(1), libpmemblk(7), libpmemlog(7), libpmempool(7) and <https://pmem.io>