1PMEMPOOL-TRANSFORM(1)      PMDK Programmer's Manual      PMEMPOOL-TRANSFORM(1)
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NAME

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

9              pmempool transform [options] <poolset_file_src> <poolset_file_dst>
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DESCRIPTION

12       The  pmempool  transform  command modifies internal structure of a pool
13       set defined by the poolset_file_src file, according to a structure  de‐
14       scribed in the poolset_file_dst file.
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16       The following operations are supported:
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18       • adding  replicas - one or more new replicas can be added and synchro‐
19         nized with other replicas in the pool set,
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21       • removing replicas - one or more replicas can be removed from the pool
22         set ,
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24       • adding or removing pool set options.
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26       Only one of the above operations can be performed at a time.
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28       Currently  adding  and  removing  replicas are allowed only for pmemobj
29       pools (see libpmemobj(7)).
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31       The poolset_file_src argument  provides  the  source  pool  set  to  be
32       changed.
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34       The poolset_file_dst argument points to the target pool set.
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36       When adding or deleting replicas, the two pool set files can differ on‐
37       ly in the definitions of replicas which are to  be  added  or  deleted.
38       When  adding or removing pool set options (see poolset(5)), the rest of
39       both pool set files have to be of the same structure.  The operation of
40       adding/removing  a  pool set option can be performed on a pool set with
41       local replicas only.  To add/remove a pool set option  to/from  a  pool
42       set  with remote replicas, one has to remove the remote replicas first,
43       then add/remove the option, and finally recreate  the  remote  replicas
44       having  added/removed  the pool set option to/from the remote replicas’
45       poolset files.  To add a replica it is necessary for its effective size
46       to  match or exceed the pool size.  Otherwise the whole operation fails
47       and no changes are applied.  If none of the poolset  options  is  used,
48       the  effective  size  of  a replica is the sum of sizes of all its part
49       files decreased by 4096 bytes per each part file.  The  4096  bytes  of
50       each  part  file  is utilized for storing internal metadata of the pool
51       part files.  If the option SINGLEHDR is used, the effective size  of  a
52       replica  is  the  sum  of sizes of all its part files decreased once by
53       4096 bytes.  In this case only the first part contains internal metada‐
54       ta.   If  the option NOHDRS is used, the effective size of a replica is
55       the sum of sizes of all its part files.  In this case none of the parts
56       contains internal metadata.
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58   Available options:
59       -d, --dry-run
60              Enable  dry run mode.  In this mode no changes are applied, only
61              check for viability of the operation is performed.
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63       -v, --verbose
64              Increase verbosity level.
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66       -h, --help
67              Display help message and exit.
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EXAMPLES

70   Example 1.
71       Let files /path/poolset_file_src and  /path/poolset_file_dst  have  the
72       following contents:
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74              PMEMPOOLSET
75              20M /0/partfile1
76              20M /0/partfile2
77              25M /0/partfile3
78              REPLICA
79              40M /1/partfile1
80              20M /1/partfile2
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82              PMEMPOOLSET
83              20M /0/partfile1
84              20M /0/partfile2
85              25M /0/partfile3
86              REPLICA
87              40M /1/partfile1
88              20M /1/partfile2
89              REPLICA
90              50M /2/partfile1
91              20M /2/partfile2
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93       Then, the command
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95       pmempool transform /path/poolset_file_src /path/poolset_file_dst
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97       adds  a  replica  to the pool set.  All other replicas remain unchanged
98       and the size of the pool remains 60M.
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100   Example 2.
101       Let files /path/poolset_file_src and  /path/poolset_file_dst  have  the
102       following contents:
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104              PMEMPOOLSET
105              20M /0/partfile1
106              20M /0/partfile2
107              25M /0/partfile3
108              REPLICA
109              40M /1/partfile1
110              20M /1/partfile2
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112              PMEMPOOLSET
113              20M /0/partfile1
114              20M /0/partfile2
115              25M /0/partfile3
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117       Then
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119       pmempool_transform /path/poolset_file_src /path/poolset_file_dst
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121       deletes  the  second  replica from the pool set.  The first replica re‐
122       mains unchanged and the size of the pool is still 60M.
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SEE ALSO

125       pmempool(1),   libpmemblk(7),   libpmemlog(7),    libpmempool(7)    and
126       <https://pmem.io>
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130PMDK - pmem Tools version 1.4     2021-07-22             PMEMPOOL-TRANSFORM(1)
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