Item12477: bit of doc for the PFS

PlainFileStoreContrib/data/System/PlainFileStoreContrib.txt

@@ -1,4 +1,4 @@
-%META:TOPICINFO{author="ProjectContributor" date="1399553949" version="1"}%
+%META:TOPICINFO{author="ProjectContributor" date="1418920586" version="1"}%
 ---+!! PlainFileStoreContrib
 <!--
    * Set SHORTDESCRIPTION = %$SHORTDESCRIPTION%
@@ -32,6 +32,9 @@ everything is stored at least twice; same as in the RCS stores)
 Developers note: this contrib is tested using the standard store unit tests.
 
 ---++ Moving between store implementations
+
+---+++ Foswiki < 1.2
+
 The =tools/change_store = script included in this module allows you to move
 between different store implementations. The script uses internal, unpublished
 store APIs.
@@ -46,6 +49,14 @@ Run the script without parameters to get instructions:
 $ tools/change_store.pl -I lib
 </verbatim>
 
+%X% *it is dangerous* to run two different store implementations over the
+same data, so once you have completed the transfer you should *remove* all ,v files from the store. *All* of them.
+
+---+++ Foswiki 1.2 and later
+
+The =tools/bulk_copy.pl= script should be used to move topics between two
+Foswiki instances running different store implementations. *Do not* share data areas between store implementations.
+
 ---++ Developer Notes
 Testing is performed using the standard system tests. Because some
 of these tests are written assuming a broken store (the RCS based stores