Migration issue : archive_xlog directory not renamed

[Krysztophe]

Archives were previously stored by default in $BACKUP_DIR/archive_xlog, now in $BACKUP_DIR/archive_wal. So, if $ARCHIVE_DIR was not explicitly set, pitrery will put the archives in a different directory than before. Archiving still succeeds, but a check returns an error, purge will not find old archives, and I suppose that a restore woud fail. That could lead to as big problem for an user that did not realize that pitrery was upgraded.

Suggestions:

• improve doc and add a migration checklist that suggest setting $ARCHIVE_DIR explicitly or renaming archive_xlog, running check ...
• Automatically create a symlink if ARCHIVE_DIR is not set and that the old default directory is present ? I would not automatically rename the existing archive_xlog.
• check: in case of a failure, try to detect the old default archive_xlog, and give a hint
• restore : if the old archive_xlog is detected, raise a warning and suggest a check