Comment 7 for bug 1098566

In this case, following will be done:

a) Have a separate setting - sst-log-data-home-dir which will be ON by
default for this to work. (Optional: Detect the options from my.cnf and
set them accordingly). Setting is required because if older PXB is used
then SST shouldn't break. (so it can be turned off).

b) Will go only into xtrabackup-v2 only.

c) This will depend on --move-back --force functionality of PXB
(which will be added in 2.1.6).

d) Minimum required version of PXB will also be bumped to 2.1.6
and above.

e) Here is how it goes down:

    i) On joiner, SST will be streamed into a subdirectory of
    datadir - $datadir/.sst

    ii) Backup will be prepared there.

    iii) innobackupex --move-back --force ../ will be used to
    copy back.

    iv) Based on success, .sst directory will be removed.

f) The $datadir/.sst is required but not any other directory
because data directories usually are mounted on separate mount
points and, otherwise ENOSPC issue can arise.

g) This should also handle innodb-data-home-dir,
innodb-log-home-dir, innodb-log-arch-dir and other exotic
directory variables.