Merge lp://staging/~sergei.glushchenko/percona-xtrabackup/2.1-xb-bug1222062 into lp://staging/percona-xtrabackup/2.1

Sergei,

- I would call the option just ‘--close-files’, because ‘handlers’ looks
  confusing (and should be ‘handles’ for that matter).
- users are generally not supposed to call xtrabackup directly, but use
  innobackupex instead. Why is there no corresponding innobackupex
  option?
- please add the warning to the built-in help for xtrabackup option
- please also update the docs (with the “use at your own risk” warning )
- the ‘-i’ option to run.sh has been added to usage text, but is not
  actually handled
- XB_EXTRA_ARGS in run.sh is unused
- srv_close_file_handlers should be initialized to FALSE for consistency

In the warning text, I would also explain the consequences briefly, rather than refer users to a bug with a long discussion.

Hi Alexey,

All comments are reasonable. I just want to explain why I haven't implement option for innobackupex. We don't recommend to use this option and normally user will not use it. However, if he need it badly, then he actually nows what he is doing. So there is an option for him to add it into my.cnf. Isn't it enough?

Sure, but what if a user hits the open files limit, but still wants to create full backups with mysql.* and other MyISAM tables, buffer pool dumps, etc.?

He can put the option into [xtrabackup] of my.cnf, it will work file. Anyways I already added the corresponding innobackupex option.

I'd be very cautious to put such an option to my.cnf. It's too easy to forget and replicate it to another server, for example. Anyway, now the users are free to choose how they want to use it. Thanks.