From mboxrd@z Thu Jan  1 00:00:00 1970
From: Ram Ramesh <rramesh2400@gmail.com>
Subject: mdadm --grow with --backup-file does not create backupfile?
Date: Sun, 12 Oct 2014 20:26:05 -0500
Message-ID: <543B2A2D.9080407@gmail.com>
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I added a new disk and grew my raid6 md0 with the following command line

    sudo mdadm --grow --raid-devices=5
    --backup-file=/root/grow_md0.bkp_file --layout=normalise /dev/md0

I got a response that stated that mdadm needed to backup 384K of data. 
However, when I checked after about 5min there was no backup file. Is 
this expected?

    386 > sudo ls /root
    <no files. so no output>
    387 > sudo ls /root/grow_md0.bkp_file
    ls: cannot access /root/grow_md0.bkp_file: No such file or directory

Ramesh