on

    uname -a
        Linux lab010.DOMAIN.net 3.18.0-2.g99a9f76-xen #1 SMP Sun Dec 14
10:25:49 UTC 2014 (99a9f76) x86_64 x86_64 x86_64 GNU/Linux
    lsb_release -rd
        Description:    openSUSE 13.2 (Harlequin) (x86_64)
        Release:        13.2
    mdadm --version
        mdadm - v3.3.1 - 5th June 2014

i am getting these email notices from system cron every couple of days

    ...
    From: "(Cron Daemon)" <cron-admin=lab010.DOMAIN.net@DOMAIN.net>
    To: cron-admin=lab010.DOMAIN.net@DOMAIN.net
    Subject: Cron <root@server> source /etc/sysconfig/mdadm; [ -n
"$MDADM_CHECK_DURATION" -a -x /usr/share/mdadm/mdcheck ] &&
/usr/share/mdadm/mdcheck --continue --duration "$MDADM_CHECK_DURATION"
    Content-Type: text/plain; charset=UTF-8
    Auto-Submitted: auto-generated
    Precedence: bulk
    X-Cron-Env: <XDG_SESSION_ID=569>
    X-Cron-Env: <XDG_RUNTIME_DIR=/run/user/0>
    X-Cron-Env: <LANG=POSIX>
    X-Cron-Env: <LC_CTYPE=en_US.UTF-8>
    X-Cron-Env: <PATH=/sbin:/usr/sbin:/bin:/usr/bin>
    X-Cron-Env: <SHELL=/bin/sh>
    X-Cron-Env: <HOME=/root>
    X-Cron-Env: <LOGNAME=root>
    X-Cron-Env: <USER=root>
    ...
    /var/lib/mdcheck/.md-check-8965: line 5: none: No such file or directory
    /var/lib/mdcheck/.md-check-8965: line 5: none: No such file or directory
    /usr/share/mdadm/mdcheck: line 109: echo: write error: Invalid argument

they originate from

    grep -rlni mdcheck /etc/cron*
        /etc/cron.d/mdadm
    cat /etc/cron.d/mdadm
        #
        # cron.d/mdadm - regular redundancy checks
        #

        # Start checking each month early in the morning.
        # Continue each day until all done

        PATH=/sbin:/usr/sbin:/bin:/usr/bin
        0 1 * * 0 root source /etc/sysconfig/mdadm; [ -n
"$MDADM_CHECK_DURATION" -a -x /usr/share/mdadm/mdcheck -a $(date +\%d) -le 7 ]
&& /usr/share/mdadm/mdcheck --duration "$MDADM_CHECK_DURATION"
        0 1 * * 1-6 root source /etc/sysconfig/mdadm; [ -n
"$MDADM_CHECK_DURATION" -a -x /usr/share/mdadm/mdcheck ] &&
/usr/share/mdadm/mdcheck --continue --duration "$MDADM_CHECK_DURATION"

checking

cat /usr/share/mdadm/mdcheck
    ...
    # To support '--continue', arrays are identified by UUID and the
'sync_completed'
    # value is stored  in /var/lib/mdcheck/$UUID
    ...
    sysname() {
        set `ls -lLd $1`
        maj=${5%,}
        min=$6
        readlink -f /sys/dev/block/$maj:$min
    }
    ..
    for dev in /dev/md?*
    do
        [ -e "$dev" ] || continue
        sys=`sysname $dev`
    ...
        echo $start > $fl
109        echo $start > $sys/md/sync_min
        echo check > $sys/md/sync_action
    ...

on my system

    ls -al /var/lib/mdcheck/
        total 16K
        drwxr-xr-x  2 root root 4.0K Dec 17 01:56 ./
        drwxr-xr-x 78 root root 4.0K Dec 15 13:59 ../
        -rw-r--r--  1 root root  319 Dec 13 01:00 .md-check-13566
        -rw-r--r--  1 root root  319 Dec 15 01:00 .md-check-17179

and

    cat /proc/mdstat | grep md
        md0 : active raid1 sdb1[1] sda1[0]
        md1 : active raid1 sda2[0] sdb2[2]
        md2 : active raid10 sdd1[1] sde1[4] sdc1[0] sdf1[3]

    ls -al /sys/dev/block/ | egrep "md0|md1|md2"
        lrwxrwxrwx 1 root root 0 Dec 17 05:56 9:0 ->
../../devices/virtual/block/md0/
        lrwxrwxrwx 1 root root 0 Dec 17 05:56 9:1 ->
../../devices/virtual/block/md1/
        lrwxrwxrwx 1 root root 0 Dec 17 05:56 9:2 ->
../../devices/virtual/block/md2/

    ls -al /sys/dev/block/9:{0,1,2}/md/sync_min
        -rw-r--r-- 1 root root 4.0K Dec 17 06:00 /sys/dev/block/9:0/md/sync_min
        -rw-r--r-- 1 root root 4.0K Dec 17 06:00 /sys/dev/block/9:1/md/sync_min
        -rw-r--r-- 1 root root 4.0K Dec 17 01:00 /sys/dev/block/9:2/md/sync_min

    cat /etc/sysconfig/mdadm 
        MDADM_DELAY=60
        MDADM_MAIL="gk@DOMAIN.com"
        MDADM_PROGRAM=""
        MDADM_RAIDDEVICES="/dev/md0 /dev/md1 /dev/md2"
        MDADM_SCAN=yes
        MDADM_CONFIG="/etc/mdadm.conf"
        MDADM_SEND_MAIL_ON_START=yes
        BOOT_MD_USE_MDADM_CONFIG=yes
        MDADM_DEVICE_TIMEOUT="60"
        MDADM_CHECK_DURATION="12 hours"