2012/9/17 NeilBrown <neilb@xxxxxxx>:
> On Mon, 17 Sep 2012 10:30:49 +0800 Jack Wang <jack.wang.usish@xxxxxxxxx>
> wrote:
>
>> I check into code in mdmonitor.c in function check_array:
>>
>> fd = open(dev, O_RDONLY);
>> if (fd < 0) {
>> if (!st->err)
>> alert("DeviceDisappeared", dev, NULL, ainfo);
>> st->err=1;
>> return 0;
>> }
>> fcntl(fd, F_SETFD, FD_CLOEXEC);
>> if (ioctl(fd, GET_ARRAY_INFO, &array)<0) {
>> if (!st->err)
>> alert("DeviceDisappeared", dev, NULL, ainfo);
>> st->err=1;
>> close(fd);
>> return 0;
>> }
>> /* It's much easier to list what array levels can't
>> * have a device disappear than all of them that can
>> */
>> if (array.level == 0 || array.level == -1) {
>> if (!st->err)
>> alert("DeviceDisappeared", dev, "Wrong-Level", ainfo);
>> st->err = 1;
>> close(fd);
>> return 0;
>> }
>>
>> I suspect above code lead to the DeviceDisapeared event you see, not
>> sure why this get GET_ARRAY_INFO return array.level == 0 means Device
>> Disappeared?
>>
>> Anyone who more familiar with the logic may gave a comment?
>
>
> It isn't possible or meaningful to monitor RAID0 devices - there is nothing
> to see, nothing that can happen, nothing to report.
>
> mdadm will normally completely ignore RAID0 devices.
>
> If you run
> mdadm --monitor /dev/md1
>
> when md1 is a RAID0 device, then it will be required to actively forget about
> it, so it reports that the device has disappeared (because it was on the
> list, but now isn't).
>
> This shouldn't happen if you run "mdadm --monitor --scan" which is the
> standard usage. It that what is happening?
>
> NeilBrown
>
Thanks Neil for always kindly help.
The device disappeared event report when restart mdmonitor service,
which will mdadm with options PIDFILE=/var/run/mdadm/mdadm.pid
PATH=/sbin:/usr/sbin:$PATH
RETVAL=0
OPTIONS="-F -y -f -s -i $PIDFILE"
And I checked man page of mdadm which clear claimed :
DeviceDisappeared
An md array which previously was configured appears to no
longer be configured. (syslog priority: Critical)
If mdadm was told to monitor an array which is RAID0 or Lin-
ear, then it will report DeviceDisappeared with the extra
information Wrong-Level. This is because RAID0 and Linear
do not support the device-failed, hot-spare and resync oper-
ations which are monitored.
Thanks again for your time.
Jack
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