On Fri, 23 Oct 2015 at 06:37 Neil Brown [off-list ref] wrote:

Liwei [off-list ref] writes:

quoted

Hi list,
    I tried growing a RAID6 array by executing the mdadm --add and
mdadm --grow --raid-devices commands. Usually that should run fine and
I can continue with pvresize.

That is incorrect.  You cannot run "pvresize" until the reshape
completes.

Ah, my bad. It's been a while since I did that. So if I had been
patient, all would have been well?

quoted

    This time however, the actual usable raid array size did not
change even though reshape begins. In my confusion, I decided to
reboot. That didn't solve the problem (and apparently the reshape was
interrupted, but mdadm shows the grown array as clean?)

Clean is expected.  It will be in an intermediate state, part has
reshaped to extra devices, part is still the original.

quoted

    I then executed mdadm --grow --size=max, which seemed to have
increased the array size, but apparently by too much. Now I'm getting
"attempt to access beyond end of device" errors for each of the
component drives. A new reshape operation has also begun, which I
expect would fail as the array size is now too big.

"--size" isn't the same as "--array-size".
"--size" is the size of the component devices to use.

The "attempt to access beyond end of device" errors are unexpected but
presumably related o the "--size=max".  Maybe the 'max' chosen was too
large.  That suggests a bug somewhere.
You probably want to reduce that size back to where it was.

I just realised I got the wrong command. I used --array-size=max
instead. A reboot seemed to have reverted the change.

quoted

    What did I do wrong and how can I remedy this?

Could we start with "mdadm --examine" status of all devices, "mdadm
--detail" of the array, and all kernel messages that could possibly
relate to the array since you first started this exercise?

Eventually it was a foul up on my part. Things seem to be back to
normal after a reboot, and the reshape is in progress. Apologies for
the confusion!

Liwei

NeilBrown

quoted

Liwei
--
To unsubscribe from this list: send the line "unsubscribe linux-raid" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html