Re: [tlug] [Suspected Spam] RAID not seen by system

["Stephen J. Turnbull" <turnbull.stephen.fw@example.com>]

CL writes:

 > > 30 days doesn't sound reasonable for devices I'd consider plausible.
 > > "33000kbps" for the reshaping implies a little over 8 hours/TB, and in
 > > fact for RAID 5 I would expect only the new drive to be written (all
 > > have to be read, though), so a fraction of the time for full
 > > reshaping.
 > >
 > 
 > And yet, it wasn't considered all that unusual on other forums I checked at
 > the time.  Nor, are speeds of 40~60kbps for reshape considered all that odd
 > and slowing down to a stop during the process is not considered all that
 > unusual.

I believe you that there are reports, I just don't understand where
the slowdown could be.  There's no need for it that I can see.

 > $ sudo mdadm --stop /dev/md0
 > $ sudo mdadm --assemble --run --force --update=resync /dev/md0
 > $ cat /proc/mdstat

These all say what you've said in words.  This

 >         Raid Level : raid5
 >         Array Size : 14650670080 (13971.97 GiB 15002.29 GB)
 >      Used Dev Size : 2930134016 (2794.39 GiB 3000.46 GB)

is a little strange, though -- seems to indicate you're only using 1/5
of the array's space as the md device.

 > ? INFO: task mount:4104 blocked for more than 120 seconds.
 > ?       Tainted: P           OE     5.0.0-36-generic #39-Ubuntu
 > ? 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
 > ? INFO: task md0_reshape:4069 blocked for more than 120 seconds.
 > ?       Tainted: P           OE     5.0.0-36-generic #39-Ubuntu

Don't know what to say about that, except that reshape is waiting for
some resource it needs.  I guess mount and reshape could be deadlocked
but that doesn't seem all that likely.

 > The mdadm programmer / maintainer Neil Brown is an unstoppable fount of
 > knowledge.

At this point I can't recommend anything because I don't know the
internals.  I think asking Neil is the way to go.  I'd love to hear
what he says!

Steve