Thanks. I appreciate you taking the time to respond. I would like to 
forward this to those that maintain faq/wiki so that some one searches 
gets the info and does not have to bother you. Is that OK?

I normally would go for backup before rebuild, but 15TB disk space is 
too much to come up with, without serious $$ and need. Besides, these 
are movies/recordings for htpc and the data is available on 
dvds/internet. So there is inherent lack of importance. In other words, 
I recommend backup as most do, but it looks like every one has some 
justification not to do, and want some one else to assure them that it 
is ok :-)

Thanks and Regards
Ramesh

On 10/12/2014 03:35 AM, NeilBrown wrote:

On Sun, 12 Oct 2014 00:46:14 -0500 Ram Ramesh [off-list ref] wrote:

quoted

I googled this topic and got differing answers. Some old ones report
horror stories and others suggest rebuild continues after reboot
normally. My array is rebuilding and it will take about 6 days to
complete. I am expecting bad weather in a couple of days and would like
to proactively shutdown the machine and reboot. Is this safe?

If the information is already available in a clear manner, please let me
know.

uname: Linux xxx 3.13.0-37-generic #64-Ubuntu SMP Mon Sep 22 21:28:38
UTC 2014 x86_64 x86_64 x86_64 GNU/Linux
mdadm - v3.2.5 - 18th May 2012

Thanks for your help

It is certainly designed to be safe and my experience is that it is.
However it is difficult to test all corner cases so it is not impossible that
someone what quite work right.
If something does go wrong:
  1/ don't panic
  2/ don't try to --create the array to fix it
  3/ report all details to this list and I'm 99.9% sure I can get your array
     running again with all your data safe.
But I suspect it won't come to that.

NeilBrown