RE: Failed adadm RAID array after aborted Grown operation

[Bob Brand <brand@wmawater.com.au>]

Thanks Wol.

I can't really disagree with anything you've said except to mention that I 
do have a fair bit of experience (20+ years) but it's all been pretty much 
Microsoft/Windows and hardware RAID.

Like I said this device was never meant to be used for critical data - if 
nothing else this has been something of a wake-up call for us.



-----Original Message-----
From: Wols Lists <antlists@youngman.org.uk>
Sent: Sunday, 22 May 2022 11:31 PM
To: Bob Brand <brand@wmawater.com.au>; Reindl Harald 
<h.reindl@thelounge.net>; Roger Heflin <rogerheflin@gmail.com>
Cc: Linux RAID <linux-raid@vger.kernel.org>; Phil Turmel 
<philip@turmel.org>; NeilBrown <neilb@suse.com>
Subject: Re: Failed adadm RAID array after aborted Grown operation

On 22/05/2022 05:13, Bob Brand wrote:
> Unfortunately, restore from back up isn't an option - after all to
> where do you back up 200TB of data? This storage was originally set up
> with the understanding that it wasn't backed up and so no valuable
> data was supposed to have been stored on it. Unfortunately, people
> being what they are, valuable data has been stored there and I'm the
> mug now trying to get it back - it's a system that I've inherited.
>
> So, any help or constructive advice would be appreciated.

Unfortunately, about the only constructive advice I can give you is "live 
and learn". I made a similar massive cock-up at the start of my career, and 
I've always been excessively cautious about disks and data ever since.

What your employer needs to take away from this - and no disrespect to 
yourself - is that if they run a system that was probably supported for 
about five years, then has been running on duck tape and baling wire for a 
further ten years, DON'T give it to someone with pretty much NO sysadmin or 
computer ops experience to carry out a potentially disastrous operation like 
messing about with a raid array!

This is NOT a simple setup, and it seems clear to me that you have little 
familiarity with the basic concepts. Unfortunately, your employer was 
playing Russian Roulette, and the gun went off.

On a *personal* level, and especially if your employer wants you to continue 
looking after their systems, they need to give you an (old?) box with a 
bunch of disk drives. Go back to the raid website and look at the article 
about building a new system. Take that system they've given you, and use 
that article as a guide to build it from scratch. It's actually about the 
computer being used right now to type this message.

I use(d) gentoo as my distro. It's a great distro, but for a newbie I think 
it takes "throw them in at the deep end" to extremes. Go find Slackware and 
start with that. It's not a "hold their hands and do everything for them" 
distro, but nor is it a "here's the instructions, if they don't work for you 
then you're on your own" distro. Once you've got to grips with Slack, have a 
go at gentoo. And once you've managed to get gentoo working, you should have 
a pretty decent grasp of what's going "under the bonnet". CentOS/RedHat/SLES 
should be a breeze after that.

Cheers,
Wol



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