redeploying my raids, I need a review

[DaggyStyle]

Hello All,

following this thread: https://forums.gentoo.org/viewtopic-t-931906-highlight-grub.html I've decided to redeploy my sw raids to I won't have inconsistencies.
I have 4 1TB drives with raid1 on part of them and raid5 on the rest, as I don't have a way to back it up, I've decided to fail one of the drives from the raids and save the root tree on it.

as I didn't done that before, I'd like someone that knows better to review the commands I'm about to use to spot and possible problems.

• md0: raid1 spans over sd{abcd}1 (/boot)
  
• md2: raid1 spans over sd{abcd}3 (/)
  
• md1: raid5 spans over sd{abcd}2 (rest)
  

so I've thought of doing the following:

1. boot sysrescuecd and mount all the partitions.
   
2. for each raid run

   Code:

   mdadm --fail /dev/{md0,md1,md2} /dev/sdd{1,2,3}

   followed by

   Code:

   mdadm -r /dev/{md0,md1,md2} /dev/sdd{1,2,3}

   
   
3. remove the partition table from sdd, recreate a single partition on all the drive and copy the entire fs from the remaining raid by running

   Code:

   find /mnt/gentoo/ -print -depth | cpio -padmuv /mnt/sdd

   
   
4. unmount all beside sdd and blank sb of /dev/{md0,md1,md2} and partition tables on sd{abc}
   
5. create the new layout on sda and save it to file using

   Code:

   sgdisk -b part-table.gpt /dev/sda

   
   
6. run

   Code:

   sgdisk -l part-table.gpt /dev/sd{b,c}

   
   
7. create the arrays again using

   Code:

   mdadm --create --verbose {md0,md1,md2} --level={1,1,5} --metadata={0.9,0.9,1.2} --raid-devices=4 missing /dev/sdd{1,2,3}

   
   
8. recreate the partitions on the raid5, create the fs and mount them back.
   
9. copy the content of /mnt/sdd back to the raid5 using

   Code:

   find /mnt/sdd/ -print -depth | cpio -padmuv /mnt/gentoo

   
   
10. unmount sdd and destroy the partition table.
    
11. run

    Code:

    sgdisk -l part-table.gpt /dev/sdd

    
    
12. add sdd to existing raid by running

    Code:

    mdadm ${md0,md1,md2} --verbose -a /dev/sdd{1,2,3}

    
    
13. run

    Code:

    mdadm --detail --scan >> /mnt/gentoo/etc/mdadm.conf

    and fix it.
    

is what I gonna do is ok? I really don't want to mess things up.
of course I'm not gonna run the cmds like that, I'm going to run it using one entry per input array.
lastly, I'm pretty sure that my copy isn't multithreaded, I'd like to be able to make a backup copy but threaded one.

Thanks.
_________________
Only two things are infinite, the universe and human stupidity and I'm not sure about the former - Albert Einstein

[frostschutz]

So what you want to do in the end is change the size of each partition/array or what? because the way I read your commands, you'd end up creating the same structure you already have, by throwing your redundancy away, using dangerous copy operations in between, possibly mangling your data, etc. and all of that without having a proper backup. I hope your data isn't important or anything...

[DaggyStyle]