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Changing My RAID Array, Removing And Partitioning Block Device

I'm attempting to shape my RAID to an all 2TB 3-block device array. My
current array is as follows:

/dev/sda1        3TB          active          clean     ==>>   
/dev/sda1          796GB
                                                                                             
/dev/sda2              2TB
/dev/sdc1        2TB          active          clean
/dev/sdd1        2TB          active          clean
/dev/sde          1TB          active          clean     ==>>   --fail
then --remove

My goal is to end up with a 4TB RAID array with 3 devices. Then use the
"free" partitions /dev/sde and /dev/sda1 to create another RAID array later.

$mdadm /dev/md127 --fail /dev/sda1             ##to set the block device
as fail

$mdadm /dev/md127 --remove /dev/sda1            ##to remove the block
device from the array

$mdadm --detail /dev/md127              ##to check the array status,
note the status of each of the component devices

You should see that one block device is removed now. I can start
partitioning /dev/sda1 with fdisk.

$fdisk /dev/sda                  ##to load the device

If you have not used fdisk before, it is command line only but
everything is easy to get.

$ sudo fdisk /dev/sda                        ##to load the device, give
your root password
[sudo] password for donato:

Welcome to fdisk (util-linux 2.31).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.


Command (m for help): m  <return>
Help:

  Generic
   d   delete a partition
   F   list free unpartitioned space
   l   list known partition types
   n   add a new partition
   p   print the partition table
   t   change a partition type
   v   verify the partition table
   i   print information about a partition

  Misc
   m   print this menu
   x   extra functionality (experts only)

  Script
   I   load disk layout from sfdisk script file
   O   dump disk layout to sfdisk script file

  Save & Exit
   w   write table to disk and exit
   q   quit without saving changes

  Create a new label
   g   create a new empty GPT partition table
   G   create a new empty SGI (IRIX) partition table
   o   create a new empty DOS partition table
   s   create a new empty Sun partition table

Create a new empty GPT partition table.  This will set up deletion of
all partitions and data on the device. Only when you type w is
everything written to disk. So think before typing w.
I want to add a new partition. Type n to create a partition. I want to
have a 2TB partition and the rest to another partition.
When asked for the type, type 29. I'm going to use these partitions in
an array.

Command (m for help): p
Disk /dev/sda: 2.7 TiB, 3000592982016 bytes, 5860533168 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disklabel type: gpt
Disk identifier: C8877BCC-89D4-F84A-A427-46A4D2886055

Device          Start        End    Sectors   Size Type
/dev/sda1  4294969344 5860533134 1565563791 746.5G Linux RAID
/dev/sda2        2048 4294969343 4294967296     2T Linux RAID

Partition table entries are not in disk order.

The partition seemed fine to me. So I made it permanent by typing w then
q to exit fdisk.

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