python3/bash + how to automate creation of disk partitions in Linux - python-3.x

Question

here is example from our rhel server machine
lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sdb 8:16 0 20G 0 disk /data/sdb
sdc 8:32 0 20G 0 disk /data/sdc
sdd 8:48 0 20G 0 disk /data/sdd
sde 8:64 0 20G 0 disk /data/sde
sdf 8:80 0 42G 0 disk
sdg 8:96 0 42G 0 disk
sdh 8:112 0 42G 0 disk
we want to Create a Disk Partitions for the other disks as sdf,sdg,sdh , but all this process should be by bash script and we want to automate the process
first here is example how to create 2 partitions for sdf disk ,
so in this example we create two partitions each one will get 10G size
step 1 ( create partitions when each partition take 10G )
parted /dev/sdf
GNU Parted 3.1
Using /dev/sdf
Welcome to GNU Parted! Type 'help' to view a list of commands.
(parted) mklabel msdos <-- sending text (1)
(parted) mkpart primary 0 10024MB <-- sending text (2)
Warning: The resulting partition is not properly aligned for best performance.
Ignore/Cancel? I <-- sending text (3)
(parted) mkpart primary 10024MB 20048MB <-- sending text (4)
(parted) quit <-- sending text (5)
Information: You may need to update /etc/fstab.
and now we get ( the expected results )
lsblk
sdf 8:80 0 42G 0 disk
├─sdf1 8:81 0 9.3G 0 part
└─sdf2 8:82 0 9.3G 0 part
can we automate the parted process ? or maybe by other approach ( for example by fdisk ) ?
in order to use this automated process in python3/bash script
Note - we not have expect on our Linux machines
reference - https://www.tecmint.com/create-disk-partitions-in-linux/

Answer 1

The parted option --script is what you are looking for.
Create a text file with the parted commands you want to execute (simulate interactive) and use the above option on the command line in the following manner:
parted --script ${batch_file}
I would do that for only one partition at at time until the batch_file content is verified to be correct and reliable.
One observation: you may want to modify
mkpart primary 0 10024MB
to show
mkpart primary 0 10080MB
to eliminate the mis-alignment being reported (disk access performance hit from mis-alignment).
The approach is to calculate a number that is a multiple of 512 bytes, but divisible by 2048 or 4096 depending on what the disk reports is the physical sector size. For example:
4096 * 1024 * (2048 + 256 + 128 + 64 + 32 - 16 + 8) = 1279918080
1279918080 / (1024 * 1024) = 10080 GB