I'm facing into strange behavior. I'm writing to raw device (attached disk in Linux) in python using this code:

with open("/dev/xvdf", 'w') as disk:
    disk.write("aaa")

before I executed this code the disk privileges were:

brwxrwxrwx 1 root disk 202, 80 Apr 23 07:59 /dev/xvdf

After executing this code it changed to:

brw-rw---- 1 root disk 202, 80 Apr 23 07:59 /dev/xvdf

1. Why the file privileges changes after opening the file for writing?
2. Any solution for that? I need to file remain with the same full privileges.

Thanks for your help