Hi experts and fellows,

Im running Ubuntu 22.04.3 on an ODROID N2+ SBC from 128GB MMC and having an issue with remounted root filesystem when plugging in an USB Drive.

Situation

"boot" is mounted on /dev/mmcblk1p1
"root" is mounted on /dev/mmcblk1p2

fstab

# UNCONFIGURED FSTAB FOR BASE SYSTEM/dev/mmcblk1p1 /media/boot ext2 errors=continue 0 1/dev/mmcblk1p2 / ext4 errors=remount-ro 0 1/dev/mmcblk1p4 none swap sw 0 0//192.168.1.1/fritz/Seagate_500G /mnt/smb/fritz.box/ cifs vers=3.0,noserverino,credentials=/var/cifscredentials_fritzbox,iocharset=utf8,file_mode=0777,dir_mode=0777 0 0tmpfs /dev/shm tmpfs defaults,rw,nodev,nofail,noatime,nosuid 0 0#/dev/disk/by-id/scsi-SSamsung_SSD_870_EVO_250G_4BBB38EE1A62-part1 /mnt/sda1 ext2 errors=remount-ro 0 1#/dev/sda1 /mnt/sda1 ext2 errors=remount-ro 0 1#/dev/sda2 /mnt/sda2 ext4 errors=remount-ro 0 1#/dev/sda3 /mnt/sda3 ext4 errors=remount-ro 0 1#/dev/disk/by-id/scsi-SSamsung_SSD_870_EVO_250G_4BBB38EE1A62-part2 /mnt/sda2 ext4 errors=remount-ro 0 1#/dev/disk/by-id/scsi-SSamsung_SSD_870_EVO_250G_4BBB38EE1A62-part3 /mnt/sda3 ext4 errors=remount-ro 0 1/dev/disk/by-id/usb-WD_Elements_25A3_56474858304D4A47-0:0-part1 /mnt/sdb1 ext4 errors=remount-ro 0 1/dev/disk/by-id/usb-WD_Elements_25A3_56474858304D4A47-0:0-part2 /mnt/sdb2 ext4 errors=remount-ro 0 1/dev/disk/by-id/mmc-GE4S5_0x1dd86864-part1 /mnt/mmcblk1p1 ext2 errors=remount-ro 0 1/dev/disk/by-id/mmc-GE4S5_0x1dd86864-part2 /mnt/mmcblk1p2 ext4 errors=remount-ro 0 1/dev/disk/by-id/mmc-GE4S5_0x1dd86864-part3 /mnt/mmcblk1p3 ext4 errors=remount-ro 0 1

Results of "df" before SSD is connected

odroid@bonna:~$ dfFilesystem                        1K-blocks      Used  Available Use% Mounted ontmpfs                                375432      3108     372324   1% /run/dev/mmcblk1p2                     61017216  34021000   24468788  59% /tmpfs                               1877144         0    1877144   0% /dev/shmtmpfs                                  5120         4       5116   1% /run/locktmpfs                               1877144        20    1877124   1% /tmp/dev/mmcblk1p1                       245728    187188      45436  81% /media/boot/dev/mmcblk1p3                    174350364        28  165421056   1% /mnt/mmcblk1p3//192.168.1.1/fritz/Seagate_500G  488394008 296031992  192362016  61% /mnt/smb/fritz.box/dev/sda1                        2112647068 354410232 1650846272  18% /mnt/sdb1/dev/sda2                        5620694080 354574192 4982778064   7% /mnt/sdb2/dev/zram1                           738048    147536     536752  22% /opt/zram/zram1overlay1                             738048    147536     536752  22% /var/lib/openhab/persistence/dev/zram2                           996780     44108     883860   5% /opt/zram/zram2overlay2                             996780     44108     883860   5% /var/logtmpfs                                375428       124     375304   1% /run/user/1000

A SSD Drive with same partition table gets recognized as /dev/sda(x).

Problem statement

The root filesystem automatically gets remounted to/dev/sda2immediately when USB SSD drive is connected.

odroid@bonna:~$ dfFilesystem                       1K-blocks      Used Available Use% Mounted ontmpfs                               375432      3128    372304   1% /run/dev/sda2                         61017216  34021016  24468772  59% /tmpfs                              1877144         0   1877144   0% /dev/shmtmpfs                                 5120         4      5116   1% /run/locktmpfs                              1877144        20   1877124   1% /tmp/dev/mmcblk1p1                      245728    187188     45436  81% /media/boot/dev/mmcblk1p3                   174350364        28 165421056   1% /mnt/mmcblk1p3//192.168.1.1/fritz/Seagate_500G 488394008 296031992 192362016  61% /mnt/smb/fritz.box/dev/zram1                          738048    147536    536752  22% /opt/zram/zram1overlay1                            738048    147536    536752  22% /var/lib/openhab/persistence/dev/zram2                          996780     44464    883504   5% /opt/zram/zram2overlay2                            996780     44464    883504   5% /var/logtmpfs                               375428       124    375304   1% /run/user/1000/dev/sda1                           245728    187188     45436  81% /media/usb0/dev/sda2                         61017216  23240956  35248832  40% /media/usb1/dev/sda3                        174350364        28 165421056   1% /media/usb2

Question

What service/configuration is reponsible for this behavior? What can I do to turn off rootfs auto-remount to /dev/sda2?

Cheers