Facing issues while mounting external hard drives

I have connected two external hard drives of 4TB & 1TB capacities respectively to my Raspberry Pi 4B.
Both are formatted with ext4 file systems.
But upon executing the below the drive are not being listed in ‘lsblk’.

dietpi@RaspberryDietPi:~ $ lsblk
NAME        MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
sda           8:0    0 931.5G  0 disk 
└─sda1        8:1    0 931.5G  0 part 
sdb           8:16   0   3.7T  0 disk 
└─sdb1        8:17   0   3.7T  0 part 
mmcblk0     179:0    0  29.8G  0 disk 
├─mmcblk0p1 179:1    0   256M  0 part /boot
└─mmcblk0p2 179:2    0  29.6G  0 part /



dietpi@RaspberryDietPi:~ $ sudo mount /dev/sda1 /media/Intermediary_Cache
mount: /media/Intermediary_Cache: /dev/sda1 is not a valid block device.



dietpi@RaspberryDietPi:~ $ lsblk
NAME        MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
sdb           8:16   0  3.7T  0 disk 
└─sdb1        8:17   0  3.7T  0 part 
mmcblk0     179:0    0 29.8G  0 disk 
├─mmcblk0p1 179:1    0  256M  0 part /boot
└─mmcblk0p2 179:2    0 29.6G  0 part /

After the first drive gets ‘removed’ (still connected to the Pi though), the mounting of the second drive succeeds.

dietpi@RaspberryDietPi:~ $ sudo mount /dev/sdb1 /media/NAS_Media

I also tried to adding the following entries in the /etc/fstab:
UUID=Drive1 UUID* /media/Intermediary_Cache ext4 defaults 0 2
UUID=Drive2 UUID* /media/NAS_Media ext4 defaults 0 2
Although, the above seems to successfully mount both drives after reboot momentarily, but either one of the drives gets unmounted soon after.
I also tried changing the fstab params to ‘noatime,lazytime,rw 0 2’ with similar results.

Also, I tried connecting the drives between different USB ports on the Pi (USB 2/3) & reformatting the drives to different filesystems(NTFS/BTRFS) with similar results as well.

I have tested both the drives on my linux PC simultaneously without any issues.

I am unsure as to what the cause of the issue is. Any help is appreciated.
Thanks

Do these have their own power supplies? That’s the issue I ran into. I bought a splitter cable with a second portion connecting to a USB power adapter and that fixed the issue.

Yes. Both of the the drives are plugged in with their respective power supplies.

can you check for kernel error messages

dmesg -l err,crit,alert,emerg

as well let’s check some information on the drives

lsblk -o name,fstype,label,size,ro,type,mountpoint,partuuid,uuid

did you tried using dietpi-drive_manager to mount your USB drives?

I’ve tried mounting the drives via dietpi-drive-manager but as soon as I execute it in the shell either of the drivers get unmounted

means using drive manager is working fine and you are able to mount both drives?

Not quite.
Whenever I execute dietpi-drive-manager, the console freezes for sometime & when finally the manager is displayed either one of the drives get unmounted & is not visible in drive manager.

Pls can you provide the information I have ask for https://dietpi.com/forum/t/facing-issues-while-mounting-external-hard-drives/5532/4