What file system is the external drive formatted with and how large are the files you are trying to copy on to it ?
If it is FAT32 or EXFAT there is a known issue that can cause copying large files (over about 1GB, but it depends on your network speed, so the threshold can vary from about 500MB to 2GB) to a Samba share from Windows Explorer on Windows 7 to fail with a timeout during the estimating copy time dialog. (other versions of windows from Vista on are probably affected too)
It seems to be a bug in Samba itself that exhibits on file systems without proper file permissions but I have not been able to find a workaround yet, other than using Ext4 or NTFS as the file system on the drive that is hosting the Samba share - with those it works perfectly.
Ext4 is faster than NTFS on OSMC but if you need to be able to read/write the drive when disconnected and plugged directly into a PC NTFS would be your best option.
Go ext4 since your using a linux platform you will benefit from having a linux filesystem and not a windows proprietary filesystem, remove all your data from the drive since it will wipe your drive
ssh your osmc installation
then sudo fdisk -l
Device Boot Start End Sectors Size Id Type
/dev/sda1 2048 31266815 31264768 14.9G 83 Linux
sudo fdisk /dev/sda
then press d to delete then 1 for the old partition
then n for new partition p for primary partition then 1 for partition number
to check if the partition was created press p
and last but not least w to write changes
Unfortunately on that screen shot what we need to see is before the bit that you have taken a picture of - all that screen shows is that the system shut down into emergency recovery mode, but not what the reason was.
Did you edit /etc/fstab ? If you have edited fstab and created an incorrect entry it can cause the system to fail to boot.
You can boot holding down the shift key on a keyboard which will take you to the OSMC recovery console. From here you could edit /etc/fstab again and remove the incorrect line to get the system booting again.
Don’t mount a hard drive in /var, you should manually mount hard drives in /mnt.
Make sure you always use the nofail option in the fstab line otherwise if the drive cannot be mounted it will prevent the system booting, even though the drive may be a non-critical media drive.
Also make sure that you do actually create the directory for the mountpoint that you are trying to use. So for example if you try to mount to /mnt/hdd then it’s up to you to manually create that directory, eg:
sudo mkdir /mnt/hdd
Because even if your fstab line is correct if the directory doesn’t exist mounting will fail and without the nofail option the system will fail to boot.
One other point I would make is that it’s not necessary to manually mount an external drive at all. Simply remove your fstab entry and it should automatically mount under /media at boot based on the volume name. (or UDID if it doesn’t have a volume name)
So you could be making a lot of unnecessary work for yourself when you could simply plug the drive in and allow it to mount itself under /media.