Samba local copy speed & 'insufficient disk space'

Question

I have Ubuntu Server 16.04 installed with Samba on another computer in my network. The Ubuntu OS is on a small SSD and I have 2 additional harddrives mounted to /media/drive1 and /media/drive2.

Now I as far as I know I have 2 options in making these drives accessible from my Windows PC:

• Make 2 Samba shares, one for each drive
• Make 1 Samba share, of the complete /media/ folder

Currently my goal is to copy data from drive 1 to drive 2 (so locally on the server), from the comfort of Explorer on my Windows desktop.

If I make 2 shares, one for each drive, the local copy speed is simply impossible to work with. It ranges around 20-50 KB/s with rare spikes to 1-1.5 MB/s and every 20 or so seconds it just dies and stalls at 0.

From what I've read I now assume this is because the files first have be copied to my windows desktop and be re-uploaded to the server. I guess that 2 shares aren't interpreted as 'local' anymore. Why it completely stalls out though I don't understand.

If I make 1 share, with the entire /media/ directory, I get problems with 'insufficient disk space' when trying to copy files from drive 1 to drive 2, even though there is plenty space. I can copy 80 GB at a time, but never more than 80 GB at once. The speed when copying this way is normal though, around 70-80 MB/s with some spikes to 90 MB/s +.

I now discovered that this happens because Samba checks the available space on drive of the directory you point at, in this case /media, and this folder is on the small SSD. The SSD only has 80 GB free space, so the math checks out.

So I guess the question is, any way to solve this so I can have the best of 2 worlds? I'd like to be able to copy files within the server from one disk to the other without having these limitations, from the comfort of my desktop windows explorer.

Appendix: This is the template I use to create my shares in smb.conf The authentication and access and such all work, no issues.

[Drive1]
    comment = Drive1
    path = /media/drive1
    browsable = yes
    guest ok = no
    valid users = @samba
    read only = no
    create mask = 0755

Answer 1

It will be nasty workaround: create file /usr/local/bin/dfree_Drive.sh

#!/bin/bash
df | egrep '/media/drive[0-9]+$' | awk '{total+=$2; avail+=$4; print $0} END{print total, avail}'

and make it executable. Then in share section of your samba configuration add:

    dfree command = /usr/local/bin/dfree_Drive.sh

This solution is nasty, because it lies to client about capacity of shared volume. But as far as I know there is no way to make samba aware of capacity of specific folder (in contrast to volume).