Hi,

this post describes how to setup samba to provide filesystem snapshots to Windows in its “Previous Versions” tab.

Install your prefered Linux Distribution. In this tutorial debian 9 stretch.

Let us assume /dev/sda is the disk for the operating system and /dev/sdb the disk for data. 2 Types of shares should exist. Home shares and project shares. All homes are inclued if a snapshot is triggered (Should demonstrate multiple shares in one subvolume). While each project can have its own snapshots (One share per subvolume).

The previous version feature requieres a filesystem with snapshot support. Linux just support one natively: btrfs. Install btrfs tools/support and gdisk

root@debdev ~ # apt-get install btrfs-progs gdisk samba attr

Prepare your disk. Partition 1 (/dev/sdb1) should hold the homes (mount point /mnt-home) and partition 2 the projects (mount point /mnt-projects). create and format the partitions. I use gpart for partitioning. It creates a GPT based layout but if you have a disk <2TB a MBR layout is also possible.

root@debdev ~ # gdisk /dev/sdb
Command (? for help): n
Partition number (1-128, default 1):
First sector (34-16777182, default = 2048) or {+-}size{KMGTP}:
Last sector (2048-16777182, default = 16777182) or {+-}size{KMGTP}: 1600G
Partition number (1-128, default 2):
...
root@debdev ~ # mkfs.btrfs /dev/sdb1
root@debdev ~ # mkfs.btrfs /dev/sdb2

Create Mountpoints

root@debdev ~ # mkdir /mnt-home
root@debdev ~ # mkdir /mnt-projects

Mount the partitions at boot time. Append the following lines to /etc/fstab

/dev/sdb1 /mnt-home btrfs defaults,noatime,rw 0 0
/dev/sdb2 /mnt-projects btrfs defaults,noatime,rw 0 0

Reboot and check if the partitions are mounted correctly

root@debdev ~ # mount | grep sdb
/dev/sdb1 on /mnt-home type btrfs (rw,noatime,space_cache,subvolid=5,subvol=/)
/dev/sdb2 on /mnt-projects type btrfs (rw,noatime,space_cache,subvolid=5,subvol=/)

Create subvolumes. subvolumes are the basis for snapshots. The root folders of the partitions are already subvolumes but we need additional ones for the snapshots.

root@debdev ~ # btrfs subvolume create /mnt-home/homes 
root@debdev ~ # btrfs subvolume create /mnt-home/.snapshots
root@debdev ~ # btrfs subvolume create /mnt-projects/projects 
root@debdev ~ # btrfs subvolume create /mnt-projects/.snapshots

Additionally I will here describe all steps (for a standalone windows workgroup server) including the creation of user and groups. 2 Users which its own Windows Samba Share and access to one project.

root@debdev ~ # groupadd project1
root@debdev ~ # useradd  -s /bin/false -G users,project1 user1
root@debdev ~ # useradd  -s /bin/false -G users,project1 user2

Add Windows/Samba Users and passwords

root@debdev ~ # smbpasswd -a user1
root@debdev ~ # smbpasswd -a user2

Create folders and set permissions

root@debdev ~ # mkdir /mnt-home/homes/user1
root@debdev ~ # chown user1:user1 /mnt-home/homes/user1
root@debdev ~ # chmod 770 /mnt-home/homes/user1
root@debdev ~ # mkdir /mnt-home/homes/user2
root@debdev ~ # chown user2:user2 /mnt-home/homes/user2
root@debdev ~ # chmod 770 /mnt-home/homes/user2
root@debdev ~ # btrfs subvolume create /mnt-projects/projects/project1
root@debdev ~ # btrfs subvolume create /mnt-projects/.snapshots/project1
root@debdev ~ # chown root:project1 /mnt-projects/projects/project1
root@debdev ~ # chmod 770 /mnt-projects/projects/project1

Move old config

root@debdev ~ # mv /etc/samba/smb.conf /etc/samba/smb.conf.org

Samba example config /etc/samba/smb.conf

[global]
        workgroup = YOURWORKGROUP
        netbios name = yourserver
        server string = Samba Server
        # interfaces = 127.0.0.1, eth0
        # bind interfaces only = Yes
        security = USER
        map to guest = Bad User
        os level = 1
        preferred master = No
        local master = No
        domain master = No
        guest account = nobody
        unix charset = UTF8
        directory mask = 0770
        create mask = 0640
        # inherit permissions = yes
        inherit owner = yes
        client ntlmv2 auth = yes
        client lanman auth = no
        client plaintext auth = no
        # Only ntlmv2
        ntlm auth = yes
        lanman auth = no
        encrypt passwords = yes
        access based share enum = yes
        server signing = auto
        client signing = auto
        vfs objects = acl_xattr
        map acl inherit = yes
        store dos attributes = yes

[project1$]
        path = /mnt-projects/projects/project1
        # Group project1
        valid users = @project1
        # admin users = root, michael
        write list = @project1
        force group = project1
        read only = No
        guest ok = no
        vfs objects = shadow_copy2
        # /mnt-projects/.snapshots/projects/@GMT_2018.10.16-21.31.48
        # shadow:basedir => subvolume
        shadow:basedir = /mnt-projects/projects/project1
        shadow:snapdir = /mnt-projects/.snapshots/project1
        shadow:format = @GMT_%Y.%m.%d-%H.%M.%S
        shadow:sort = desc
        shadow:localtime = no
        directory mask = 0770
        create mask = 0660

[user1$]
        comment = Home User1
        browsable = no
        path = /mnt-home/homes/user1
        writable = yes
        write list = user1
        guest ok = no
        vfs objects = shadow_copy2
        # /mnt-home/.snapshots/@GMT_2018.10.16-21.31.48/user1
        shadow:basedir = /mnt-home/homes
        shadow:share_root = user1
        shadow:snapdir = /mnt-home/.snapshots
        shadow:format = @GMT_%Y.%m.%d-%H.%M.%S
        shadow:sort = desc
        shadow:localtime = no

[user2$]
        comment = Home User2
        browsable = no
        path = /mnt-home/homes/user2
        writable = yes
        write list = user2
        guest ok = no
        vfs objects = shadow_copy2
        # /mnt-home/.snapshots/@GMT_2018.10.16-21.31.48/user2
        # shadow:basedir => subvolume
        shadow:basedir = /mnt-home/homes
        shadow:share_root = user2
        shadow:snapdir = /mnt-home/.snapshots
        shadow:format = @GMT_%Y.%m.%d-%H.%M.%S
        shadow:sort = desc
        shadow:localtime = no

Ok, time to start samba

root@debdev ~ # systemctl enable smbd.service
root@debdev ~ # systemctl start smbd.service

Try to connect to the shares and copy some data

Creating snapshots. Of all homes:

root@debdev ~ # btrfs subvolume snapshot -r /mnt-home/homes /mnt-home/.snapshots/@GMT_`date -u +%Y.%m.%d-%H.%M.%S`

Note: date -u creates a snapshot with UTC Timestamp. Also in smb.conf shadow:localtime has to configure to no

And a Snapshot of project1

root@debdev ~ # btrfs subvolume snapshot -r /mnt-projects/projects/project1 /mnt-projects/.snapshots/project1/@GMT_`date -u +%Y.%m.%d-%H.%M.%S`

Copy more data to the share….and try to access the Previous Version tab.

Some further helpful commands
List all snapshots of a subvolume

root@debdev ~ # btrfs subvolume list /mnt-home/homes

Delete a snapshot

root@debdev ~ # btrfs subvolume delete /mnt-home/.snapshots/@GMT_2018.10.16-21.31.48

Michael