Frustration with using Samba as Time Machine

Hi guys

I've been running netatalk on my T50 for the last few years for Time Machine backups. As Samba now has support for TM I wanted to see if I could switch to using it for both my Windows and Mac backups so I could retire Netatalk.

While the setup went fine I have this issue that I can't seem to fix. I can create the initial backup no problem (from a Sierra machine) but subsequent backups fail instantly with an error that the backup disk isn't available. If I connect to the server in Finder with the correct login I can see the shares so authentication is working. But if I try to mount the Time Machine folder it disappears. If I delete the sparsebundle containing the backup I can be mounted fine again. So the existence of the backup is the root problem. But why?

I tried many configs following the advice of others with similar problems (error 13 when trying to mount after the initial backup) but none of the suggestions have worked so far.

Has anyone had this issue and could offer some advice about how to get this working? I've rolled back to my previous config so I don't have my last smb.conf but as an example of what I have tried, I took the config from this thread in it's entirety, changing only the share path and user and it still failed in the exact same way.

None of the guides I read mentioned having to download the vfs modules for Samba, but I've done this.

Howdy, I haven't seen your issue, but happy to share my working smb.conf. Samba is version 4.11.

Also, make sure you have avahi working, TM doesn't work for me without it.

smb.conf:

#======================= Global Settings =======================

[global]

## Browsing/Identification ###

# Change this to the workgroup/NT-domain name your Samba server will part of
   workgroup = WORKGROUP

# server string is the equivalent of the NT Description field
	server string = %h server (Samba, Ubuntu)

# Windows Internet Name Serving Support Section:
# WINS Support - Tells the NMBD component of Samba to enable its WINS Server
   wins support = no

# WINS Server - Tells the NMBD components of Samba to be a WINS Client
# Note: Samba can be either a WINS Server, or a WINS Client, but NOT both
;   wins server = w.x.y.z

# This will prevent nmbd to search for NetBIOS names through DNS.
   dns proxy = no

#  server signing = Mandatory
  server min protocol = NT1
#  server max protocol = SMB3_11
#  client min protocol = SMB1
# client max protocol = SMB3

#  nt pipe support = no
  multicast dns register = yes

#### Networking ####

# The specific set of interfaces / networks to bind to
# This can be either the interface name or an IP address/netmask;
# interface names are normally preferred
;   interfaces = 127.0.0.0/8 eth0

# Only bind to the named interfaces and/or networks; you must use the
# 'interfaces' option above to use this.
# It is recommended that you enable this feature if your Samba machine is
# not protected by a firewall or is a firewall itself.  However, this
# option cannot handle dynamic or non-broadcast interfaces correctly.
;   bind interfaces only = yes
fruit:aapl = yes
fruit:advertise_fullsync = true


#### Debugging/Accounting ####

# This tells Samba to use a separate log file for each machine
# that connects
   log file = /var/log/samba/log.%m

# Cap the size of the individual log files (in KiB).
   max log size = 1000

# If you want Samba to only log through syslog then set the following
# parameter to 'yes'.
#   syslog only = no

# We want Samba to log a minimum amount of information to syslog. Everything
# should go to /var/log/samba/log.{smbd,nmbd} instead. If you want to log
# through syslog you should set the following parameter to something higher.
   syslog = 0

# Do something sensible when Samba crashes: mail the admin a backtrace
   panic action = /usr/share/samba/panic-action %d


####### Authentication #######

# Server role. Defines in which mode Samba will operate. Possible
# values are "standalone server", "member server", "classic primary
# domain controller", "classic backup domain controller", "active
# directory domain controller".
#
# Most people will want "standalone sever" or "member server".
# Running as "active directory domain controller" will require first
# running "samba-tool domain provision" to wipe databases and create a
# new domain.
   server role = standalone server
   client ntlmv2 auth = yes

# If you are using encrypted passwords, Samba will need to know what
# password database type you are using.
   passdb backend = tdbsam

   obey pam restrictions = yes

# This boolean parameter controls whether Samba attempts to sync the Unix
# password with the SMB password when the encrypted SMB password in the
# passdb is changed.
   unix password sync = yes

# For Unix password sync to work on a Debian GNU/Linux system, the following
# parameters must be set (thanks to Ian Kahan <<kahan@informatik.tu-muenchen.de> for
# sending the correct chat script for the passwd program in Debian Sarge).
   passwd program = /usr/bin/passwd %u
   passwd chat = *Enter\snew\s*\spassword:* %n\n *Retype\snew\s*\spassword:* %n\n *password\supdated\ssuccessfully* .

# This boolean controls whether PAM will be used for password changes
# when requested by an SMB client instead of the program listed in
# 'passwd program'. The default is 'no'.
   pam password change = yes

# This option controls how unsuccessful authentication attempts are mapped
# to anonymous connections
   map to guest = bad user

########## Domains ###########

#
# The following settings only takes effect if 'server role = primary
# classic domain controller', 'server role = backup domain controller'
# or 'domain logons' is set
#

# It specifies the location of the user's
# profile directory from the client point of view) The following
# required a [profiles] share to be setup on the samba server (see
# below)
;   logon path = \\%N\profiles\%U
# Another common choice is storing the profile in the user's home directory
# (this is Samba's default)
#   logon path = \\%N\%U\profile

# The following setting only takes effect if 'domain logons' is set
# It specifies the location of a user's home directory (from the client
# point of view)
;   logon drive = H:
#   logon home = \\%N\%U

# The following setting only takes effect if 'domain logons' is set
# It specifies the script to run during logon. The script must be stored
# in the [netlogon] share
# NOTE: Must be store in 'DOS' file format convention
;   logon script = logon.cmd

# This allows Unix users to be created on the domain controller via the SAMR
# RPC pipe.  The example command creates a user account with a disabled Unix
# password; please adapt to your needs
; add user script = /usr/sbin/adduser --quiet --disabled-password --gecos "" %u

# This allows machine accounts to be created on the domain controller via the
# SAMR RPC pipe.
# The following assumes a "machines" group exists on the system
; add machine script  = /usr/sbin/useradd -g machines -c "%u machine account" -d /var/lib/samba -s /bin/false %u

# This allows Unix groups to be created on the domain controller via the SAMR
# RPC pipe.
; add group script = /usr/sbin/addgroup --force-badname %g

############ Misc ############

# Using the following line enables you to customise your configuration
# on a per machine basis. The %m gets replaced with the netbios name
# of the machine that is connecting
;   include = /home/samba/etc/smb.conf.%m

# Some defaults for winbind (make sure you're not using the ranges
# for something else.)
;   idmap uid = 10000-20000
;   idmap gid = 10000-20000
;   template shell = /bin/bash

# Setup usershare options to enable non-root users to share folders
# with the net usershare command.

# Maximum number of usershare. 0 (default) means that usershare is disabled.
;   usershare max shares = 100

# Allow users who've been granted usershare privileges to create
# public shares, not just authenticated ones
   usershare allow guests = yes

#======================= Share Definitions =======================

# Un-comment the following (and tweak the other settings below to suit)
# to enable the default home directory shares. This will share each
# user's home directory as \\server\username
[homes]
   comment = Home Directories
   browseable = yes
	vfs objects = fruit
	fruit:aapl = yes
	ea support = yes

# By default, the home directories are exported read-only. Change the
# next parameter to 'no' if you want to be able to write to them.
   read only = no

# File creation mask is set to 0700 for security reasons. If you want to
# create files with group=rw permissions, set next parameter to 0775.
  create mask = 0775

[Timemachine]
path = /mnt/3gbdrive/Backups/Timemachine
  browseable = yes
  writeable = yes
#  guest ok = no
  create mask = 0600
  directory mask = 0700
  spotlight = yes
  vfs objects = catia fruit streams_xattr
  ea support = yes
  fruit:aapl = yes
  fruit:time machine = yes

Thanks for the help jdwl101!

As it turns out there must have been something wrong with my system. Shortly afterwards I was unable to ssh into it after a reboot. As video output isn't working yet for the T50 I was unable to see what was wrong so I just restored the SD card from an old image and updated everything to the current versions. That fixed the issue I was having with being unable to run subsequent backups.

Then I got stuck for a while trying to successfully restore the backups. After a few days spent trying to troubleshoot this (as it takes time to run a full backup/restore) it turned out that trying to restore to a USB stick was the problem. Once I grabbed a USB dock and a hard disk the restores worked fine. Now that it seems to be working, I've started a full backup from my main machine to the new share (which will be an overnight job).

In the end, here's the lines I added to my smb.conf to enable Time Machine:

[global]
   fruit:aapl = yes
   fruit:advertise_fullsync = true

[Time Machine]
   path = /Disk2/TM
   browseable = yes
   read only = no
   valid users = timemachine
   vfs objects = catia fruit streams_xattr
   fruit:time machine = yes
   fruit:metadata = stream
   inherit acls = yes