Time Machine Backups on OpenBSD with Netatalk¶
May 22, 2019
Table of Contents
Apple’s automatic backup app Time Machine is a fantastic utility that does hourly, daily, and weekly backups of local snapshots. This enables you to restore the system to a previous state in the event of a catastrophic failure—a somewhat rare occurence on the ever-so-stable macOS. The caveat being that storage is limited to AFP (Apple Filing Protocol) compatible devices like the Apple AirPort Time Capsule. Fortunately, Netatalk provides an open source AFP file server that works flawlessly on OpenBSD, and setup is trivial.
Like most apps, installation is made super simple with OpenBSD’s
# pkg_add netatalk quirks-3.124 signed on 2019-04-15T12:10:16Z Ambiguous: choose package for netatalk a 0: <None> 1: netatalk-2.2.6 2: netatalk-2.2.6-avahi 3: netatalk-3.1.12 Your choice: 3 netatalk-3.1.12:libevent-2.0.22p1: ok netatalk-3.1.12: ok The following new rcscripts were installed: /etc/rc.d/netatalk See rcctl(8) for details.
Choose the 3.1.x option, as at May 2019 that’s option 3.
There are not a lot of steps involved; but we first need to enable the dameons before configuring some server side options. Use the
# rcctl enable messagebus avahi_daemon netatalk # rcctl order messagebus avahi_daemon netatalk
Netatalk is configured in
/etc/netatalk/afp.conf and there are myriad options available so I advise you read the afp.conf man page but you can have a running setup with a fairly minimal configuration. I opted to create a new user specially for Time Machine, but this isn’t required:
[Global] vol preset = default_for_all_vol hostname = t420bsd log file = /var/log/netatalk.log mimic model = Xserver keep sessions = yes [default_for_all_vol] file perm = 0664 directory perm = 0774 cnid scheme = dbd [TimeMachine] time machine = yes path = /home/timemachine vol size limit = 500000 valid users = timemachine
The options are mostly self-explanatory, and the afp.conf man page is quite exhaustive, but the gist of it is that global defaults are applied through the
[default_for_all_vol] label that sets permissions and database access restrictions, then a specific
TimeMachine service is created that maps to the
/home/timemachine directory for the one user
timemachine with a maximum disk size of 500 GB—this doesn’t need to be the actual disk size, in fact its purpose is to limit Time Machine to only using x amount of disk space otherwise it will use up the entire disk.
adduser to create the
timemachine account that has authorised
access to the fileserver:
# adduser Use option ``-silent'' if you don't want to see all warnings and questions. Reading /etc/shells ; Check /etc/master.passwd Check /etc/group Ok, let's go. Don't worry about mistakes. There will be a chance later to correct any input. Enter username : timemachine Enter full name : Time Machine Enter shell bash csh ksh nologin sh [ksh]: Uid : Login group timemachine [timemachine]: Login group is ``timemachine''. Invite timemachine into other groups: guest no [no]: Login class authpf bgpd daemon default pbuild staff unbound [default]: Enter password : Enter password again : Name: timemachine Password: **** Fullname: Time Machine Uid: 1002 Gid: 1002 (timemachine) Groups: timemachine ; Login Class: default HOME: /home/timemachine Shell: /bin/ksh OK? (y/n) [y]: Added user ``timemachine'' Copy files from /etc/skel to /home/timemachine Add another user? (y/n) [y]: n Goodbye!
Now, simply start the daemons:
# rcctl start messagebus avahi_daemon netatalk
And that’s it for server side setup; time to move onto your macOS client.
Drop into a terminal, and enter the following command to allow macOS to show unsupported—or non-proprietary Apple appliances such as the Time Capsule—network drives:
$ defaults write com.apple.systempreferences TMShowUnsupportedNetworkVolumes 1
If this will be the first time performing a snapshot and backup of your macOS system, it’s highly advisable you disable CPU throttling for low priority processes by entering the following in your terminal—it will speed up the process exponentially!
$ sudo sysctl debug.lowpri_throttle_enabled=0 Password: debug.lowpri_throttle_enabled: 1 -> 0
Now open Time Machine, and when you hit Select Disk... you should find your file server available—in the abovementioned setup as
It’s equally advisable you re-enable throttling once your first backup is complete, as it
also impacts other system processes—processes that you might not want consuming valuable
system resources. This can be done with
Alternatively, it will automatically reactivate next system restart.