I have the following configuration based on this tutorial:

  1. Read/write disk image (macOS Extended [Journaled]) created using Disk Utility called Backup.img which resides on a partition of an external drive; when using a USB connection with the external drive (and mounting the "host" partition), I am able to further mount the disk image and write to its volume.
  2. Samba server on another machine that I use to serve the partition/volume on which the disk image resides. I can access the samba server fine and can see the disk image perfectly intact.


When I mount the disk image (accessing it from Big Sur in Finder after using the "Go To Server" feature to connect to the samba server), I find that I am unable to write to the volume. Moreover, when I "Get Info" on the volume,

enter image description here

I am told that I can only read even though my user is allowed read/write.

thus, I think because of this, I am unable to successfully execute (per the tutorial instruction)

sudo tmutil setdestination /Volumes/MyVolume/

Why is this? I keep wanting to blame it on a permissions issue but then all the permissions look fine when I check them out.

  • 1
    Can you copy a file to the share in finder? Also - how are you determining “ I am told that I can only read even though my user is allowed read/write.”
    – bmike
    Dec 30, 2021 at 15:14

1 Answer 1


Try this basic smb.conf instead.

ea support = yes
mdns name = mdns
security = user
min protocol = SMB2
vfs objects = fruit streams_xattr
fruit:metadata = stream
fruit:model = MacSamba
fruit:posix_rename = yes 
fruit:veto_appledouble = no
fruit:wipe_intentionally_left_blank_rfork = yes 
fruit:delete_empty_adfiles = yes
fruit:time machine = yes
aio read size = 1 
aio write size = 1

comment = Mac Time Machine Backup
path = /srv/smb/mactimemachinebackup
writeable = yes
vfs objects = fruit streams_xattr io_uring
fruit:time machine = yes

Note that vfs_io_uring needs Linux >= 5.1. Backups may happen faster when using vfs_io_uring.


Make sure you have Avahi installed and running for your backup server to automatically appear under Network. There is no need to create special disk images on the share using this configuration. MacOS will do it for you if you are using APFS.

  • Please edit answers based on feedback received in the comments, don‘t just delete and repost them :-) The question doesn‘t mention Linux at all, also if your answer needs to be applied on server side you may want to be more specific about this.
    – nohillside
    Dec 30, 2021 at 11:30

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