Mac – tradeoffs of iSCSI vs. AFP when using Time Machine with a NAS

I had the same problem with my new macbook pro running OSX Mavericks 10.9.1 and a QNAP TS-219P with firmware 4.0.2.

In the end I had to bypass the Time Machine GUI and set the backup volume through the command line using this command:

sudo tmutil setdestination -ap afp://TimeMachine@NAS.local/TMBackup

where NAS.local is the network name of my QNAP. Once that way set the backups worked fine and the GUI responds properly also.

*** the afp:// part of the above command can just be used in the "Connect to Server" menu item from the Finder. I found that the use of the username "TimeMachine" made all the difference, given that I also use the same network server for my normal network shares.

Better later than never, here is a hack to achieve this :

sudo ifconfig lo0 alias 127.0.0.2/32

Plug your usb drive, then via System Preferences / Sharing add a smb share to a folder time-machine-macbook in the drive time-machine-usb Then, add a destination backup (Time Machine will see it as a network share)

sudo tmutil setdestination -a "smb://user:password@127.0.0.2/time-machine-macbook"

You can see if it's ok with:

tmutil  destinationinfo
> ==================================================
Name          : time-machine4
Kind          : Network
URL           : smb://kenji@realserver._smb._tcp.local./time-machine
ID            : D820D053-C74A-4A06-A7E1-E60C8EA7934F
====================================================
Name          : time-machine-macbook
Kind          : Network
URL           : smb://user@127.0.0.2/time-machine-macbook
Mount Point   : /Volumes/time-machine-macbook
ID            : F707BD0B-64DF-4DB6-A3B7-824470FB5EB2

Then start a backup with tmutil startbackup and mount will show:

/dev/disk3s1 on /Volumes/time-machine-usb (apfs, local, nodev, nosuid, journaled, noowners)
//user@127.0.0.2/time-machine-macbook on /Volumes/time-machine-macbook (smbfs, nobrowse)

You can see detailed progress with tmutil status:

Backup session status:
{
    BackupPhase = Copying;
    ClientID = "com.apple.backupd";
    DateOfStateChange = "2018-06-28 17:38:21 +0000";
    DestinationID = "F707BD0B-57DC-4DB6-A3B7-824470FB5EB2";
    DestinationMountPoint = "/Volumes/Time Machine Backups";
    FirstBackup = 1;
    Percent = "0.08711567546702646";
    Progress =     {
        TimeRemaining = 32679;
        "_raw_totalBytes" = 355694600192;
        bytes = 34429528173;
        files = 887351;
        totalBytes = 391264060211;
        totalFiles = 2922384;
    };
    Running = 1;
    Stopping = 0;
    "_raw_Percent" = "0.09679519496336274";
}

In my case, near 1000000 files were done in about two hours (USB2 disk penalty, versus more than 8 hours via Wi-Fi), I calculate percentages with a small script:

tm-progress.sh
Files : 918702 / 2922384 (31.43%) - Bytes : 32.21 GiB / 364.39 GiB (8.84%)

We can here that many files can make Time Machine to progress "slowly" in Bytes, but nearly 1/3 of files have been copied.

Next step, when backup is finished, plug the usb drive to your realserver and copy the sparsebundle over the "uncompleted one" (or in the shared folder). Of course, Time Machine should be disabled during this step to prevent mounting a partially copied sparsebundle (and maybe corrupting it)

I have used an apfs drive to benefit of snapshots (to be able to revert to a previous "backupdb" in case of sparsebundle corruption, not tested yet)

Edit: even faster mode :

Once the backup has reached BackupPhase = Copying to make it faster you can make the backupbundle mount directly (without sending every operation through smb) by canceling the backup, renaming My-Computer.backupbundle to something like 1My-Computer.backupbundle, and creating a symbolic link :

ln -s /Volumes/time-machine-usb/1My-Computer.backupbundle /Volumes/time-machine-macbook/My-Computer.backupbundle

This tricks timemachine into following the link to the backupbundle localy, and not mount it through smb, which speeds up the backup. Make sure you move the backupbundle back when you have finished your local backup.