If fstab is deprecated in Lion (and before, I think?) how does one, properly, prevent a partition from mounting on system boot?

This is loosely related to this question which as of this post has no answer.


So my confusion comes from reading about fstab and being told to edit /etc/fstab.hd. So.../etc/fstab is what I need to create and where I add UUID info to prevent partitions from mounting?

$ cat /etc/fstab.hd 
This file does nothing, contains no useful data, and might go away in
future releases.  Do not depend on this file or its contents.

Neither man fstab nor man diskarbitrationd (see here for example) mention deprecation of /etc/fstab.

It's not there by default, but why should it be, if it just were empty because the defaults are good? It's there if you need it.

Claims of deprecation of fstab has been floating around the web for some time now.

From here:

etc/fstab is deprecated in Leopard

From here:

I was going to suggest editing the /etc/fstab file, but apparently that was deprecated in Leopard, and is probably now removed from Snow Leopard...

Apart from the fact that there is no mention of deprecation in its documentation, why would Apple add utilities for properly editing deprecated configuration files?

Quoting man vifs:

     vifs -- safely edit fstab
     The vifs utility originates from Mac OSX 10.5.

While the following program runs (infinite loop, Ctrl-C to quit), no disk will be mounted, with proper conditions you can control it more fine-grained of course:

#include <CoreFoundation/CoreFoundation.h>
#include <DiskArbitration/DiskArbitration.h>

DADissenterRef BlockMount(DADiskRef disk, void *context)
        DADissenterRef dissenter = DADissenterCreate(kCFAllocatorDefault, kDAReturnNotPermitted, CFSTR("forbidden!"));
        return dissenter;

int main (int argc, const char * argv[])
    DAApprovalSessionRef session = DAApprovalSessionCreate (kCFAllocatorDefault);
    if (!session)
        fprintf(stderr, "failed to create Disk Arbitration session");
        DARegisterDiskMountApprovalCallback(session, NULL, BlockMount, NULL);
        DAApprovalSessionScheduleWithRunLoop(session, CFRunLoopGetCurrent(), kCFRunLoopDefaultMode);

        while (true) {
            CFRunLoopRunInMode(kCFRunLoopDefaultMode, 60 /* seconds */, false);

        DAApprovalSessionUnscheduleFromRunLoop(session, CFRunLoopGetCurrent(), kCFRunLoopDefaultMode);
        DAUnregisterApprovalCallback(session, BlockMount, NULL);
    return 0;

Save as main.c and compile using the following (you need Developer Tools):

cc main.c -o mountstopd -framework Foundation -framework DiskArbitration
  • It's similar with cron. No deprecation, just not used by default. There's a difference. – Daniel Beck Sep 16 '11 at 18:07
  • I'm intentionally not answering the part that's a duplicate of the referenced question. – Daniel Beck Sep 16 '11 at 18:07
  • maybe I'm confused, well, obviously! see edit above. what's difference between /etc/fstab and /etc/fstab.hd`? perhaps this will clear up my confusion. – Meltemi Sep 16 '11 at 19:07
  • 1
    @Meltemi: It's an entirely different file and unrelated. See for example here or here. – Daniel Beck Sep 16 '11 at 19:27
  • ic. i've got it working with /etc/fstab just fine now. thx – Meltemi Sep 16 '11 at 22:33

There is no need to run programs or worry about where fstab is located.

Just run sudo vifs and add the appropriate lines to the file. Mine is:-

# Warning - this file should only be modified with vifs(8)
# Failure to do so is unsupported and may be destructive.
UUID=E00F307A-9295-482E-8A79-2FA2C922F3CD none ntfs rw,noauto
LABEL=Tempy none ntfs rw,noauto

Make sure you know how to modify and save a file in vim. Vimtutor will teach you the basics.

PS /private/etc is actually the same as /etc. OS X processes the url internally (this is explained in API documentation - although I still don't understand why)

  • If you're using a third-part driver such as Paragon NTFS, this technique may not work without modification. For example, I had to use a Label (UUIDs wouldn't work) and the filesystem type had to be ufsd_NTFS instead. It didn't break anything if the more standard options were used, it just didn't work. – Zxaos Sep 10 '13 at 15:35
  • It didn't work for fat32! I tried both UUID and LABEL as well. – Necktwi Jan 18 '17 at 3:05

Since I have same problem, and haven't found any resonable solution for this, I've wrote little launch daemon service that prevents mounting of volumes with specified labels.

Here it is: https://github.com/nanoant/mountblockd

  • 1
    Adaś, in mountblockd, the plist says to enter volume name. But I have two volumes with the same name. Can the plist take UUID instead? – Edward Ned Harvey Dec 19 '14 at 14:48

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