I have two hard disks on my 2012 Mac Mini. The first disk is partitioned with Mac HD and Data HD. The second drive has OS X Public Beta and Windows partitioned.

I want to prevent OS X on my main disk from auto-mounting OS X Public Beta and Windows 7. Both are encrypted (FileVault 2 and Bitlocker).

I tried to edit /etc/fstab and /private/etc/fstab which seem to be replicated but it doesn't work. I thought I was doing something wrong, so I added a line for Data HD which is not encrypted and it didn't mount.

sudo vifs

UUID=NUMBER none hfs ro,noauto

That's the line I'm issuing for Public Beta. I'm assuming its not hfs because of FV2 so is there another file system I need to enter? I also tried hfs+ and it didn't work, I still get prompted to enter passcode.

For Windows 7, I'm assuming I would use ntfs? I'm not using BootCamp so I don't think it would be fat.

  • Why don't you just keep the drive turned off until you need the Public Beta or Windows? – nohillside Jul 3 '15 at 6:45

Instead of using UUID try using LABEL. This will help to rule out UUID problems.

The following line in /private/etc/fstab stops the drive named SpareSSHD from mounting on OS X 10.10:

LABEL=SpareSSHD none    hfs rw,noauto

My drives are encrypted with FileVault2 and this works.

The following links provide more detail:

/private/etc/fstab and /etc/fstab are the same file. As @forquare confirms, they are symlinked. You can edit either.

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  • You are correct they are the same file, /etc is a symlink to /private/etc as you can see here: lrwxr-xr-x@ 1 root wheel 11B Oct 20 2014 etc@ -> private/etc – forquare Jul 3 '15 at 12:51
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    I'm on OS X 10.11.1 with a configuration like this, and it isn't working for me. I tried using the LABEL form, with the "Volume Name" from Disk Utility, and all the UUIDs associated with it. I still get a "Enter a password to unlock" prompt upon login, though this fstab change prevents the disk from actually mounting once I enter the password to unlock it. Is there another way to do this? Or something else that needs to be used for the LABEL? – Andrew Janke Dec 4 '15 at 1:41

Try 'xx' instead of rw or ro. Since a FV2 drive doesn't mount until you unlock it, the rw,ro won't do anything.

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