MacOS – How to set default mount options

automountdisk-volumemacos

I'm trying to figure out where the default mount options are set for user-mounted filesystems (e.g., disk images, USB thumbdrives, etc.). I'm working with OS X 10.11 ("El Capitan").

The options I specify for known disk partitions in /etc/fstab are respected when they're mounted automatically at boot time — or even manually via Disk Utility — but I can't seem to set the default mount options for any "unknown" filesystem that gets automounted in /Volumes.

I've tried changing AUTOMOUNTD_MNTOPTS in /etc/autofs.conf and adding options with -o to the ProgramArguments array of /System/Library/LaunchDaemons/com.apple.automountd.plist (which required disabling SIP), but neither change seems to have any effect.

It would seem that some other set of defaults is being used… but where are those defaults defined?

Best Answer

If I understand your question, you should have a look into /etc/auto_master

This article explains very well how auto-mount works https://useyourloaf.com/blog/using-the-mac-os-x-automounter/

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How does Mac OS X decide which volumes to mount? One of the disks doesn’t mount at boot

OS X uses diskarbitrationd which discovers new storage devices and probes them for mountable filesystems. The Disk Arbitration framework handles notifying applications of disk mount/unmount events, and allows them to influence whether a volume is mounted or not.

Consult the man page for diskarbitrationd for very limited further information; for example, diskarbitrationd consults /etc/fstab to determine if the discovered filesystem should be mounted other than at the default location(/Volumes/) or with special options (or not mounted at all.)

Reasons for diskarbitrationd not mounting a filesystem or "volume" on a device may include:

Errors (corruption) in the partition table.
A mismatch between the partition type and the filesystem.
A damaged filesystem which fsck cannot repair.
Hardware failure.
Filesystem is listed in /etc/fstab with noauto.
An application has used the Disk Arbitration framework to prevent auto-mounting

According to your comments, all your journaled filesystems are mounting, and the filesystem which isn't mounting doesn't have journaling turned on. Journaling was introduced in 10.2 Server and 10.3 Client and by now is considered a vital, critical feature. It should be enabled unless you really know what you're doing; hence why you must hold down the option-key in Disk Utility to disable it in modern versions of OS X. Make sure the volume has journaling enabled:

Select the volume in Disk Utility
Choose File->Enable journaling (if it is greyed out, journaling is enabled.
Verify by choosing File->Get info; you should see "Mac OS Extended (Journaled)" as the filesystem type.

MacOS – How to salvage macos resource forks when copying from a non hybrid ISO 9660 Rockridge CD

If the resource forks are available under the names you're describing, here's a way to recombine them:

cp -a /source/filename /destination/filename
dd if=/source/._filename of=/destination/filename/..namedfork/rsrc

This will still not copy over the type/creator and other Finder metadata, but it will copy over the resource fork.

Best Answer

Related Solutions

How does Mac OS X decide which volumes to mount? One of the disks doesn’t mount at boot

MacOS – How to salvage macos resource forks when copying from a non hybrid ISO 9660 Rockridge CD

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