Long-shot: repeatable macOS samba share unmounting during Lightroom import

[Chris Gordon]

WARNING:  Mostly deviating from a FreeBSD specific discussion.

> On Nov 23, 2019, at 9:33 PM, Andrew Reilly <areilly at bigpond.net.au> wrote:
> 
> Hi all,
> 
> This is a long-shot question, because it involves a lot of moving
> pieces, most of which are opaque commercial, poorly documented
> things.  Never the less, it does involve FreeBSD-stable as one of
> the players, and my experience over the years has been that FreeBSD
> folk are both knowledgeable and helpful, so here's hoping.  Herwith
> my tale of computer-induced irritation:
> 
> The story takes place at home, where the FreeBSD system in question
> is a local network file server.  The FreeBSD tracks -STABLE every
> week.  It boots from ZFS on NVM flash and has four 4TB Hitachi ATA
> drives in a RAIDZ.  The current motherboard has a Ryzen 7 1700
> 8-core locked at 3GHz by the bios to avoid a problem of going to
> sleep permanently by failing to come out of some sort of low-power
> state.  It has 32G RAM.  It has intel "PRO/1000 PCI-Express Network
> Driver" network connected to a simple gigabit switch, with both
> IPv4 and IPv6 configured and working.
> 
> The other protagonist in this tale, also connected to the gigabit
> LAN, is an iMac running current-Catalina on APFS flash, mounting
> three filesystems over SMB, from Samba 4.10.10.  After appropriate
> Samba tweaking this seems to be at least as reliable as it ever was
> with netatalk or NFS, and apparently better supported by Apple.
> 
> I keep my Lightroom Classic catalogue on the mac's local (flash)
> drive, but the photo storage is on the network.  The Import Backups
> directory is also on (a different) network drive.  I use Lightroom's
> Import function to copy photos off SD cards using the mac's built-in
> SD card reader and register with the catalogue.  So far so normal,
> I think.
> 
> The problem arose about ?three or four? months ago: could be
> coincident with OS or Lightroom upgrades, I can't remember, but I
> haven't changed anything about the setup, configuration or workflow.
> Now, every single time Lightroom does an import, while it's doing
> the first scan of the SD card to identify photos that it's seen
> before, all three of the Samba filesystems unmount from the mac,
> silently.  I can find no record of error in any of the logs,
> suggesting that the system thinks that it happened deliberately.
> Needless to say, this throws out the import workflow, although it
> manages to pick itself up OK if I just re-mount everything.
> 
> Anyone have any similar experiences?  Any thoughts of where I could
> poke it to find out why this might be happening?  It feels like a
> time-out bug somewhere, but (a) there is no complaint, and (b) the
> network traffic is light at the time.  Needless to say Apple
> documentation is useless.
> 
> Probably another good reason to find an alternative to Lightroom...

Other than the hardware specifics, I have the same exact workflow and same players involved.

Maybe an odd question, but how are you mounting the SMB shares?

Since updating to Catalina, I've found lots of problems dealing with SMB using the Finder window and the items under the Locations side bar.  For instance:
- Mount a share.  At some point overnight when nothing is using it, the share is unmounted.  I can't find anything in the logs to say why, when, what, etc.  Just unmounted.
- With a fresh start of the Finder process and I can access the SMB server/shares.  After some time, activity, something, I only get "Connection Failed" and can't access anything.  What's really crazy, is that I can't even unmount mounted shares from under Locations when it gets in this state (I can unmount via right click on the desktop item, CLI, etc).  I see the share with the eject button, but just get useless error message (if anything).
- Killing (killall -HUP Finder) makes everything work again for a short bit.

If I mount the share via the Finder menubar (Go -> Connect to Server) everything works and is rock solid.  Mounts with no problems, no mystery unmount, etc.  I did test a Lightroom import and had no SMB issues when the shared where mounted via the menu bar.

I also store all of my music on the server and access it via SMB mounts.  I've noticed that the Apple Music app will automatically mount the SMB share when I hit play.  Unlike iTunes, I assume it's more aware of the filesystem and mounts.  Even with the Finder window off in la-la land, the auto-mount by Music works fine. Now if this behavior could only be exposed to every other app....

My completely un-researched guess is that when they removed the NetBIOS support (one of the changes in Catalina), some bug was introduced or uncovered causing the problematic behavior.  My guess ins based on the assumption that the Finder window (not sure what to call it) displays all of the network browsing and discovery and  is the code path that was impacted by the NetBIOS change.  Any mount tied in with this path gets impacted, and when this goes south, it takes the mounts with it.  Mounting via other means doesn't bring in the associated path.

I will check each new OS X update to see if this issue goes away.  Until then, I just mount my shares via "Go- > 'Connect to Server'".   Also note that you can re-enable NetBIOS support in Catalina (https://medium.com/@gobinathm/how-to-access-smb-printer-shares-in-macos-catalina-10-15-17ea91d2c10b).  I've not done nor tested that.

Hopefully a minor tweak to how you mount the SMB share will save you the huge hassle of changing out tools.

Hope that helps.

Chris