What are directories /Volumes/Untitled* (Yosemite)?

I've just started using a new MacBook Pro, which has Mac OS X 10.10.1 "Yosemite" pre-installed. I was surprised to find paths like /Volumes/Untitled in my /Volumes directory.

% ls -ld /Volumes/Untit*
d--x--x--x+ 3 root  admin  102 17 Dec 17:10 /Volumes/Untitled
d--x--x--x+ 3 root  admin  102 18 Dec 12:34 /Volumes/Untitled 1
d--x--x--x+ 3 root  admin  102 19 Dec 11:44 /Volumes/Untitled 2
d--x--x--x+ 3 root  admin  102 20 Dec 11:45 /Volumes/Untitled 3
d--x--x--x+ 3 root  admin  102 22 Dec 07:17 /Volumes/Untitled 4
d--x--x--x+ 3 root  admin  102 25 Dec 22:23 /Volumes/Untitled 5
d--x--x--x+ 3 root  admin  102 26 Dec 10:41 /Volumes/Untitled 6

Each directory appears to be empty, except for an empty .Trashes subdirectory:

% sudo ls -lR /Volumes/Untitled
total 0
d-wx-wx-wt@ 2 root  admin  68 17 Dec 17:08 .Trashes

/Volumes/Untitled/.Trashes:

I am familiar with entries in /Volumes/* being paths to external storage volumes. I have an external solid-state drive (SSD) mounted, and it has its own named /Volumes/mySSD entry. I have a couple of drives mounted from a file server, and they have their own named /Volumes/serverA etc. entries. In previous Macs and previous Mac OS X versions, I didn't see entries like /Volumes/Untitled.

The timestamps on the Untitled* directories are interesting. The first one is from about when I unpacked the new MacBook Pro for the first time. The most recent one is from about when I started up the computer this morning. If I notice changes in the days ahead, I'll update this question.

I do not see other answers on AskDifferent explaining entries like these. There are answers like Problems creating Yosemite USB bootable drive which mention paths like /Volumes/Untitled 2, but those appear to be paths for actual mounted disk devices that happen to have no volume label. I also have a query in to Apple Support. If they tell me something useful, I'll post it as an answer.

Update 1: A few answers to questions, and further details that seem relevant:

Q: Can you run mount to see whether/which of these mount points actually point to an existing drive? A: I did so, and got this:

% mount
/dev/disk1 on / (hfs, local, journaled)
devfs on /dev (devfs, local, nobrowse)
map -hosts on /net (autofs, nosuid, automounted, nobrowse)
map auto_home on /home (autofs, automounted, nobrowse)
localhost:/TdCrZmzerGhdW5I605Hbd7 on /Volumes/MobileBackups (mtmfs, nosuid, read-only, nobrowse)
//userme@Gemini%28AFP%29._afpovertcp._tcp.local/Qmultimedia on /Volumes/Qmultimedia (afpfs, nodev, nosuid, mounted by userme)
//userme@Gemini%28AFP%29._afpovertcp._tcp.local/serverA on /Volumes/serverA (afpfs, nodev, nosuid, mounted by userme)
/dev/disk2s1 on /Volumes/mySSD (hfs, local, nodev, nosuid, journaled)

Q: Do you have a camera card in the slot, or other computers/devices on the network sharing their content? A: No camera card. Yes, other devices, as noted above: an external SSD, and a couple of drives mounted from a file server.

Also relevant: the external SSD drive has two partitions. One is HFS+ formatted, and is labelled "mySSD" [exact name changed to preserve privacy]. The other partition is ext2 formatted by a Linux system, and as far as I can tell it has no volume label. It's visible from Disk Utility, but doesn't mount as a Mac volume. The drive is connected by USB to the MacBook Pro.

Also relevant: I used Migration Assistant to bring my environment from a Time Machine backup of an older Mac to this computer. I migrated users, applications, system settings, and other files. Among the software installed on the old computer was fuse-ext2 0.0.7, a utility to let Mac OS computers mount ext2 partitions. This software was running on the new computer:

% fuse-ext2 --version
[...snip...]
fuse-ext2 0.0.7 27 - FUSE EXT2FS Driver

Copyright (C) 2008-2009 Alper Akcan <[email protected]>
Copyright (C) 2009 Renzo Davoli <[email protected]>
[...snip...]

I also discovered that every time I plugged the external drive into the USB port while the MacBook Pro was running, or every time the computer restarted with the external drive plugged in, a new /Volumes/Untitled* entry appeared.

Finally, I found that fuse-ext2 was writing a log file at /private/var/log/fuse-ext2_util.log. Below are excerpts of the contents. I added line wraps in long lines. Note in particular the time stamps and the path name parameters:

2014-12-17 17:06:36: fuse-ext2 script invoked with command line 
    "/System/Library/Filesystems/fuse-ext2.fs/Contents/Resources/../
    ../fuse-ext2.util" "-p" "disk2s2" "removable" "readonly" "" "" "" "" ""
.... [snip] ....
2014-12-17 17:08:24: [Mount] Entering function Mount...
2014-12-17 17:08:24: [Mount] Processing argument "/dev/disk2s2"
2014-12-17 17:08:24: [Mount] Processing argument "/Volumes/Untitled"
2014-12-17 17:08:24: [Mount] Got plain device "/dev/disk2s2"
2014-12-17 17:08:24: [Mount] Got raw device "/dev/rdisk2s2"
2014-12-17 17:08:24: [Mount] Invoking:
2014-12-17 17:08:24: [Mount]   "/usr/local/bin/fuse-ext2.wait" "/Volumes/Untitled"
    "5" "/usr/local/bin/fuse-ext2" "/dev/disk2s2" "/Volumes/Untitled"
    "-oauto_xattr,defer_permissions,local"
2014-12-17 17:08:30: [Mount] /usr/local/bin/fuse-ext2.wait returned with retval: 0
2014-12-17 17:08:30: [Mount] Output from mount operation: Mounting /dev/disk2s2
    Read-Only.
Use 'force' or 'rw+' options to enable Read-Write mode
/Library/Filesystems/fusefs.fs/Support/fusefs.kext failed to load 
    - (libkern/kext) link error; check the system/kernel logs for errors or
    try kextutil(8).
the MacFUSE file system is not available (71)
fuse-ext2: version:'0.0.7', fuse_version:'27' [main 
    (../../fuse-ext2/fuse-ext2.c:324)]
fuse-ext2: enter [do_probe (../../fuse-ext2/do_probe.c:30)]
fuse-ext2: leave [do_probe (../../fuse-ext2/do_probe.c:55)]
fuse-ext2: opts.device: /dev/disk2s2 [main (../../fuse-ext2/fuse-ext2.c:351)]
fuse-ext2: opts.mnt_point: /Volumes/Untitled [main 
    (../../fuse-ext2/fuse-ext2.c:352)]
fuse-ext2: opts.volname:  [main (../../fuse-ext2/fuse-ext2.c:353)]
fuse-ext2: opts.options: auto_xattr,defer_permissions,local [main 
    (../../fuse-ext2/fuse-ext2.c:354)]
fuse-ext2: parsed_options: auto_xattr,defer_permissions,local,allow_other,local,
    noappledouble,ro,fsname=/dev/disk2s2,fstypename=ext2,volname=disk2s2 [main
    (../../fuse-ext2/fuse-ext2.c:355)]
fuse-ext2: mounting read-only [main (../../fuse-ext2/fuse-ext2.c:371)]
Did not receive a signal within 5.000000 seconds. Exiting...
2014-12-17 17:08:30: [Mount] Executing "/usr/local/bin/fuse-ext2.daemon"
2014-12-17 17:08:30: [Mount] Exiting function mount...
2014-12-18 12:24:40: fuse-ext2 script invoked with command line 
    "/System/Library/Filesystems/fuse-ext2.fs/Contents/Resources/../
    ../fuse-ext2.util" "-p" "disk3s2" "removable" "readonly" "" "" "" "" ""
.... [snip] ....
2014-12-19 01:45:10: fuse-ext2 script invoked with command line 
    "/System/Library/Filesystems/fuse-ext2.fs/fuse-ext2.util" "-m" "-o" "nodev"
    "-o" "noowners" "-o" "nosuid" "/dev/disk2s2" "/Volumes/Untitled 2"
.... [snip] ....
2014-12-19 01:45:15: [Mount] Exiting function mount...
2014-12-20 10:56:44: fuse-ext2 script invoked with command line 
    "/System/Library/Filesystems/fuse-ext2.fs/Contents/Resources/../
    ../fuse-ext2.util" "-p" "disk2s2" "removable" "readonly" "" "" "" "" ""
.... [snip] ....
2014-12-20 10:56:45: fuse-ext2 script invoked with command line 
    "/System/Library/Filesystems/fuse-ext2.fs/fuse-ext2.util" "-m" "-o" "nodev"
    "-o" "noowners" "-o" "nosuid" "/dev/disk2s2" "/Volumes/Untitled 3"
.... [snip] ....
.... [snip] ....
2014-12-26 13:25:57: [Mount] Exiting function mount...
2014-12-26 13:41:32: fuse-ext2 script invoked with command line 
    "/System/Library/Filesystems/fuse-ext2.fs/Contents/Resources/../
    ../fuse-ext2.util" "-p" "disk2s2" "removable" "readonly" "" "" "" "" ""
.... [snip] ....
2014-12-26 13:41:32: fuse-ext2 script invoked with command line 
    "/System/Library/Filesystems/fuse-ext2.fs/fuse-ext2.util" "-m" "-o" "nodev"
    "-o" "noowners" "-o" "nosuid" "/dev/disk2s2" "/Volumes/Untitled 8"
.... [snip] ....
2014-12-26 13:41:38: [Mount] Exiting function mount...

This information was enough to give me a diagnosis, and I'm supplying that as an answer below. I included a lot of detail in the update so that search engines will index the clues, for future people with this problem.


Solution 1:

TL;DR: If you see paths like /Volumes/Untitled* piling up, trying mounting and mounting external drives and see if that correlates with more entries appearing.

I diagnosed the problem. It seems that fuse-ext2 v 0.0.7 was creating the /Volumes/Untitled* entries when the external SSD was mounted, and was not cleaning them up when the drive was dismounted. Because it failed to clean up, when fuse-ext2 was ready to create a new /Volumes/Untitled entry, it found that there was already an entry with that name, and so added an ever-increasing sequence number to the name.

I uninstalled fuse-ext2, by going to the System Preferences panel, opening the panel for fuse-ext2, and using the uninstall button there. After uninstalling fuse-ext2, I could remove and add the external SSD, and restart the computer, with no further /Volumes/Untitled* appearing.

The fact that /Volumes/Untitled* entries correlated with new entries appearing was revealing. The fact that the fuse-ext2 logs mentioned the exact path names in question, and with time stamps similar to the directory time stamps, was good confirmation.

fuse-ext version 0.0.7 dates from 2009-12-24. In the intervening five years, Mac OS has changed a lot. Yosemite, and before it Mavericks, caused a lot of problems for other software. While I don't know why exactly fuse-ext2 creates these entries and doesn't clean them up, it's not surprising that Yosemite causes problems for fuse-ext2 also.

I have deleted the /Volumes/Untitled* from the command line, with no apparent ill effects.