.Trashes, .fseventsd, and .Spotlight-V100
Merely plugging a removable drive into a mac (when it has write access) makes OS/X think it can take the liberty to write a lot of hidden garbage onto that disk. If you want to stop this from happening, you have to put some special files on that disk before you plug it in.
To stop OS/X from doing Spotlight indexing, you need a file called .metadata_never_index in the root directory of the removable drive.
To stop OS/X from making a .Trashes directory, you need to make your own file that *isn’t* a directory and call it .Trashes
To keep it from doing logging of filesystem events on the drive, you need to make a directory called .fseventsd and inside that folder put a single file named no_log
The contents of these files don’t matter, so you can make them empty files using touch. Even better, you could make it a text file with a link to this post, so that you (or someone else) wandering across the files will know what they’re for.
Apple’s choice to do this is incredibly self-serving and shameful. At bare minimum, hidden files and features like these should be off by default for any non-mac-only filesystem formats. They should only be enabled when the user has been made aware of them.
December 2nd, 2009 at 8:33 pm
I’d like to share with you the story of a botched backup software installation, a lost partition table/boot sector, untold hours spend relearning enough about hard disks, partition tables, FAT filesystems, etc., to locate the start of the second partition (which happened to be close on disk to where an older partition used to live).
Partition table finally reconstructed, I plug it into my Mac. Having clicked on the first file it’s clear there is something still terribly wrong with the drive - it seems I’ve created the partition table to point at one of the old ‘nearby’ filesystems, rather than the most recent one.
Ordinarily, simply updating the start of partition +3mb or so would have been all required, but OS X had kindly created all the files you mentioned above - clobbering to death the second partition image.
Never, ever, ever, use OS X for recovery. These are toy computers for toy people, that do toy things when you least expect it.. like writing to a f**king disk without asking. Lesson learned.
December 5th, 2009 at 12:32 am
Actually, many unix systems will write to a mounted disk automatically, unless you mount the fs with the -noatime flag. I think if you mount the disk read/write, that’s giving the OS permission to write to the disk. If you don’t want it to do that (e.g. Because the fs integrity is damaged) the you need to be sure to mount it read only.
Apple’s focus is rightly on providing the best user experience to the non-technical user. People trying to rescue hosed filesystems or avoid harmless dot-files are a special niche, and a secondary concern at best.
December 11th, 2009 at 2:15 pm
@Jeremy:
It is certainly true that most unix-like operating systems AND WINDOWS will automatically write to a file system. However, file system recovery is a basic operation common to ALL operating systems. If the default behavior of Mac OSX prevents recovery, then it is simply the wrong action.
It really is not hard to wait and see whether the user is trying to perform actions that require those added files to be there.
As a Linux user, I am often called upon to recover data for Windows users. Mac users probably get just as many requests. If the OS trashes the drive before one can perform the recovery, then the above comments about not being acceptable for serious usage are true.
January 5th, 2010 at 11:16 pm
Awesome! Thanks for this post. I have no proof, but I suspect these were screwing up my RAID. Incidentally, I have my RAID drive added to be excluded from both Time Machine and Spotlight, yet these directories are still created and contain loads of data.
January 11th, 2010 at 2:01 am
Folks connecting external drives to a Mac should mount them read-only if they don’t want them written to (just like a savvy user would ‘mount -r’ or ‘mount -o ro’ under Linux). Here’s a prefpane (”ReadOnlyMounter”) that helps with that:
http://homepage3.nifty.com/extant/MacOSXsoft/MacOSXsoft.html
I agree, the use of .Cruftiness to tell Spotlight and fseventsd and Finder not to drop crap on my drives is irritating. I use these to help with that:
http://www.zeroonetwenty.com/blueharvest/
http://myhowto.org/mac-os-x/52-disabling-spotlight-in-os-x-leopard-for-the-removable-drives/
To be honest, I’d rather live with this stuff than with Windows Vista constantly rearranging my desktop icons and resetting my folder views on its whim, because it thinks one file is a photograph, so therefore the whole folder must contain photos and i must want to view them as tiles, even though every other bleeding time i viewed the folder i viewed it as a Detailed List. At least Apple makes it possible to turn it off….