Apple’s Time Machine Bug May Ignore Drives

We’ve talked about backing up your data quite extensively here on the OWC Blog. We’ve talked about different backup strategies. We’ve discussed mirrored RAID devices like the NewerTech Guardian MAXimus and how they can fit into your backup scheme. We’ve touched on how you need to keep an eye on your backup software to make sure it’s doing what it’s supposed to.

It’s in the vein of that last one that we bring you this little tidbit from Lloyd Chambers of MacPerformanceGuide. It seems that Lloyd has found a bug in Time Machine that may cause your Mac to ignore drives under some circumstances. We highly recommend checking out the full article out for the complete analysis of the issue.

The lesson to be learned from all this is that when it comes to backups, the more the merrier. While some backup is better than nothing, it’s always safest to have multiple backup methods in place at once. While I do use Time Machine here on my work machine, it is mainly for retrieval of accidentally-deleted files (I use this a lot more often than I care to admit) and to supplement my daily cloning of my drives using Carbon Copy Cloner. This current method has worked for me for several years now, and has saved me from at least one major drive crash, so I’d say it’s functional. I’d also rotate those clones out at least weekly, but that’s not a practical solution at this time.

So what are you using for backup?


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  • Hi, I have been looking at setting up my mac as a Fusion Drive setup, with the OWC Mercury and Data Doubler in my MBP. While waiting for it to come, there are some questions that bugs me, leaving me unable to decide if I should do a Fusion Drive or Separate my bulk data. Here are my Questions.

    1) If I were to set up a Fusion Drive, will Time Machine will backup every file in the OS (SSD and HD) as one volume, hence to restore it to a single drive would be no problem?

    2) If i were to Use an SSD as my boot disk, manually linking my user data to my Hard Disk, would Time Machine back up the data in my HDD as though my System is on one drive?

    Thanks in advance!


  • I am being given a new Imac 27″ for Christmas and am interested in getting a reliable backup system for a home office situation.
    Can you please advise the best solution.

    Ps I am not technically minded!

  • Several layers:

    1. My writing files (small, frequently modified) are in a Dropbox folder, so they’re backed up in real time, offsite.
    2. My internal drive and external media drive are backed up via Time Machine hourly to another external.
    3. I clone these two drives once a month with Carbon Copy Cloner, and keep the clones at an offsite location. The clones are encrypted using core encryption built into OS X.

    Between Dropbox and Time Machine, I’m covered for accidental deletions, modifications or corruption of everything. And the offsite clones are my “worst scenario” fall-backs. Starting from those (and with Dropbox bridging the gap), I could recover everything really important in the event of a catastrophe or theft at my apartment.

  • Backup outside your location is crucial for important filles. I use time machine on my local network and Backblaze for cloud backup

  • I use rsync to backup files to an encrypted sparse image on an external drive. I have a number of these drives, all with sparse images of the same title encrypted with the same password (which is saved in my Finder so I don’t have to remember it). Once a month I shuffle the drives between home and work, ensuring that no two drives are in the same place at the same. Rsync has no problem with the differing drives, correctly backing up whatever has changed since the last time that drive was mounted.

    Each sparse image is much larger than the drive it resides on, allowing me to easily copy the image to a larger drive if need be without having to resize the image (or copy the data to a new image).

    I quite like the idea of encrypted backup. If someone steals a drive (onsite or off) my only loss is a cheap external drive.

    For versioning backup I rely on Dropbox backing up my working directory. The way Dropbox can act as a poor-man’s versioning system has saved my bacon a couple of times.

  • We run a Mac Mini Server running a RAID 1 with the two internal drives for hardware redundancy. I’ve had to replace each of the factory drives so far due to failure. The RAID saved our bacon in those instances.

    We then run nightly incremental backups using Carbon Copy Cloner to an external drive in a Newer Technology Voyager drive dock, alternating drives every week or two. This gives us a way to go back and grab deleted files, and store backup data off site.

    I initially found running Time Machine on the server to be unreliable. And if I don’t trust it, I’m not going to use it for company critical data. However we do back up our Mac Pro workstations over Time Machine to a spare internal drive. This is more for “oops, did I delete that?” or if the Mac Pro drive fails, we can get a station back up quickly.

    It’s a simple, inexpensive solution that covers us in just about any event.

  • I have also used Time Machine for some time. I have not noticed any issues at all except as what MaX noted. I have also had to infrequently unmount disks and then remount them. This kind of behavior has not happenend in my case.

  • My storage is initially backed up in the form of RAID 5. I have a 4x2TB setup in my Mercury QX2. I have another 4x2TB RAID 5 setup that I use as my Time Machine backup. It may seem like overkill, but there’s a lot of irreplaceable data as well as painfully time-consuming-to-replace digital media, and this setup gives me peace of mind for my onsite backup needs.

  • Which version of Time Machine and OS X has such bug?

    I have been using Time Machine for years and it has worked always fine except when the free disk space is low (the solution was to make a fresh backup from scratch).