External drive doesn't completely back up in Time Machine

Lariat · Mar 28, 2015

I have a LaCie external hard drive that is my Time Machine backup destination. It's plenty big enough (4TB) to hold the contents of my 3TB iMac, since I only have about 750GB of files so far on the iMac.

The problem is that when I go into the Time Machine to see if a file is there, it often isn't. Even though the file is still on my iMac's internal hard drive, it doesn't show up in a Time Machine backup in some cases until I go way, way back. And I never know how far back I need to go to find it.

My first question: Is this normal? Shouldn't every backup done by the LaCie include everything until it's full? (Currently 2.6TB of storage is still available on the LaCie.)

My second question: If this is normal operation, then how do I know how far back I need to go in Time Machine to find a particular file? It could be on any day's backup between now and when I got the LaCie last July.

The internal hard drive on my iMac hasn't failed--but I want the security of knowing I'll be able to find a file if it ever does.

Thanks.

chscag · Mar 28, 2015

Read through the following Apple KB article to see if it helps you to understand how to restore individual files from a Time Machine backup. The article is also a good overview on how Time Machine works.

Many of us recommend a second backup method in addition to Time Machine. A cloned backup is not only bootable (Time Machine backups are not) but they're much easier to use for restoring individual files especially mail. Carbon Copy Cloner or SuperDuper are two such apps that will make a clone of your hard drive.

Lariat · Mar 28, 2015

Thanks, chscag. I will try that.

As for my first question: Is it normal that when I go back in Time Machine to a particular day, I find that a folder contains far fewer files than it really did on that day? Is this a deliberate strategy on the part of Time Machine to take up less disk space on the external drive? (Because it knows that as long as it exists somewhere on some day's folder, I'll find it doing a search on the finder?)

2xhorn · Mar 28, 2015

Time machine does incremental backups, meaning only that that has changed since the last backup. So if you have an old and unchanged file it may not have been backed up on X date, but will be in the original backup. Also explains why folders on X date backup show fewer than the contents of the entire folder, it only backed up what had changed.

Lariat · Mar 28, 2015

Thanks, 2xhorn.

Slydude · Mar 28, 2015

@2xhorn If I am understanding you correctly this is not exactly how Time Machine behaves. If you look at a folder that Time Machine has backed up it should contain as many files/folders as it did at the time the backup was made.

I just looked at my Time Machine backup of a certain folder. The original folder contains 162 items. So does the current Time Machine backup despite the fact that only a handful have been changed in the last several days.

It's true that Time Machine only copies files that have been changed but it doesn't omit unchanged files from what you see in the backup. Time machine creates new copies of files that have changed since the last backup. For unchanged files it creates a pointer back to the unchanged file.

@Lariat It seems that something odd is happening here but I haven't pieced together what it is yet.

2xhorn · Mar 28, 2015

Ah well perhaps you're right. I actually have never restored anything from a Time Machine backup.

harryb2448 · Mar 28, 2015

Not perhaps. Sly is right.

Lariat · Mar 28, 2015

Right, Slydude. If I go into the Time Machine "Universe," and look at "Now," all the files in a particular folder that should be there are there. But if I go even to the most recent backup (which is less than an hour ago), several are missing.

Slydude · Mar 28, 2015

Until we figure out what's happening this document might help with a faster way of finding the files you are looking for. Skip to the sections on restoring files. Specifically the section on using the Finder window portion of the Time Machine interface.

A couple of questions occur to me that might help clear up this issue:

1. Have you used Disk Utility to verify (and if necessary) repair the drive? I'm not so much worried about verifying/repairing permissions just the directory structure of the drive.

2. Is the backup drive connected directly to the Mac or connected through a network device such as Airport or Time Capsule? Time Machine can use drives connected to a network device but you may have to add an extra step to the verification process.

Lariat · Mar 28, 2015

Sly, on your suggestion, I just used Disk Utility to verify the LaCie drive. Even though it ended up saying everything was OK, I decided to repair it anyway! The result of that process was still "appears to be OK," but this time, a new line was added: "Updating boot support partitions for the volume as required."

Maybe that will fix the problem. I'll report back.

Slydude · Mar 28, 2015

If my understanding of that command is correct it shouldn't affect things since you are not booting from that drive.

2xhorn · Mar 28, 2015

Here's an oddity. I use time machine on a USB drive. I plug it in every 2-3 days and let it run. I did one last night.

Previously, I had noted on About This Mac/Storage that there was a pretty large segment (~4GB) of the drive devoted to "backups." When I would "Enter Time Machine" I would get a full finder window and be able to examine what I believed was a temporary backup that just hadnt been finally updated and moved to the USB drive.

When I went to look at time machine in response to this thread, it opened the finder window and then said the backup drive couldn't be found, blah blah blah. I did not bother to fetch the drive and plug it in. I also note that on About this mac/storage, "backups" is down to 4MB. In other words, time machine behaved like there was no temporary backup that it could access and the storage graph seems to confirm that backups was an order of magnitude smaller than usual.

I know that time machine does different kinds of incremental backups if operating full time, e.g. dailies, weeklies, etc.

Does the above mean that time machine did a more "complete" backup last night than it had been doing of late?

Another note, when I use Omni Disk Sweeper, it used to show some sort of "backup" partition or drive and now it doesnt.

2xhorn · Mar 28, 2015

Also, goofing around with Time Machine, I reorganized a folder on March 18. Mostly moving existing files into existing folders, creating a couple of new folders and a couple of new documents. I have since added to the new folders.

I have let Time Machine run since then on March 21, 24, 25, and 27. However the folder shows in its pre-March 18 state on all but "Now." That is, it is in it's disorganized state and missing the 2-3 new folders and their contents. What the ****?

Looking around, there are quite a few folders that weren't backed up on the dates in question, despite having changed. What the **** is going on?

Rod · Mar 29, 2015

Lariat, can I ask what may be a stupid question? You say, "The problem is that when I go into the Time Machine to see if a file is there, it often isn't. Even though the file is still on my iMac's internal hard drive, it doesn't show up in a Time Machine backup in some cases until I go way, way back. And I never know how far back I need to go to find it."
The reason I ask is because I once had a client who referred to her TM backup but was not using the TM interface at all. She had not "Entered Time Machine" but was looking at the files in her external HD (called Time Machine) via a finder window. It took a while to realise that she had no idea that there was a TM Interface. Obviously the contents of the TM backup drive are intended to be viewed through the interface, they are a little difficult to navigate in a finder window because they are not designed to be viewed that way.
So please humour an old man and confirm that you are viewing the TM application interface.
If so you have a very unusual problem. :Confused:

Rod · Mar 29, 2015

Sorry Lariat, I just noted your reference to the time machine "universe" so I guess that answers my question.

Rod · Mar 29, 2015

I can confirm what everyone else has said, your TM backups are not behaving like mine. Even though I did not have my TM backup plugged in last night now that I have I can see the hourly changes created by incremental snapshots of two folders, all other content remains complete and the same.
So even though the external drive tests ok and providing you are sure you will not need any recently trashed files or changes I would be tempted to erase and reformat the external and do a new full TM backup. After all If you cant rely on it completely it's worse than useless.
Keep an eye on it or create a second one if you are uncertain, it would be $100.00 well spent, especially if you are not using cloud type backups. A Carbon Copy or SuperDuper clone as well as TM would not be overkill, I have both. The Carbon Copy Cloner copy is bootable and the files are easy to navigate with the finder plus you get options on what, when and how often to store data.
I have just finished replying to a post where an OP waited till their HD effectively crashed ignoring error messages before trying to back up their 500Gb + of iPhoto files and guess what? No TM backup. At least you have one.

Lariat · Mar 29, 2015

No problem with the question, Rod. Anything that gets me to a solution is something I welcome.

By "viewing the TM application interface," I assume you mean going to the Time Machine icon in the upper right of my desktop, dragging down to Enter Time Machine, and having my display change to the "starry Time Machine universe" with a folder at the center of it. If that's what you mean, then yes, I'm doing that. (Although I have also done the thing you describe your client as having done.)

When in that TM application, if I even go back from Now to the very most recent backup, files that are in the Now folder are missing from the backup.

One thing I'm wondering: Is the problem likely to be with my LaCie external hard drive, or is it with the Time Machine application in my iMac? If it's the LaCie, then certain solutions present themselves to me: 1) erasing the entire contents of the LaCie and starting over; 2) unmounting the LaCie, physically disconnecting it from the iMac, unplugging it from power, then reconnecting it to see if that does the trick; 3) buying a different external hard drive from a different manufacturer and seeing if that works better.

But if the problem is actually in my iMac (a relatively new one, purchased last July), then none of those actions will make a difference and may be risky and/or expensive to try for no solution.

Rod · Mar 29, 2015

Lariat said:
No problem with the question, Rod. Anything that gets me to a solution is something I welcome.

By "viewing the TM application interface," I assume you mean going to the Time Machine icon in the upper right of my desktop, dragging down to Enter Time Machine, and having my display change to the "starry Time Machine universe" with a folder at the center of it. If that's what you mean, then yes, I'm doing that. (Although I have also done the thing you describe your client as having done.)

When in that TM application, if I even go back from Now to the very most recent backup, files that are in the Now folder are missing from the backup.

One thing I'm wondering: Is the problem likely to be with my LaCie external hard drive, or is it with the Time Machine application in my iMac? If it's the LaCie, then certain solutions present themselves to me: 1) erasing the entire contents of the LaCie and starting over; 2) unmounting the LaCie, physically disconnecting it from the iMac, unplugging it from power, then reconnecting it to see if that does the trick; 3) buying a different external hard drive from a different manufacturer and seeing if that works better.

But if the problem is actually in my iMac (a relatively new one, purchased last July), then none of those actions will make a difference and may be risky and/or expensive to try for no solution.

Somehow I doubt it's the mac but you could do a check on the HD and permissions just in case.
Really it's a matter of elimination.
If you buy a new drive it will get used eventually even if only for a clone.
If it works ok with TM then your LaCie is at fault and of not its your iMac.
I would do as you suggest and power it down and retry first. These things do die occasionally and Disk Utility is not the best app for picking up bad blocks.

Lariat · Mar 31, 2015

Checking in to say the problem is solved. And the problem was solved by--switching to a different external hard drive. The problem was the 4TB LaCie, obviously.

What caused the problem with the LaCie, I have no idea. It seems to work fine as a storage device. When I drag files to it, it doesn't lose them. (At least not yet.) But it doesn't seem to work very well with Time Machine.

The drive that does work fine with Time Machine--preserving all my files in every update--is a 3TB G-Force that I was using for other things. Ideally this G-Force would be 4TB or larger (my internal hard drive is 3TB), but it will do for now. (I have a little less than 1TB of files on the internal drive.)

External drive doesn't completely back up in Time Machine

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