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Pondini Author

Level 8

38,863 points

Serious Time Machine bug on Mountain Lion

Some of us have seen a few cases of a pretty nasty problem with Time Machine backups on Mountain Lion.

In the worst cases, the backups could not be used to do a full system restore from recent backups -- they didn't appear on the selection screen that shows only "complete" backups.

Plus, they're not recognized as backups by Setup Assistant or Migration Assistant. They don't even appear on the Select the Source or Select Your System windows.

In those cases, the top-level System, Library, and (hidden) private folders weren't backed-up at all (and in at least one other, Applications as well). But all backups complete normally, and Verify Backups from the Time Machine menubar on network backups, and Verify Disk or Repair Disk via Disk Utility do not show a problem (because what's there is intact; those can't tell what's missing.)

(In addition, we've seen a few threads where backups were unexpectedly large, sometimes all of them, sometimes just some, intermittently. In at least some of those cases, one or more of those folders was getting backed-up in full. We don't know if this is really the same problem, but it sure is suspicious.)

The problem seems to be with the Time Machine preferences file being damaged somehow; the fix is easy -- do a "full reset" of Time Machine, per #A4 in Time Machine - Troubleshooting. It won't change existing backups of course, but new ones should be ok.

However, as we have no clue as to the cause yet, we need to be sure Apple knows about this, in great detail, so I'm asking for some folks who are having these problems, and are fairly comfortable with the Finder at least, and following directions to do other things you may not be so familiar with, to help us collect information and file Bug Reports with Apple before running the fix above (as that will destroy the evidence).

If you're having this problem, and your Mac is still usable, and you're interested, please post back and we'll supply instructions.

If you're having the problem and just want to run the fix, by all means do so, but please don't post back with just a "me, too" post, unless you have something significant to add -- this thread may get long and those won't really help.

But if you're having a different problem, please do not respond to this thread. Start a new one, instead. If you're not sure how to do that, please go to the main Apple Support Communities page; some Tutorials are listed at the right. They'll show you how to get started.

Posted on Jun 4, 2013 6:11 AM

48 replies

Jun 5, 2013 5:45 PM in response to Pondini

I discovered I have (it's still not corrected) this problem. I had correct backups through the week of March 3, 2013. None of the subject directories are in any of the backups since then, inckuding several hourly ones since I went through the plist reset.

Of course, the major thing that happened that week, is the release of the 10.8.3 update. But I think that has been determined as not the actual suspect, since this problem has been found much earlier.

I was, at first surprised to see three volumes in the newly reset TM plist. I think, however, they are simply the main volume and the two 'hidden' volumes; the ML Recovery and the ubiquitous "diskNs1". "N" seems to be simply the number of drives one has minus 1. I have one internal and two externals, so I have disk0s1 (the internal), disk1s1 and disk2s1 for the two external drives. One can 'see' these with Disk Utility. But the plist has them as an array of UUIDs:

<key>IncludedVolumeUUIDs</key>

<array>

</array>

They are also listed in the <key>IncludedVolumes</key> data arrays.

That confused me into thinking that TM was also backing up those two external drives! 😮

Unfortunately, I tend to install and uninstall a lot of utilities and apps. Even worse, I don't keep goodany records of what I do or when! Sorry! 😟

All I can report is that the plist has been restored but it has not made any difference in what TM is backing up... yet. I'll try another shutdown/start up and see if that does anything. 😝

Thanks for getting started on finding a solution!

Pondini Author

Level 8

38,863 points

Jun 5, 2013 5:53 PM in response to xairbusdriver

xairbusdriver wrote:

. . .

None of the subject directories are in any of the backups since then, inckuding several hourly ones since I went through the plist reset.

You're the first to report that. Could you send the preferences file to the e-mail address on the Contact page of my website? A clue may be lurking there.

I was, at first surprised to see three volumes in the newly reset TM plist. I think, however, they are simply the main volume and the two 'hidden' volumes; the ML Recovery and the ubiquitous "diskNs1". "N" seems to be simply the number of drives one has minus 1.

Yeah, that's computer talk. Zero is the first internal, others are assigned in order. But externals may change if there are more than one, and are disconnected and reconnected in a different order.

The second number is the partition number. Most drives have (at least) one hidden partiton, so what you see usually starts with 1.

Jun 5, 2013 8:17 PM in response to Pondini

Well, things ARE getting stranger!

The last two hourlies DO have the subject directories! That's fine!

However, there are also backups of two other volumes on there. One is a single volume SuperDuper backup, basically a clone of the internal ~225GB. The other is a yet to be used partition on the TM drive. That partition was to become a bootable mini-ML system, but I've yet to recreate it after doing some rearranging of the TM drive (it was running out of room and I reformatted the drive while reducing the partitions from 3 to 2).

Of course, having that extra ~225GB used is redundant and I didn't think TM was supposed to backup external drives, anyway. I must admit, however, that I either didn't know that or had forgot, because I had actually added the external partitions (all 3 of them) to the TM 'ignore' prefs before doing the plist reset procedure.

My next step is to go back and add those partitions in the TM prefs. I will make a copy of the currect plist before doing that and see if there is any change made in it. I am now wondering if those three UUIDs might actually be those two external volumes: One SD drive (single partition), the empty partition on the TM drive, and the internal drive 'single' partition (obviously, TM is 'smart' enough not to backup the Recovery partition).

I will probably need to use Terminal to see the UUIDs of all these partitions/drives. I'm betting you have the commands sitting around? Maybe even on your site. First, let me make the copy of the current plist and the one after I change the TM prefs. Then I will try to find the IDs.

BTW, there is a TM plist in my ~/Library also. I had changed a setting in Cocktail before doing the plist reset and discovered that plist had been written at the time I made the change. However, I don't want to confuse/add another wild goose trail right now! 😉

Pondini Author

Level 8

38,863 points

Jun 5, 2013 8:29 PM in response to xairbusdriver

xairbusdriver wrote:

Well, things ARE getting stranger!

The last two hourlies DO have the subject directories! That's fine!

Yay!

Of course, having that extra ~225GB used is redundant and I didn't think TM was supposed to backup external drives, anyway. I must admit, however, that I either didn't know that or had forgot, because I had actually added the external partitions (all 3 of them) to the TM 'ignore' prefs before doing the plist reset procedure.

Yes, externals are excluded by default. When you deleted the old one, they should appear automatically when you start to set up TM again.

Are these inside the Backups.backupdb folder, in the last date-stamped backup folder? There might be some in older folders, when they weren't excluded, but if they were on the list when the backup started, they shouldn't be.

I will probably need to use Terminal to see the UUIDs of all these partitions/drives.

No. I use the Info icon in Disk Utility's toolbar. (I take every opportunity to avoid Terminal. 😉)

BTW, there is a TM plist in my ~/Library also. I had changed a setting in Cocktail before doing the plist reset and discovered that plist had been written at the time I made the change. However, I don't want to confuse/add another wild goose trail right now! 😉

There might be one in ~/Library/Preferences/ByHost, but it won't have much in it, or do anything.

Jun 5, 2013 8:31 PM in response to Pondini

The three plists are "in the mail." Comparing the 'working' one (the reset one) with the one after I added the two unwanted, external partitions, indicates the principle changes were the list of UUIDs. There is only one UUID now in the includedVolumes whereas there were 3 in there before.

This seems to be a direct reversal of the published statements that Time Machine ignores other external drives. Is it possible that Time Machine itself is the culprit in this whole problem? I tend to think (although I have no proof) that plists generally get corrupted by the app itself! But you know how these things work much better than I do! 🙂 I always assumed that the app that uses the plist is the only one that writes it. Apparently, that's not always true (not counting the capability of many editors being able to write/edit the XML, of course).

Time (no pun intended, of course) to put this 'machine' in 'sleep' mode! Got a doctor appointment in the morning! S'long!

Pondini Author

Level 8

38,863 points

Jun 6, 2013 5:21 AM in response to Pondini

UPDATE:

For those who haven't devoured every word above (what fun! 😝), we're making some progress.

This does seem to be an Apple problem, which is a good thing: once we can replicate and document it reliably and easily, and file a detailed Bug Report, Apple should be able to find and fix it sooner.

In the meantime, I've added section #D10 to my Time Machine - Troubleshooting website, summarizing the symptoms, how to tell if you're affected, what we know about the problem, and of course the (possibly temporary) fix.

Stay tuned . . .

Jun 18, 2013 10:39 PM in response to Pondini

One more piece of this puzzle. Of our 4 Macs (2 iMacs and 2 MacBook Pros) only my MacBook Pro has had the problem recur. The unique things about how I use that computer are that I use it to teach classes at our local computer club which has an AppleTV hooked to our projector so we can use AirPlay to project without making any wired connections. I involves getting on our wireless network and involves accessing NAS drives for teaching material. I have reset it again and will see if hooking up to our network alone causes it to happen or if maybe it has to do with the AppleTV connection. I will report back here if I learn anything new.

Pondini Author

Level 8

38,863 points

Jun 19, 2013 5:57 AM in response to brianvegas

Great! Any clues would be really good.

You can also post a follow-up to your Bug Report.

So far, I've got evidence from at least 7 users, plus one who's filed a bug report in another way (that might get quicker attention). Another handful clearly have been bitten. I'm afraid to guess how many more have, but don't know it.

Two cases of folks covered by AppleCare, but one had already called them and they didn't seem to respond well; I tried to provide some ammunition, but don't think he followed-through. Another I tried to coach apparently hasn't called them, either, as I've heard no more.

Thanks for the update . . . I'll let you know, too, if we find anything.

ivansky

Level 2

284 points

Jun 20, 2013 12:42 AM in response to Pondini

Just wanted to touch base briefly as I think I was one of the people tagged as having similar problems - if not, please let me know. I wasn't sure if I was one of the "folks covered by AppleCare" in the previous post. My experience was backups failing due to trying to back up very large folders like /Applications and /Library even when they weren't actually modified - or at least, not modified by me. This problem has not recurred for some weeks. I'm not sure what changed. I don't have the problem where my backup is not complete. It is true that AppleCare escalated my case and never got back to me though.

Ivan

Pondini Author

Level 8

38,863 points

Jun 20, 2013 6:08 AM in response to ivansky

ivansky wrote:

Just wanted to touch base briefly as I think I was one of the people tagged as having similar problems - if not, please let me know. I wasn't sure if I was one of the "folks covered by AppleCare" in the previous post.

No, that was another user, not you.

My experience was backups failing due to trying to back up very large folders like /Applications and /Library even when they weren't actually modified - or at least, not modified by me. This problem has not recurred for some weeks. I'm not sure what changed.

Right; this particular bug causes the Applications, Library, and System folders to be skipped entirely. For some, they're skipped for a while, then included again (so cause a large backup) for a while, then skipped again, etc.

However, while chasing it, we have seen a couple more reports similar to yours. I have no idea if they're related to each other. Seems very unlikely to be a variant of the same bug, but you never know.

So, keep an eye on it; check periodically. If it happens again, and you can "catch it" while the apps/files are not being backed-up, we might be able to find a clue. If so, do a "full reset" of Time Machine, per #A4 in Time Machine - Troubleshooting, but instead of deleting the plist file, move it somewhere safe and send it to the address on my Contact page. Be sure to note your ivansky alias here, and/or a link to either this or the other thread so I can connect the two.

It is true that AppleCare escalated my case and never got back to me though.

Did they have you run something and send some data back? If so, they've probably turned it over to the software engineers.

I'm not sure when you contacted them (looks like your latest post in the other thread was June 4), but while it may take a while for them to get back to you, you can call them, give them your case number, and ask what's going on. Unless you bug them very frequently, they don't seem to mind.

The frustrating part of dealing with AppleCare is, once they figure out how to replicate the issue, and kick it to the engineers, you won't hear anything else -- not if they found the cause, or when (or even if) it will be fixed. Even if it does get fixed, they won't (or can't) tell you that!

rxbudp

Level 1

0 points

Jun 22, 2013 4:02 PM in response to Pondini

Just wanted to let you know that I am an AppleCare client and have been working with them for about a month now. I had sent them 2 separate log reports and was told that the engineers were working on the problem and expect to have it fixed with the next update. Unfortunately, that update (10.8.4) has arrived and did not fix the issue. I have not done the full reset of Time Machine since installing 10.8.4 and it was not suggested by the AppleCare advisor the last time he contacted me on June 15th. My last two emails with him are as follows:

Me to Advisor:

"I just installed the new software update 10.8.4. I didn't see anything in the details about a fix for Time Machine backup issues. Do you know if the fix was in this update? If it was, is there anything special I need to do with my Time Machine settings to get it to where my applications are being backed up? I ran a backup after the update install and my applications, library, and system files were not backed up."

Advisor to Me:

"I have still not heard anything further on the issue. I am going to ask about it again and try to get an answer for you. As far as I know there was nothing in the update to correct the issue but I will check on that as well."

I am running TimeMachine on an iMac and backing up to a 2 T segate drive. Let me know if there is some way I can help get this issue resolved. I will certainly post any updated information I might receive from the AppleCare advisor for my case.

Pondini Author

Level 8

38,863 points

Jun 22, 2013 5:50 PM in response to rxbudp

Ah, good to hear somebody's got their attention. 🙂

Did they have you run any diagnostic reports and send the results back?

If you want to contact them again, I can give you some ammunition:

We still don't know the cause, but the effect can be seen in the /Library/Preferences/com.apple.TimeMachine.plist file. It has the top-level files listed in the ExcludeByPath section (which isn't something you can do, and isn't shown on the TM Preferences window).

That's a binary file, so you can't really make sense of it with a text editor; you need a special plist editor, and I don't know of any free ones. If you'd like to send me that file (at the address on my Contact page), I'll display it, screen-print the result, and send it back. (If you do that, please identify yourself by your rxbudp name here, so I'm sure it's you). If you don't mind, also give me the Case Number -- we can have others include it with their reports.

Then you can send the screenshot and the actual file to AppleCare and it might at least give them a clue.

You might also refer them to this thread, and/or my page at #D10 in http://pondini.org/TM/Troubleshooting.html, and/or tell them I have evidence (plist copies) from 7 other users, and would be GLAD to help. I can't report it as a bug myself, though, as I've not figured out how to reproduce it.

The fix on my web page will fix it, at least temporarily, but will also replace the file in question, destroying the evidence, so if you don't mind, don't run it until you've talked to AppleCare again.

Thanks!

Jun 23, 2013 12:41 AM in response to Pondini

To display a binary prefs file, copy it somewhere:

$ cp /Library/Preferences/com.apple.TimeMachine.plist /tmp

$ cd /tmp

convert to XML:

$ plutil -convert xml1 com.apple.TimeMachine.plist

then you can use it as a text file, with your favourite utility:

$ more com.apple.TimeMachine.plist

$ open -a textedit com.apple.TimeMachine.plist

Jun 23, 2013 1:22 AM in response to Pondini

I am in the 'happens occasionally' camp. The last occurrence, yesterday, was directly after TM performed one of its periodic verifications. I had also just installed MacTex 2013...

Pondini Author

Level 8

38,863 points

Jun 23, 2013 5:38 AM in response to fivenotrump

fivenotrump wrote:

I am in the 'happens occasionally' camp. The last occurrence, yesterday, was directly after TM performed one of its periodic verifications. I had also just installed MacTex 2013...

Ah, that may be a clue. 🙂

Have you already run the fix? If not, I'd like to enlist your help if possible:

If you're covered by AppleCare, reporting it to them is probably the best way to get quick attention. If so, let me know, and I'll try to provide some ammunition, as in my earlier reply to rxbudp.

If you're not covered by AppleCare, filing a Bug Report should help. I know of at least one that's been filed with them so far, and I can provide the number so you can cross-reference. In addition, you could run the TMdiagnostics and attach the results.

Let me know . . .

p.s: I clicked This solved my question in error, instead of Go to the message in the e-mail reply to your other post . . . I've asked the Host to reverse it, but I don't know if they can.

Message was edited by: Pondini

Serious Time Machine bug on Mountain Lion