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Weird Time Machine backup problem
Posted by: PeterB
Date: April 09, 2022 04:58PM
Saw an odd message this morning on my Mac Pro 5,1 running Mojave, about how my Time Machine backup had changed and that someone might be trying to steal my data (!)... I've NEVER seen this error before. The dialog box had the options either to use the backup or not to, with the "not to" as the default option.

So just to be safe, I restarted the machine, and ran Disk Utility on the Time Machine backup ... DU says it's fine. Then I try to set Time Machine to use the drive as a backup, and it is able to "see" the drive, but is unable to see that there are any backups on it, when in fact it has weeks (maybe months) of backups on it.

Anyone ever seen this before, and know how to get it to recognize all the backups again? I'd rather not reformat the drive-- I would like access to those backups.

TiA




Freya says, 'Hello from NOLA, baby!' (Laissez bon temps rouler!)
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Re: Weird Time Machine backup problem
Posted by: Tiangou
Date: April 09, 2022 06:12PM
I see this all the time with network TM backups. The target disk image becomes corrupt and after a few start-over messages, sometimes a "the identity of disk xyz has changed..." message will pop up.

At that point, I trash the old disk image and start a fresh backup, which triggers ANOTHER "the identity of disk xyz has changed..." message.

I have not seen the same type of problem with local backups. I'd be very wary of a drive that triggers that sort of error. Have you run a SMART check on it yet?



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Re: Weird Time Machine backup problem
Posted by: PeterB
Date: April 09, 2022 08:21PM
Quote
Tiangou
I see this all the time with network TM backups. The target disk image becomes corrupt and after a few start-over messages, sometimes a "the identity of disk xyz has changed..." message will pop up.

At that point, I trash the old disk image and start a fresh backup, which triggers ANOTHER "the identity of disk xyz has changed..." message.

I have not seen the same type of problem with local backups. I'd be very wary of a drive that triggers that sort of error. Have you run a SMART check on it yet?

Says SMART is not supported on this drive... it's a 10TB Firewire drive.

But... I think I solved the problem on my own. Found this great, but very old, website that is no longer maintained... so that I had to look at the web archive:

[web.archive.org]

... crazy, but yes, apparently you have to do a backup in order for TM to "see" the old backups on the drive.




Freya says, 'Hello from NOLA, baby!' (Laissez bon temps rouler!)



Edited 1 time(s). Last edit at 04/10/2022 09:01AM by PeterB.
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Re: Weird Time Machine backup problem
Posted by: Tiangou
Date: April 09, 2022 08:49PM
Interesting.

I haven't encountered that one before.

Thanks for posting the solution!



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Re: Weird Time Machine backup problem
Posted by: PeterB
Date: April 10, 2022 09:05AM
Quote
Tiangou
Interesting.

I haven't encountered that one before.

Thanks for posting the solution!

That website ... it's amazing, and a real shame that it's no longer up, since he has just about every possible problem with TM listed-- as well as solutions to each.

I'm not sure why this drive doesn't support SMART ... it's a 10TB Enterprise-level drive, in a Firewire OWC enclosure to which I added fans for cooling (since the drive puts out a good amount of heat). Other than it making a fair bit of noise (now drowned out by the fans), it's worked very well thus far.




Freya says, 'Hello from NOLA, baby!' (Laissez bon temps rouler!)
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Re: Weird Time Machine backup problem
Posted by: Tiangou
Date: April 10, 2022 09:59AM
Quote
PeterB
I'm not sure why this drive doesn't support SMART ... it's a 10TB Enterprise-level drive, in a Firewire OWC enclosure...

Have you installed the SMART SAT driver?



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Re: Weird Time Machine backup problem
Posted by: PeterB
Date: April 10, 2022 10:30AM
Quote
Tiangou
Quote
PeterB
I'm not sure why this drive doesn't support SMART ... it's a 10TB Enterprise-level drive, in a Firewire OWC enclosure...

Have you installed the SMART SAT driver?

Don't recall... I remember trying SMART Utility, but discovering that it was giving all sorts of misleading information about the SMART statuses of drives. If I launch that app now, it doesn't even show the drive in the list of current drives. I also have a version of Disk Drill that allows to monitor SMART status, and it shows the drive as an external RAID.




Freya says, 'Hello from NOLA, baby!' (Laissez bon temps rouler!)



Edited 1 time(s). Last edit at 04/10/2022 10:59AM by PeterB.
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Re: Weird Time Machine backup problem
Posted by: Tiangou
Date: April 10, 2022 10:35AM
Quote
PeterB
Quote
Tiangou
Quote
PeterB
I'm not sure why this drive doesn't support SMART ... it's a 10TB Enterprise-level drive, in a Firewire OWC enclosure...

Have you installed the SMART SAT driver?

Don't recall... I remember trying SMART Utility, but discovering that it was giving all sorts of misleading information about the SMART statuses of drives. If I launch that app now, it doesn't even show the drive in the list of current drives.

I don't know what you mean about "misleading."

...Anyway, if you want to check SMART status on externals, update to the latest version of the app and use it to install the SAT driver. Reboot and *most* externals should appear in the list. (May appear as "unsupported" if the bridge doesn't pass SMART info.)



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Re: Weird Time Machine backup problem
Posted by: PeterB
Date: April 10, 2022 11:01AM
Quote
Tiangou
Quote
PeterB
Quote
Tiangou
Quote
PeterB
I'm not sure why this drive doesn't support SMART ... it's a 10TB Enterprise-level drive, in a Firewire OWC enclosure...

Have you installed the SMART SAT driver?

Don't recall... I remember trying SMART Utility, but discovering that it was giving all sorts of misleading information about the SMART statuses of drives. If I launch that app now, it doesn't even show the drive in the list of current drives.

I don't know what you mean about "misleading."

...Anyway, if you want to check SMART status on externals, update to the latest version of the app and use it to install the SAT driver. Reboot and *most* externals should appear in the list. (May appear as "unsupported" if the bridge doesn't pass SMART info.)

Showing SMART status as being failing when other apps all say the drives are fine.

I edited my post above, I am using the latest version and the drive is still not shown in the list. It's possible it doesn't pass SMART info, as you've mentioned.




Freya says, 'Hello from NOLA, baby!' (Laissez bon temps rouler!)
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Re: Weird Time Machine backup problem
Posted by: Tiangou
Date: April 10, 2022 12:14PM
If it's a yellow "fail," you have issues that may compromise the function of the drive, get your backups in order. If it's red, it's probably too late to back up everything reliably. If it's black, you're lucky it hasn't taken hostages on the way out.



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Re: Weird Time Machine backup problem
Posted by: PeterB
Date: April 10, 2022 02:45PM
Quote
Tiangou
If it's a yellow "fail," you have issues that may compromise the function of the drive, get your backups in order. If it's red, it's probably too late to back up everything reliably. If it's black, you're lucky it hasn't taken hostages on the way out.

Yellow, but when I asked you about these errors (I think we communicated by PM about them), you told me that considering that two or three other apps were showing the drives as being fine, and that the errors were relatively few / minimal, that the drives are probably OK.




Freya says, 'Hello from NOLA, baby!' (Laissez bon temps rouler!)
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Re: Weird Time Machine backup problem
Posted by: Tiangou
Date: April 10, 2022 05:06PM
Quote
PeterB
Yellow, but when I asked you about these errors (I think we communicated by PM about them), you told me that considering that two or three other apps were showing the drives as being fine, and that the errors were relatively few / minimal, that the drives are probably OK.

Not sure which conversation you're referring to... I did a quick search and see one from 2015... I don't think this is the same drive.

In the case of a yellow "FAILING" notification you need to look at the types of errors and the number of errors to judge how bad a SMART report is.

A few remapped sectors and a couple of DMA errors are a reminder to bring your backups up to date.

A lot are a reminder that life is fleeting.



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Re: Weird Time Machine backup problem
Posted by: PeterB
Date: April 10, 2022 08:02PM
Quote
Tiangou
Quote
PeterB
Yellow, but when I asked you about these errors (I think we communicated by PM about them), you told me that considering that two or three other apps were showing the drives as being fine, and that the errors were relatively few / minimal, that the drives are probably OK.

Not sure which conversation you're referring to... I did a quick search and see one from 2015... I don't think this is the same drive.

In the case of a yellow "FAILING" notification you need to look at the types of errors and the number of errors to judge how bad a SMART report is.

A few remapped sectors and a couple of DMA errors are a reminder to bring your backups up to date.

A lot are a reminder that life is fleeting.

It may have been another MRFer that I discussed it with. My recollection is that there are only a few reallocated/removed bad sectors, as you might expect for any drive. Also, as I mentioned, other SMART utilities are reporting NO problems with these drives.




Freya says, 'Hello from NOLA, baby!' (Laissez bon temps rouler!)
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Re: Weird Time Machine backup problem
Posted by: Tiangou
Date: April 10, 2022 08:30PM
Quote
PeterB
My recollection is that there are only a few reallocated/removed bad sectors, as you might expect for any drive. Also, as I mentioned, other SMART utilities are reporting NO problems with these drives.

It's worth double-checking.

First, once they appear, bad sectors and read/write errors tend to accumulate over time. If the number grows, it's a sign that the drive is on its last legs.

Second, different SMART utilities use different thresholds for determining what a "fail" state is. The Apple Disk Utility, for example, doesn't mark a drive as failing until there are so many errors that the data's probably not recoverable.



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Re: Weird Time Machine backup problem
Posted by: PeterB
Date: April 10, 2022 09:00PM
Quote
Tiangou
Quote
PeterB
My recollection is that there are only a few reallocated/removed bad sectors, as you might expect for any drive. Also, as I mentioned, other SMART utilities are reporting NO problems with these drives.

It's worth double-checking.

First, once they appear, bad sectors and read/write errors tend to accumulate over time. If the number grows, it's a sign that the drive is on its last legs.

Second, different SMART utilities use different thresholds for determining what a "fail" state is. The Apple Disk Utility, for example, doesn't mark a drive as failing until there are so many errors that the data's probably not recoverable.

SMART Utility is the only one of four different utilities that says the drives are failing. Of three drives, two have one each pending and removed bad sectors, one has one reallocated bad sector, and one has 4 pending bad sectors and two removed bad sectors. Of these drives, one is backup for another, so if one of them goes, I will still have the other. The one with the most bad sectors is being backed up by the TM backup, but I can make a complete backup of that one too. None of these drives has apparently hit the "thresholds".




Freya says, 'Hello from NOLA, baby!' (Laissez bon temps rouler!)
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Re: Weird Time Machine backup problem
Posted by: Tiangou
Date: April 10, 2022 09:51PM
It failed the SMART check. It's "failing." But it's a "yellow alert" fail.

Yeah, you can probably go awhile with so few bad sectors.

Glad you have backups.



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