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PostPosted: Mon Aug 27, 2018 6:45 am 
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This was a shocking way to start a week. TriBackup performs several backup tasks every hour. At 7:03 this morning, all backups ran successfully. At 8:03, even though not a single thing was changed (at least by me), 2,891 files could not be written from Audio 1 to the destination (Audio 2). Disk First Aid was unable to unmount Audio 2, claiming it was in use. Even after booting into Recovery and trying again. My only choice then, I thought, was to run Disk Warrior to rebuild the directory. It was successful, and it recovered a lot of files, but I think it'll be easier for me to copy back to that volume the entire contents of the previous successful backup, which resides on a third drive.

Any thoughts on what might've caused a failure like this?

Also, when restoring Audio 2 from its backup, would it be wise to erase and reformat first?

Thanks.

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PostPosted: Mon Aug 27, 2018 7:51 am 
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How full was the drive?

Is Spotlight disabled on Audio 2?

Reformatting Audio 2 would help greatly with file fragmentation.


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PostPosted: Mon Aug 27, 2018 10:05 am 
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Audio 2 had, at best guess, around 500 GB (perhaps a bit less)free, and Spotlight was disabled. I don't think the drive was badly fragmented, either. I seem to recall running iDefrag on it within the last year.

EDIT: But HERE's something weird: after having successfully rebuilt the directory, I'm now running Disk First Aid. If I select the volume on Audio 2, DFA says it's fine. But, if I select the drive itself, DFA says it "found some corruption that needs to be repaired. To repair the startup volume, run First Aid from Recovery." Audio 2 is certainly not a startup drive. Is DFA confused somehow? Will a reformat fix this?

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PostPosted: Mon Aug 27, 2018 10:30 am 
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I'm not 100% positive, but that sounds like the Partition Map is bad & reformat should clear up that problem.


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PostPosted: Mon Aug 27, 2018 11:06 am 
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Many thanks, BD!

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PostPosted: Mon Aug 27, 2018 11:31 am 
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Y'know, now that I think about it, here's another oddity.

The TriBackup error list showed the last files to be handled during that fateful backup. But, there would've been no reason to do anything with those files because, as I said earlier, nothing had changed on the source or destination volumes between the successful backup at 7:03 and the stinker at 8:03. I was sitting here eating breakfast while poking around online during that time.

Do you know of anything that would cause TriBackup to believe files had changed when they had not? And I also wonder what would've caused a partition to become corrupt so suddenly. If these things happened once, they could happen again.

How bizarre.

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PostPosted: Mon Aug 27, 2018 11:32 am 
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I try to treat DiskWarrior as a last-gasp way to recover data, it's not guaranteed to return a screwed up disk to a perfect state. Any time you have to run DiskWarrior to regain access a disk you should get your data off then wipe it all out and create the partition map fresh. I've learned the hard way not to trust the disk w/o a wipe.

As for how it got that way... did you ever disconnect the disk uncleanly? Power outage? Accidental power cord tug? When a disk isn't unmounted cleanly it can get corrupt and Apple isn't particularly good about alerting you to the damage. If anything it seems like they're going to greater lengths to hide the growing problem until it becomes a catastrophe and can't be ignored.


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PostPosted: Mon Aug 27, 2018 11:51 am 
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Thanks, MB, for the tip on Disk Warrior. Much appreciated. And it's certainly possible that, at some point, the disk had become disconnected improperly. My standard practice following something like that is to run Disk First Aid. And, when I do, I check both drives and volumes. I also run DFA every so often anyway, even if nothing indicates a problem. And I seem to remember doing so pretty recently; within the last month or so and, at that time, both the drive and volume turned up OK, apparently. But, to my knowledge, nothing out of the ordinary happened between 7:03 and 8:03 this morning.

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PostPosted: Mon Aug 27, 2018 11:53 am 
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Yeah, that doesn't surprise me. It falls under the category of Apple going to greater lengths to hide problems from the user. They've got a mythology to defend I guess.


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PostPosted: Mon Aug 27, 2018 12:06 pm 
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Just so I understand: when you say "Apple," do you mean that their Disk First Aid (or the OS) is not correctly reporting issues? I ask because the drive in question is an external (USB) Glyph Studio Mini.

Oh, also: is there software capable of verifying the integrity of a disk partition?

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PostPosted: Mon Aug 27, 2018 2:22 pm 
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I think Apple hopes the journal will correct filesystem damage and just leave behind corrupt files, rather than a corrupt filesystem. I'm personally glad Apple doesn't harass me every time it replays the journal. Ugh. In the bad old days, Macs used to scold you about shutting them down properly after rebooting after a crash, and I'm pretty sure this enraged a few people to the point of smashing their computers.

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