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PostPosted: Fri Oct 12, 2018 3:59 am 
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I had the occasion to shut my system down last night due to strong storms. When I powered everything back up this morning, I noticed – immediately upon it being powered up – that the activity light on my Time Machine drive was flashing very rapidly, as though there was already activity, when the computer had barely begun to go through its startup procedure; long before reaching the point where I would log in (all other external drives appeared idle).

After logging in, I knew that at some point, Time Machine would do its first backup, but the activity light continued to flash. Eventually, TM did begin its first backup, but this was the first time I noticed, in an open Finder window, that the eject button/icon for the TM drive had not changed to the familiar spinning clock when TM is doing its thing.

When TM finished, the drive's activity light stopped flashing and returned to a normal state. So I'm not necessarily concerned about the integrity of backups, but just curious as to whether the TM drive activity light beginning to flash long before computer startup has even finished (let alone user login) is normal. I'd never noticed it before, mostly because I rarely shut the computer down.

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PostPosted: Fri Oct 12, 2018 5:40 am 
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I believe the flashing was due to fsck running due to what it considered an untowardly shutdown of the drive.


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PostPosted: Fri Oct 12, 2018 8:12 am 
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Thanks, BD. But my puzzlement continues:

If it was fsck that ran on startup this morning (approx 7:22), then fsck – plus the Time Machine backup that ran immediately after – finished after about 25 minutes and the activity light stopped flashing and returned to normal.

FYI: my TM backup volume is a 2TB drive.

But, after reading your reply, I knew I had done a proper shutdown last night, so I wondered whether the shutdown had interrupted a TM backup in progress. So, beginning at about 10:22 this morning, I ran Disk First Aid on the TM drive.

After "Checking multi-linked files," it reported: "Incorrect number of file hard links."

After "Checking multi-linked directories," it reported: "Incorrect number of directory hard links."

When it was finished checking, DFA began repairing the volume.

It listed more than several occurrences of: "Hard links need link count adjustment."

It listed more than several: "Orphaned file hard link IDs"

It listed more than several: "Indirect nodes need link count adjustment"

After making all the repairs, DFA of course then re-checked the volume. Disk First Aid finally reported at 11:25am that it had successfully made all repairs, and I quit DFA... but the activity light continued to flash until 11:33 (the TM drive is on the Spotlight privacy list, so it shouldn't be indexing).

So... first I was curious about the activity light flashing. But, now I'm more curious: if it was fsck that had run immediately after startup, and either found no issues, or it did find issues and repaired them within a half-hour, I'm wondering what might have caused the issues that were definitely found later when I ran DFA manually and it ran for an hour.

Some of you might recall, a number of months ago, I'd reported that Disk Warrior was consistently finding my Time Machine drive's directory to be in need of replacement. That is, until someone pointed out that the very nature of Time Machine performing backups tends to alter file structure (which makes complete sense to me).

So, if that is the case, could it also be possible that the issues Disk First Aid found and repaired this morning were a result of the same type of thing? I never pay any attention to the Time Machine drive (only rarely have I even had the need to retrieve a file or two from a backup); it was only the constant flashing of its activity light that drew my attention to it this morning.

Puzzling, yes?

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PostPosted: Fri Oct 12, 2018 8:26 am 
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Yes, a bit puzzling, but I still bet it was fsck for whatever reason on startup.

Your latest experience with DFA makes me think we've got an intermittent connection, a drive going bad, or possibly a RAM issue, could even me dust on the Mobo/chips.

Do you have a second backup?


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PostPosted: Fri Oct 12, 2018 8:55 am 
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Well, let's see: the TM drive is the second of two Glyph Studio Mini drives (and the only devices) on the Firewire bus. The first drive on that bus is Audio 1, where all my recording is done, and there has never been a clue of intermittence there. My Mac mini has 16GB of RAM, and I use iStat Menus, whose menu bar displays never report any memory issues. By "dust on the Mobo/chips," are you referring to the mother board in the computer? I can certainly check for and blow out any dust in there. Lastly, the 2TB TM drive is fairly new (although I know that doesn't necessarily rule anything out), but I can always order another one. I do have an older, 1TB drive I could switch to in the meantime.

I'll start by blowing out the Mac mini. OH: is it true, when blowing out the computer, that air should be blown ONLY in the same direction as it is normally drawn into the computer? In other words, I should NOT force air into the exhaust port?

What would be your next suggestions after doing that?

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PostPosted: Fri Oct 12, 2018 9:26 am 
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Yes, I meant motherboard.

Is the mini openable? I don't have experience with
minis that don't open, but I myself would blow with the flow first, against the flow second, then with the flow again.


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PostPosted: Fri Oct 12, 2018 9:31 am 
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Yes, the mini has that round, black plate on the bottom (with a thin opening along its forward edge that acts as the air intake). With a slight twist, it comes off.

I'll do the cleaning after lunch.

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PostPosted: Fri Oct 12, 2018 9:36 am 
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:)


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PostPosted: Fri Oct 12, 2018 10:19 am 
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OK. Mac mini was very clean inside, apart from just a barely visible line of dust accumulated at the intake opening. I'd like to think what contributed to a clean(er) interior was the four 1/8-inch rubber feet I'd attached to the bottom of the mini some time ago, raising it above any dust that might be on the desk surface.

The Time Machine drive activity light is flashing again, though. Oh... it just stopped and returned to normal. But, while it was flashing, I launched Disk First Aid to check whether the TM drive was unmounted (I'm guessing fsck would unmount the disk prior to running). The disk was NOT unmounted, though.

But Activity Monitor was showing mds running, even though Spotlight indexing for the disk is disabled. Does the Mac (or Time Machine itself) do indexing apart from Spotlight?

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PostPosted: Fri Oct 12, 2018 10:29 am 
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Hmmm, good question, I wonder if there's some link or alias that is working around that drives exclusion

Is there a .Spotlight-V100 folder on that TM drive? If so what does a Get Info show for Last Modified?


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PostPosted: Fri Oct 12, 2018 10:41 am 
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There's no .Spotlight-V100 folder, but there is a .spotlight_repair folder (last modified date 2/24/18) and a .spotlight_temp folder (last modified date just a half-hour ago).

Hmmm, indeed, Mr. Holmes. ;-)

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PostPosted: Fri Oct 12, 2018 10:52 am 
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Aha! Just found this: scroll to the first reply: https://discussions.apple.com/thread/8045767

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PostPosted: Fri Oct 12, 2018 11:02 am 
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However... all this Spotlight stuff doesn't begin to explain the issues that Disk First Aid found on the TM drive.

Or, does it?

The plotz thickenz.

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PostPosted: Fri Oct 12, 2018 11:48 am 
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Doesn't explain fsck, no, but perhaps Spotlight is used behind the scenes to keep track of what has & hasn't been updated.

Unless it happens again, I wouldn't worry too much right now on the gsck deal.


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PostPosted: Fri Oct 12, 2018 12:03 pm 
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The only way Time Machine knows what's on your volume is by building indexes, which is done by reading the files on the drive or creating the indexes as it writes files to the drive.

Since your drive needed repairs, and those repairs likely affected the number of files on the drive (cross linked files are bad news, it means two or more files were listed as owning the same block on the disk, which means at least one of them is going to have data loss), it will need to create new indexes based on the actual count of actual files on the drive. This requires disk activity. Given the millions and millions of files Time Machine creates as part of its normal operation, a lot of activity after it has to discard and rebuild indexes is normal.

I normally wipe & recreate my Time Machine drive once it reaches the point of crosslinked files. Whatever problem led to the crosslinking seems to come back fairly quickly, whereas if I wipe it, it takes much longer. Time Machine is a very fragile backup system.


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PostPosted: Fri Oct 12, 2018 2:34 pm 
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Thanks, MB. Your explanation cleared things up for me.

So, with the flashing drive activity light now explained, how often would you suggest I run Disk Utility to check the Time Machine drive's integrity?

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PostPosted: Sat Oct 13, 2018 9:51 pm 
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Every week or two would probably be safe. I'm kind of paranoid here at home, I just leave console open and every couple days scroll back a bit to look at the latest Time Machine entries. When it goes off the rails it'll throw a lot of errors. I really hate to jinx myself but I'm currently in my longest-ever stretch of Time Machine not eating itself so I can't say off the top of my head what they are, it's been that long since I've seen them.


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