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TimeMachine to a new usb hdd has been running for over 36-hours. In desperation, I stopped the backup, I ran tmdiagnose and then started DiskUtility FirstAid. I read a little more about the situation, and am thinking of returning the disk. Or maybe I need to calm down. After 36-hours 261gb of 650gb had been backed-up, and I pulled the plug.

  • Catalina (10.15.7)
  • internal 1tb SSD (650-gb full, APFS)
  • 16gb ram, intel i5-2.5ghz
  • 4tb (MacOS-extended journaled) usb3.2 HDD (new, directly plugged-into mid-2012) macbookPro.
  • nothing else on usb bus and only web browsing on the macbook while waiting.

Is a first TimeMachine backup from that setup expected to take a few days?
Should I return the 4-tb hdd?
Does running FirstAid on a partially finished TimeMachine mean I should re-format / re-start the TimeMachine back-up?
Before FirstAid, I ran tmdiagnose with the results viewable in /tmp. What are some key features to look at? I've got several more days before FirstAid and TimeMachine ever might finish. I feel like I need to return the drive. Should I really just keep waiting?

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  • What rotation speed is the external HDD? 5400RPM? 7200RPM? Perhaps an external HHD with a Thunderbolt 1 connection would be faster. I used to use them on my Macs a few years ago before I was forced to USBC.
    – IconDaemon
    Commented Aug 21, 2022 at 16:05
  • yeah. This has 5400 rpm. I almost got a 7200 rpm disk which has same $, larger, needs its own power supply. I'd though the 5400 rpm would take a little longer, sit in the corner, quietly do TimeMachine. But, this is not acceptable.
    – davewp
    Commented Aug 21, 2022 at 16:32
  • There’s no reason a slow 4 TB disk can’t back up a 1 TB ssd if you are patient and prevent it from sleeping and interrupt backups that are large in file change count. Especially if you can let the HDD remain HFS+
    – bmike ♦
    Commented Aug 21, 2022 at 17:38
  • Is it an SMR (shingled magnetic recording) drive? Most cheap, small, bus powered drives are SMR. That may be your problem. Though it refers to CCC, read bombich.com/kb/ccc6/choosing-backup-drive
    – Gilby
    Commented Aug 21, 2022 at 23:32

1 Answer 1

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You probably don’t need to return the drive. Trying to wait or repair this drive is futile and distracts from your good instinct to determine if the drive is working.

It’s not optimized for having the first backup interrupted. It's likely IO bound on operations and seeks - not for normal copies.

Here’s how to proceed.

  1. Remove it from time machine as a destination.
  2. Erase the drive (that should take a minute or two max)
  3. Go into options for Time Machine - exclude the Users folder and exclude all connected external drives
  4. Watch how long it takes to back up just your Library and Applications
  5. Let two more backups happen

Once you're sure the drive is working - choose a time when you can let it chew through all your home folder and then remove the /Users exclusion. Or add in small chunks of data so you can not interrupt a large backup, since it has to redo all the work and then re-complete the long backup. That interruption tripled or worse the load / IO needed to complete that interval. Better to start with smaller chunks of data in this case. Large files are easy to backup - thousands of small ones is what's hurting you here.

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  • awesome. will do. i assume the stuff in iCloud is ignored.
    – davewp
    Commented Aug 21, 2022 at 16:33
  • No, you will back up every bit of metadata for every iCloud file - they are not ignored @davewp
    – bmike ♦
    Commented Aug 21, 2022 at 16:34
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    TimeMachine started hanging for over 1-hr with the "Preparing backups..." message. I tried the old 2tb TM drive and, no problem / super fast because of the excluded dir. And now, for a 2+ hours, the "Cleaning Up..." message. I feel confident that when this "clean up" finishes, I can swap to the new 4tb drive. With all the excluded dir, the 1st bkup to the 4tb drive should be fast. Then little by little, I'll add in more dir to that bkup. This sounds like a plan. thanks you!
    – davewp
    Commented Aug 21, 2022 at 22:13
  • Yes. Once you realize you have to “nurse” it in small chunks - you can manage with slower storage. Even USB based SSD can choke on a big interval and they run so hot, an inexpensive and slow spinning drive still has valid use cases for backups. Clean up - you have to wait for that unless you’re prepared to wipe the drive
    – bmike ♦
    Commented Aug 21, 2022 at 22:36
  • I got it! I am so sorry. The issue was that I had an old dev project whose dataset was 5,000+ small text files. With those backed-up on OneDrive long ago anyway, I took "rm -rf *" to that data, did similar to another proj, and I'm in Time Machine heaven. So happy I didn't return the drive, or go with one that needs its own power supply. But nuking that many files with "rm -rf *" on an SSD takes several min which seems strange. But I totally get why TM had trouble with so, so many small files rather than overall size. Sorry for not analyzing this better, and thank you!
    – davewp
    Commented Aug 28, 2022 at 19:28

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