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TIL: Apple Broke Time Machine Again on Tahoe

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Re: TIL: Apple Broke Time Machine Again on Tahoe

#151

Post by raattgift »

btreesOfSpring wrote: post #25

I have been trying to trouble shoot a Time Machine issue since upgrading to Tahoe. It is usb backup. So far none of the most recent stated fixes work. An initial backup on newly formatted disk will run but very slowly. Perhaps reaching 100% but it never finishes. At some point the percentage will change and the backup will stay stuck at somewhere near 10%. Cancel backup and run it again. Gets to ~10% and stays stuck.…

In a terminal window run

  log stream --predicate 'subsystem == "com.apple.TimeMachine" AND NOT (category == "LogLimits" OR category == "VolumeViewModel")' --info --debug --style compact
and then start a backup (either from the menu bar icon, the system settings panel, or "tmutil startbackup"). This will tell you what Time Machine is doing, and might give you some useful information.

  man log
where you can use "show" and a lookback period instead of "stream".

  man tmutil
is pretty decent documentation, although the glossary secdtion ("BACKUP STRUCTURE") is important to understand if reading the whole man page.

Some things to look out for are what filesystem your newly formatted external volume is (APFS might not be great for a single spinny disk, for example), and what version of USB is in use (friends don't let friends do USB 2 mass storage). With inexpensive external media it's often a cable or power supply issue, even if (as in your case) tar appears to work. Have you checked that the contents of the tar file are correct? Also, tar files tend to be streamed out to sequential LBAs, where smaller files and (in Time Machine backups) holes might lead to a different write pattern that the drive might not like. Maybe test with rsync -c instead of tar?

Re: TIL: Apple Broke Time Machine Again on Tahoe

#152

Post by tapete1 »

Aurornis wrote: post #11
ndegruchy wrote: post #2

I use the same setup and was able to restore some files I recently deleted. My SMB settings in Synology were set to what the recommended settings were already. Not sure what happened in this person's case, but it also seems like he backed up and didn't test the restores. Which isn't good practice.

> but it also seems like he backed up and didn't test the restores. Which isn't good practice. For a professional devops person managing a custom backup solution, I agree. For someone using mainstream consumer technology on a consumer laptop, it's not realistic to expect this. It needs to just work.

This is true. If the user was capable of testing his backups, he would not be using a Mac in the first place.

Re: TIL: Apple Broke Time Machine Again on Tahoe

#153

Post by tonyedgecombe »

fragmede wrote: post #145
tonyedgecombe wrote: post #19

Earlier quoted context omitted.

Yeah, it sounds a bit high to me.

People with laptops that don't want to be attached to a dongle for storage when there's the Internet sounds like < 5% to you?

The original post was about people who backup to a local server, not over the internet.

Re: TIL: Apple Broke Time Machine Again on Tahoe

#154

Post by hughw »

crazygringo wrote: post #72
hughw wrote: post #27

The bigger question is why does Time Machine continue use a network file system for backups? It's so fragile you can't rely on it. It's gotten better in recent years, possibly due to APFS, but that just means somewhat longer intervals between disasters (wipe out and reinitialize, losing all your backups). A T.M. using a custom protocol to save and restore blocks would fail sometimes too, but not ruin all your existin…

> The bigger question is why does Time Machine continue use a network file system for backups? As opposed to what? When you need to be able to back up to a drive on your network?

Mounting a file system on a network share tightly couples the client to the server. It’s synchronous and it’s easy to leave the file system in an inconsistent state. Much more robust to build an asynchronous protocol with your own logic as rdbms do. You don’t see rdbms mounting remote file systems do you?

Re: TIL: Apple Broke Time Machine Again on Tahoe

#155

Post by varenc »

vivzkestrel wrote: post #127
varenc wrote: post #123

Earlier quoted context omitted.

you're probably backing up things that change very often you don't care about? Figure out what's taking up space in each backup and use `tmutil excludepath -p `.

i excluded a whole bunch of things, i did not run out of space. my SSD actually blew up. it has become unusable, i cant even open it anymore

Damn... my only guess: time machine backups are VERY write heavy. Is it a reputable brand of SSD? Is time machine frequently erasing old backups? Many external portable SSDs that work fine for regular consumer uses, might struggle to handle the write volume of time machine backups. I've used 2 external SSDs with time machine and never had them fail. (T7 Samsung SSDs)

Also you'd want the SSDs to be much larger than what you need to backup. If they're small, then time machine will have to erase the older backups to make new backups, which just leads to more rewrites, stressing the SSD more. The ones I used were 4TB, but a clean first backup of my system was only like 250GB (because many things excluded). And then daily incremental backups are like 1-3GB.

Re: TIL: Apple Broke Time Machine Again on Tahoe

#156

Post by TMWNN »

ndegruchy wrote: post #33
maxkfranz wrote: post #30

I'm a big fan of SuperDuper [1]. I use it for daily differential backups to a secondary SSD. I don't get the hourly backups that TimeMachine has, but my SuperDuper backups are directly bootable in the event that my system disk dies. I'm sure you could do the same with cron and rsync, but I can't be bothered. [1] https://shirt-pocket.com/SuperDuper/SuperDuperDescription.ht...

This has been on my to-buy list for a while. Something I should probably do, because while recovery from the built-in recovery interface is fine, having an offline bootable backup is also great. It also doesn't interfere with having Time Machine be the "standard" backup. I could probably setup a calendar appointment to dump a bootable image once a month to an external disk.

>This has been on my to-buy list for a while.

While I agree that SuperDuper! is worth buying, it is free to use for whole-disk backup/cloning. The paid version enables smart copying (that is, only copying files changed since the last backup).

Re: TIL: Apple Broke Time Machine Again on Tahoe

#157

Post by cromka »

crazygringo wrote: post #76
doawoo wrote: post #59

Earlier quoted context omitted.

This 100% - it’s funny how it’s actually more reliable in my experience to use the encrypted sparse bundle. I can sling it over to my NAS no problem. I’ve restored from one and everything was perfectly fine. YMMV of course

That was my experience at first, but then it gets corrupted somehow and you have to delete it and start over. Happened to me multiple times with RAID 1, so pretty sure it's a software error -- I eventually just gave up.

Same here, lost my backup 3 times across some 6 years. Gave up and moved on to Kopia.
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