Why are my Time Machine backups failing?

[Bren]

I recently began using an external hard drive, WD Easystore 8TB HDD, connected to my Mac via USB, as my new Time Machine backup volume.


This had been working fine since late August, but yesterday I began getting a message saying the Time Machine backup had failed.

I couldn't run Disk First aid on the hard drive, because First Aid reported the volume as being currently in use, and thus unable to be unmounted. This was true even after I told Time Machine to stop using that volume for backups.

Eventually, after an unplug and restart, I was able to use First Aid to erase the volume. I then designated it again as the Time Machine backup volume, and I believe Time Machine did to one successful backup last night.

Sadly, I just got home from work to find I'm again seeing a message saying the backup failed.

The only information being provided is that there was an error creating the backup folder. The last successful backup was at 2:43 PM Pacific Time.

What is going on here? Are there system logs I can get by typing in Terminal commands that would shed some light on this?

Thank you!

[Bren]

What do I do about this? Please help me!

[obvs]

I would try going to :System Preferences:Time Machine:Options and add your whole drive as a backup exclusion, and then restart, and then go in to the same place and remove the exception.

[Bren]

Thank you. I have more than one drive, but I just added my internal hard drive as a backup exclusion. Should I give Time Machine some time to perform a backup before I remove the exclusion?

[Lombo]

Your time machine drive. Not your internal.

[Bren]

The drive itself is in grey, and can not be excluded, but I did exclude an old volume on an external hard drive named "New Time Machine Backup."

I hope this helps. LOL.

[Bren]

Backups are still failing, and Disk First Aid is still saying it can't unmount the external hard drive I'm using for Time Machine.

[Bren]

So how do I figure this out? It's maddening. Again I ask, are there Terminal commands or log files that would tell me, specifically, why the back-ups are failing, and how to solve this?

[ukimalefu]

do you have another backup? it is recommended to have more than one

If don't and you can, make a 3rd copy of your data using another method. I'd try making a disk image. There some popular backup apps but I've never used them, or time machine.

Then, get the problem drive and wipe it clean. Reformat it, and try the time machine backup again. It's all i can think of.

Oh, also, maybe run disk first aid and something like Onyx on your main drive.

I don't backup as much as I should, and when I do, I do it manually.

[Bren]

Thank you. I already reformatted the Time Machine volume, but that didn't fix the problem. I just ran Disk First Aid on my boot volume (apparently you no longer need to reboot from your recovery partition to to that?), and it found no problems.

The boot volume is a 500GB SSD, of which 23.68GB is currently free. Is it possible I don't have enough free space on my boot volume?

[ukimalefu]

Thank you. I already reformatted the Time Machine volume, but that didn't fix the problem. I just ran Disk First Aid on my boot volume (apparently you no longer need to reboot from your recovery partition to to that?), and it found no problems.

The boot volume is a 500GB SSD, of which 23.68GB is currently free. Is it possible I don't have enough free space on my boot volume?

yup, that drive is full

You should at least have 15% of it free

https://www.lifewire.com/how-much-free- ... ed-2260187

[obvs]

Ahhhh, yeah. You will probably want to have more space on your drive. It uses a certain amount of space to move files between itself and the backup.

[Bren]

OK, excellent, thank you!

[Bren]

OK, so I deleted a bunch of stuff, but now when I do a "Get Info" on my hard drive, It says "Available: 74.58 GB (56.44 GB purgeable)."

Meanwhile, Disk Utility is showing just 18.12 GB of free space, but that same numbers of 74.58 GB (56.44 GB purgeable) in the "available" category.

So, like, how do I purge that 56.44 GB, and is it important I do so?

[Bren]

This seems like a horribly inelegant solution:

https://bambielli.com/til/2018-01-07-purgeable-space/

[Bren]

And my attempt at a Time Machine backup has again failed.

[ukimalefu]

No idea what "purgeable" means. Must be something about SSDs.

[Bren]

If you click the link I posted, it explains what it is.

[ukimalefu]

If you click the link I posted, it explains what it is.

oh, duh, I should have clicked it.

That links recommends "cleanmymac", DO NOT DOWNLOAD THAT. The reason I say it is because I saw too many ads for it that makes suspect it will at least install some kind of adware, or something you don't want. And worst case, some kind of spyware or tracker or even something really bad.

That "purgeable" stuff, sounds like a cache, it speeds up things, but you don't really need it. And if you do delete it, it will get re-made (is that a word) automatically, eventually.

And sure, using some utility app may be easier and safer than using the terminal, unless you really know what you're doing.

I always recommend Onyx because it's what I know and trust. I've used it for years without any problem. I'm not sure about this "purgeable" thing, but Onyx does cleans up stuff that takes storage space.

https://www.titanium-software.fr/en/index.html

[Aaron_R]

I second OnyX. I didn't know it was still around since I quit using OS X, but when I did that is also what I used. I think the purgeable stuff also contains your index records for the search feature in OS X. So if you use it often and if I remember correctly after you delete all the purgeable files their is an option to rebuild the index (it'll slowly rebuild in the background otherwise and your search function might not fully work until it is finished).

[ukimalefu]

I second OnyX. I didn't know it was still around since I quit using OS X, but when I did that is also what I used. I think the purgeable stuff also contains your index records for the search feature in OS X. So if you use it often and if I remember correctly after you delete all the purgeable files their is an option to rebuild the index (it'll slowly rebuild in the background otherwise and your search function might not fully work until it is finished).

You mean the spotlight index? In the version of Onyx I have (for mojave, each MacOS version has its own) deleting that is optional (you may need to dig into the options to set check or uncheck that box). I don't remember the default but I have it set to never delete that index, because I hate how slow things get when indexing.

[Aaron_R]

Yep, that's what I meant. I've been out of OSX long enough I forgot what it was called

[Bren]

Oh sweet, I still have Onyx installed from a long time ago, and it's not asking me for a new serial number or anything, so I guess I can use this version. It's Onyx version 3.4.9. I'm using MacOS High Sierra, so hopefully both are age-appropriate for each other.

[Bren]

Well I ran Onyx, but I'm still seeing that 56 GB of purgeable data. I just ran Onyx with the default options selected. Any recommendations on which additional boxes I might be able to check off in order to get the desired result?

[Bren]

Perhaps I've made progress. "Get Info" is still showing just 18GB available, but the purgeable date is now showing as 569 MB instead of 56 GB.

And a Time Machine backup apparently succeeded a few minutes ago.

[ukimalefu]

Consider getting an external drive to off load all non essential files to, and/or have another backup drive.

[Bren]

Things are going well! I came home from work and discovered Time Machine had experienced no backup failures of the course of the evening!

[ukimalefu]

[Bren]

Imagine how lost I'd be without you people!

[Aaron_R]

So did you ever discover the problem that caused the issue, was it just a lack of storage space on the boot drive?

[Lombo]

Most likely. Time machine must copy files in a cache on the local HD I presume.

[Pariah]

The rule of thumb I have always used is you need to keep at least 10% free space. Modern OSs in prefer some breathing room.

Has TM finally been fixed? During my tenure using OSX I could never get TM to work reliably.

[Metacell]

It's always worked fine for me, though I don't do scheduled back-ups, just manual ones.

[macaddict4life]

A little late, but purgeable space means space that could be freed immediately if needed. You shouldn't need to clear it, but that's not always true. For example, and earlier version of Steam saw purgeable space as used space, and couldn't install things. I used a tool called DaisyDisk and it did a great job freeing that space. It was not free, but it was not expensive, and it did its job without ill effects or secretly being MacKeeper-style malware.