TimeMachine filling local hard drive even though external drive selected for backup

[MontyC]

Hello. I have a Mac Studio M1 running on macOS 14.0 (23A339). TimeMachine backup are set onto a Synology NAS and has been reliably working for a while. Yesterday I noticed that my Studio hard drive was almost full (with 250GB in System Data - normally that is 6GB?) and discovered a bunch of local backups (example com.apple.TimeMachine.2023-09-20-171809.local). I deleted those and the drive was back to normal - being 50% full. Today, I found that over night more local TimeMachine are there filling up the hard drive again.

I can still browse the NAS TimeMachine backups and can't see anything strange in the TimeMachine settings. Any help would be really appreciated. Thanks.

 

[Fishrrman]

My advice (like a broken record, "there he goes again!"):

STOP using time machine.
START using either CarbonCopyCloner or SuperDuper for your backups.

Both are FREE to download and try.

 

[Brian33]

Time Machine is designed to make "local snapshots" every hour and delete them when they reach 24 hours old, or (from what I've read), when macOS detects that storage space is getting constrained. Usually this works fine.

I wonder if you may have some very large files that are frequently updated. For example, virtual machine storage "virtual disks". These are usually one large (potentially very large) file, and get updated constantly while the VM is running. TM would be making backups of the VM storage state every hour, and keep them for 24 hours on the same volume that the VM storage is on.

The solution to this would be to exclude VMs from TM backup and use another means for VM backup for them. (You probably don't want to back up VMs while they are running, anyway.)

 

[MontyC]

Thank you for your replies

 

[BrianBaughn]

I'll add that I use Time Machine along with TimeMachineEditor…which requires TM to be on "Manual". This seems to result in there only being one TM snapshot on my Mac.

I have TimeMachineEditor set to back up once per day but I don't know why a more frequent schedule would be any different.

TimeMachineEditor

tclementdev.com

 

[gilby101]

I have TimeMachineEditor set to back up once per day

I hope you realise that TM has the option to backup once a day (and once a week). You don't need TME.

 

[BKDad]

There's a page about this on Apple's website: About Time Machine local snapshots

It sorta suggests that being in manual mode stops the local snapshots, since placing TM in manual mode deletes the snapshots. But, it doesn't explicitly say that. That would explain why Time Machine Editor doesn't accumulate snapshots.

 

[BrianBaughn]

I hope you realise that TM has the option to backup once a day (and once a week). You don't need TME.

Yes. I mis-remembered. My TM is set for every three days via TME. I have a CCC backup every day.

As to snapshots…if I remember correctly…when I have my TM running via TimeMachineEditor (with "Create local snapshots every hour" unchecked) I always have one snapshot and it doesn't change until the next TM backup happens.

With Time Machine set to "daily" I think there's also only one snapshot stored but it changes every hour. It doesn't seem to be piling them up. If TM is set to daily and the TM disk is not attached the snapshots start piling up. Not sure if there's a limit to how many.

 

[BKDad]

At this point, I am curious what the advantage of TM is compared to setting up Carbon Copy Cloner to do hourly (or whatever) updates. TM is built in and convenient, but otherwise?

 

[gilby101]

At this point, I am curious what the advantage of TM is compared to setting up Carbon Copy Cloner to do hourly (or whatever) updates. TM is built in and convenient, but otherwise?

In my view (and I know who will disagree):
For a straight forward backup of your system/boot volume there is very little difference. Both are reliable.
If you want more flexible choices as to what gets backed up and how long it is kept, then CCC is good.
So difference is configurability. I don't see the point of CCC if you use it in the same way as TM.
I use both CCC and TM on my system/boot volume disk, but backup other volumes with CCC.

 

[BKDad]

Good information - thanks.

I already use CCC for backing up volumes from a RAID system onto separate drives, so there's no further expense here. I also back up the SSD on the Studio using CCC, but not hourly or even daily. But, TM does what it does hourly.

I've just read a number of scary stories about TM mixing things up that it's gotten me to wonder about changing my strategy going forward. At some point, I'll update to Sonoma from Ventura when the scary stories about Sonoma subside. (I was hoping that this macOS would be more Sonoma Leopard like, if you get me...) Of course, you mostly hear the scary stories, not the successes.

Update - I'm going to try CCC hourly updates in parallel to TM for a while on new, separate external SSDs. If CCC ends up being better, then I'll stick with that and set TM to "manual".