Time Machine Backup Keeps Growing

Question

Level 1

8 points

Time Machine Backup Keeps Growing

This is a resurrection of a late 2018 thread on the same subject. I've tried the solution discussed as closely as possible with no success. The current equipment is a MacBook Air running Mojave 10.14.6 and a Seagate 1 TB USB HDD. Mac SSD memory is reported at about 55 GB, out 0f 121GB.

The Time Machine "growth" problem was first noticed on a Synology DS218+ NAS, which had been working perfectly with Acronis True Image 2019. I've used Time Machine for years with virtually no problems with two Time Capsules and a couple of USB HDDs, so I expected similar results with the NAS. No such luck! In two days it filled up the 2 TB RAID drive. Thinking it might be some incompatibility with the NAS, I tried TM with the HDD, with the same result.

I got some help from Apple Support yesterday. We erased the HDD and ran Disk Repair on both the Mac and the HDD. That didn't change anything, so I ran a 3x secure erase which resulted in a different file format and didn't fix the problem. Today I erased again and changed the file format to Mac OS Extended (Journaled), and TM is running again. It will be a while before I know if it will work, so I thought I'd jump the gun and post this in case some geek among you is spending Sunday online and would like to help.

Posted on Aug 4, 2019 9:56 AM

Reply

Answer 1

Top-ranking reply

Barney-15E

Level 10

122,828 points

Aug 4, 2019 12:28 PM in response to emery212

For a Time Machine backup disk directly connected to your Mac, it must be Mac OS Extended (Journaled).

Unless a NAS is certified to support Time Machine over SMB (see Old Toad's link), it won't be reliable. I don't know of any that actually support that specification. They use an AFP hack to file share over AFP since Apple never licensed AFP. It has been notoriously inconsistent when used with Time Machine.

On unsupported media, it may be doing all sorts of random things. It could be generating a new full backup every time because it cannot verify the previous one.

Even on supported media, if you are backing up a monolithic database like the ones Outlook uses (or at least used to use) for your data, it will make a complete backup of the entire database whenever it changes, no matter how small the change actually was. Since the database is a single file, it doesn't know what part of it changed. Microsoft may have gone to a striped file array for their database storage, so that may not apply with newer versions of Office.

Reply

Answer 2

Old Toad

Level 10

216,196 points

Aug 4, 2019 12:16 PM in response to emery212

Does your Time Machine drive meet these specs: Backup disks you can use with Time Machine - Apple Support

Reply

Answer 3

Barney-15E

Level 10

122,828 points

Aug 4, 2019 1:00 PM in response to emery212

Time Machine does get corrupted occasionally.

You essentially have to do what was conveyed and erase the drive and restart Time Machine.

A very experienced user here named Pondini (since passed away), created a Time Machine FAQ the had lots of useful information about troubleshooting Time Machine. There are at least two sites hosting the original content, but it is getting quite stale by now. There was a section on a complete Reset of Time Machine that may still be useful, but you'll have to interpret what the descriptions apply to in the new TM preferences.

https://www.baligu.com/pondini/TM/A4.html

The reference to Outlook was to provide an example of things that use a monolithic database.

All of Apple's data stores are Time Machine friendly.

Reply

Answer 4

emery212 Author

Level 1

8 points

Aug 4, 2019 12:45 PM in response to Barney-15E

Since the problem first showed up on NAS, I suspected some sort of incompatibility, so I hooked up a USB drive that I had used with TM for many months (before migrating to Mojave). That's what I'm currently working with and encountering the same problem.

Reply

Answer 5

Aug 24, 2019 3:12 AM in response to emery212

Hi,

did you find a solution? I tried all the Synology setup options (quotas, users etc) but still having the same issue of the backup size growing till the disk is full (my drive is 250GB in total with around 1/2 full - but the current backup size is showing to be 460 of 480GB!).

cheers,

Reply

Answer 6

emery212 Author

Level 1

8 points

Aug 24, 2019 3:31 AM in response to bazancik2

No. I never found a solution. I have Acronis True Image, which works, so I temporarily stopped trying to use Time Machine. I figured that I'd return to it sometime because (other than this problem), I like the way it works but, frankly, I don't know what I'm doing half the time.

Reply

Answer 7

emery212 Author

Level 1

8 points

Aug 4, 2019 12:51 PM in response to Barney-15E

I don't use Outlook and the whole Mac is 55 GB of pretty ordinary, mostly Apple stuff. I'll go back and address the NAS if I can ever get TM to work correctly on the USB HD.

Reply

Time Machine Backup Keeps Growing

Similar questions