How to limit the amount of disk space Time Machine will use?

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How to limit the amount of disk space Time Machine will use?

On Yosemite, how do you limit the amount of disk space Time Machine will use?

I'm using a Seagate Goflex Home 2tb drive connected to my router as a Time Machine backup drive. I use this for three things 1)Time Machine 2) an occasional backup of windows document subdirectory 3) backup of music and photos for long term storage. Doing something like re-partioning the drive is not an option. I'll just go buy another drive for time machine's sole use. In addition, using software from Seagate is not an option. I don't want to use their software for different reasons (mainly the GoFlex home is really designed as a "media server" which I don't use. I, of course, use iTunes. 🙂 ) On the Mac, I'm only using about 250GB total but time machine is rapidly using up space.

Apparently using a terminal command like below, used to work, but no longer works under Yosemite.

For a limit of 100gb the number below would be 100 x 1024

sudo defaults write /Library/Preferences/com.apple.TimeMachine MaxSize 102400

To remove the limit, use the following command:

sudo defaults delete /Library/Preferences/com.apple.TimeMachine MaxSize

Now, I'm not too familiar with terminal and I'm not about ready to issue a command without knowing exactly what it is going to do.

Is there an easier "switch" someplace or an app that does this?

If I don't limit the size, at some point there will not be any space left for windows backups and additional photo and music files.

iMac (27-inch, Late 2012), OS X Yosemite (10.10.1)

Posted on Dec 15, 2014 3:50 PM

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Answer 1

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Kim Hill1

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Jan 23, 2015 9:25 AM in response to rpierry

I'd like to know this too.

Are we sure that the terminal command no longer works under Yosemite?

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Answer 2

rpierry Author

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Jan 23, 2015 10:19 AM in response to Kim Hill1

I do not know for sure that this is command DOES NOT work.

I am very new at using a Mac and I do not want to use terminal until I am SURE that the command I use will work.

Western Digital is advertising a hard drive that can be connected to your router that has a special "slider" that allocates space to time machine. For others, more experienced than me, repartioning a hard drive is a simple task. I'm looking at it like simply buying a new piece of hardware is the easiest, safest thing to do.

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Answer 3

Kim Hill1

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Jan 23, 2015 10:23 AM in response to rpierry

Thanks. I think it's highly unlikely that there would be a negative effect, given the high profile of this hint. But your caution is laudable.

Repartioning a hard drive really is a simple task, if the disk is new. Use Apple's "Disk Utility." No need to buy the WD. Of course, wireless access is handy.

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Answer 4

rpierry Author

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Jan 23, 2015 10:39 AM in response to Kim Hill1

what is currently on my goflex home is 4000 digital photos, and 5000 songs not to mention $60,000 worth of work backups. I have all this backed up on a least 2 other devices. The photos and music are additionally backed up at another location. What I'm worried about is losing the goflex which is my primary backup.

given the value of the data-$150 for another drive is worth it. In addition, being 4 years old, the goflex is reaching the end of its service life. For me, time machine is doing its thing- I like the ability to immediately go back an hour or a day or a month and grab one file.

This problem is a typical Apple problem- use their product (time capsule) as it is intended to be used and you'll have no problem. Use a similar product and it will do what you want but you are on your own. In addition, all references to this problem I can find on the web are before Yosemite came out. I'm really looking to verify the above command works on Yosemite.

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Answer 5

Kim Hill1

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176 points

Jan 24, 2015 2:57 AM in response to rpierry

I tried the Terminal command, and always got this message:

"Could not write domain /Library/Preferences/com.apple.TimeMachine; exiting"

No harm done, but it looks like the Terminal command does not work in Yosemite. If anyone knows of an alternative…

Not sure about this one:

Limiting Time Machine backup size onto external drive

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Answer 6

Kim Hill1

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Jan 24, 2015 3:03 AM in response to Kim Hill1

Hmm- added "sudo" and there was no error reported:

sudo defaults write/Library/Preferences/com.apple.TimeMachineMaxSize xxxxxx

I guess we'll see.

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Answer 7

irhm

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May 10, 2015 3:13 AM in response to rpierry

I had the same question, running Yosemite 10.10.3. with 2TB Seagate USB drive I also wanted to use for backing up my Google Nexus and wife's iPad.

I took the plunge and issued this command from Terminal:

sudo defaults write /Library/Preferences/com.apple.TimeMachine MaxSize 1024000

you can check it has taken effect by going to the file /Library/Preferences/com.apple.TimeMachine.plist and using Get Info - in my case the MaxSize tag of the XML was near the end with the value I entered. Warning - do not be tempted to drag this content to TextEdit, as it can corrupt the file (as I found by experience)

I don't think there is anything different about this feature in Yosemite.

However, in the Time Machine preferences screen, it still says 1.31 TB of 2 TB available, so it has not taken this restriction into account. I've yet to fill up the space to see if it really works though.

It's still a mystery to me why Apple haven't included this option in the the Preferences screen, as it seems to be a common requirement, and much more flexible than partitioning the disc. But then Apple's mindset is very mysterious...

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Answer 8

Barney-15E

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May 10, 2015 5:50 AM in response to irhm

To limit space used by Time Machine, you create a partition on the hard drive to the size you want and set Time Machine to use that partition.

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Answer 9

irhm

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May 10, 2015 8:08 AM in response to Barney-15E

Would you say partitioning is a better solution than setting the MaxSize parameter? What are the pros and cons?

Maybe better performance, but not a big issue for backups.

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Answer 10

iW00

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May 10, 2015 8:48 AM in response to irhm

irhm wrote:

Would you say partitioning is a better solution than setting the MaxSize parameter? What are the pros and cons?

Maybe better performance, but not a big issue for backups.

Pros: You have a designated location for your backups and you are not messing with it by adding/removing additional files. It is recomended to have a separate disk/partition for a system backups. Plus, changing value of MaxSize parameter is not officially supported... But this is your call and you do whatever you want to do...

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Answer 11

Barney-15E

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May 10, 2015 11:07 AM in response to irhm

irhm wrote:

Would you say partitioning is a better solution than setting the MaxSize parameter? What are the pros and cons?

Maybe better performance, but not a big issue for backups.

Yes. Partitioning off a drive is a supported way to limit backup size. Using an undocumented hack will eventually fail to work as Apple removes it from the system.

Many of the undocumented adjustments may have been placed there for testing, not production. Also, they may have been there because they were trying to make that function work, but found it didn't, so they removed it from the interface.

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Answer 12

irhm

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May 11, 2015 12:04 AM in response to Barney-15E

Thanks guys, those are useful points. Maybe I need to find the offical Apple document on what is and is not supported in OS X...

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Answer 13

rpierry Author

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May 11, 2015 5:39 AM in response to rpierry

I never issued the terminal command and I didn't want to repartition the drive because of the value of the other (windows) data on that goflex. Time Machine used up all the space on that drive and performance dragged to a halt. It dropped from about 10megs per second though put to about 2.5megs per second. This dramatically increased backup time.

My solution is simply to buy another hard drive and partition it when new into both Mac and windows space and then use the new drive to backup the Mac and use the old drive to backup windows. This was throwing $150 at the problem. It does have the advantage of now I have "really important" stuff on two drives.

At some point, I'll issue the terminal command listed above on one of the drives and see what will happen.

Thanks for all your help.

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