Can't reduce size of Time Capsule Time Machine sparsebundle

Question

Level 1

8 points

Can't reduce size of Time Capsule Time Machine sparsebundle

I'm having trouble following http://pondini.org/TM/A8.html to reduce the size of a Time Machine sparsebundle image on my Time Capsule (model A1302 with firmware 7.6.8). My machine is a 2016 MacBook Pro running MacOS 10.12.4. The Disk Utility screenshots on the Pondini page differ from what I'm seeing, and when I change the partition size Disk Utility creates a new one called "Untitled" in the vacated space which it won't let me delete without increasing the Time Machine Backups partition back to the full size of the disk, which seems wrong. Am I doing something wrong?

I did some more searching around and found http://hints.macworld.com/article.php?story=20071108020121567 which suggests using "hdiutil resize -size 500g -shrinkonly /Volumes/Network_Drive_Name/path/to/timemachine.sparseimage" instead. This seemed to do the job, but then the sparsebundle pinged back to its original size. I guess Time Machine did it so I need to do the file locking steps recommended by Pondini. Is this a better way to do than Disk Utility now?

Time Capsule 2TB 4th Generation-OTHER, Mac OS X (10.7.2), Time Capsule firmware 7.6

Posted on May 3, 2017 3:06 PM

Reply

Answer 1

kmbro Author

Level 1

8 points

May 3, 2017 6:52 PM in response to kmbro

Hmmm ... looks like I was wrong - Partitioning Time Capsule says it can be done exactly as you suggested. Sorry Bob. I'll be upgrading the disk on the TC at work next week so I'll give it a go. Proper partitions sounds like a much better bet than messing with sparsebundle configs!

Reply

Answer 2

Kappy

Level 10

362,007 points

May 3, 2017 3:16 PM in response to kmbro

Jim Pondini died two years ago. The site is not maintained, therefore, it contains information that may have changed or no longer applies to newer models.

I don't know why you are trying to shrink the size of the backup. It's completely ill-advised and could/will render the backup useless. You would be better off reformatting the drive.

Reply

Answer 3

kmbro Author

Level 1

8 points

May 3, 2017 3:28 PM in response to Kappy

I'm sorry to hear of Jim's passing.

To answer your comment, I want to restrict the size of the sparsebundle on my Time Capsule for the same reason as everyone else who followed those instructions - the backup expands to consume the entire available space and, because it's a Time Capsule, I cannot partition the disk to constrain it. Basically I want to use one Time Capsule to back up three machines without one of them consuming all the space to the detriment of the others.

Reply

Answer 4

Kappy

Level 10

362,007 points

May 3, 2017 3:44 PM in response to kmbro

That is normal. And, it is why the backup drive should be at least 2-3 times the size of the backed up drives. Time Machine is an aggregating backup system that stores all files including changes to those files to enable you to restore files from the past prior to changes. It's referred to as an archiving backup. If you don't want that, then you need to use a different backup utility for use with an external drive, but not with the Time Capsule or Time Machine. Furthermore, regardless of what type of backup you do, you should never use the backup drive for other storage.

What you are trying to do is to partition the Time Capsule drive. By doing so you will limit the backup capacity to the capacity of the partition. I recommend against doing that. If you need external storage then buy an external drive but do not use the Time Machine drive for that purpose.

Reply

Answer 5

kmbro Author

Level 1

8 points

May 3, 2017 4:01 PM in response to Kappy

I am NOT trying to partition the Time Capsule drive. I know I cannot do that. What I AM trying to do is create 3 Time Machine sparsebundle VIRTUAL drives on the single Time Capsule PHYSICAL drive and then restrict the amount that each of them can grow to so that no one virtual drive locks out the other two. It's very easy to create the 3 sparsebundles - I just tell each Time Machine on each computer to use the Time Capsule. The tricky bit is changing the upper limit on the sparsebundle size. Note that this is different to changing the BACKUP size - I'm attempting to reduce the sparsebundle partition size before the disk space is ever used, so it's perfectly safe - or it would be if Time Machine didn't keep resetting the sparsebundle size back to the size of the entire disk. I've done the "Locked" hack to the Info.plist files now so let's see if that will hold.

Please remember that a sparsebundle does not occupy the entire amount of disk space implied by its size - it only grabs space from the host physical drive when it runs out of free blocks, and then only up to its maximum configured size. At this point, Time Machine happily starts discarding old backup information, just like it does on a physical external drive that it fills up.

Reply

Answer 6

Kappy

Level 10

362,007 points

May 3, 2017 4:12 PM in response to kmbro

Yes, I know about sparsebundles. But why do you want these three sparsebundles? If you are planning to use the same drive to backup three different computers, then Time Machine will do that automatically when configured by another computer. However, you have no way of controlling this.

Reply

Answer 7

kmbro Author

Level 1

8 points

May 3, 2017 4:31 PM in response to Kappy

Why do I want 3 sparsebundles? Because that's what Time Machine creates when I point 3 separate machines at the same Time Capsule.

We've already established that these 3 instances of Time Machine are acting independently and greedily, each one grabbing as much physical space as it can before it starts pruning old backup information.

This is what happened on the Time Capsule we use at work - the Mac mini server consumed most of the space so the 2 MacBooks have to keep on purging the meagre amount they were able to grab before the mini filled the disk. Fortunately sparsebundles don't relinquish physical blocks when they clear files out of virtual blocks so at least the MacBooks can keep what they already have.

I want to avoid this situation in my setup at home. The ONLY way to do that on a Time Capsule is to nail the upper size of the sparseimage files to something less than the size of the physical disk. The Pondini instructions show that this was possible with a previous version of MacOS. It looks like it should still be possible with 10.12.4. If anyone has experience of this then please join in.

Reply

Answer 8

Kappy

Level 10

362,007 points

May 3, 2017 5:02 PM in response to kmbro

OK, so you have three machines backing up to a single Time Capsule that is not large enough to assure that the capacity is a minimum of 2-3 times the capacity of these three drives.

Why isn't Pondini's method workable now if it was before? Can you point me to what you are using off of the Pondini site? At least I might see what it is.

Who did the setup at work? Can they help you with your home setup? They have some experience. Personally, I do not recommend what you want to do. I would suggest three separate backup drives on each machine.

Reply

Answer 9

kmbro Author

Level 1

8 points

May 3, 2017 5:31 PM in response to Kappy

Yes, I have 3 machine to back up.

No, the Time Capsule IS large enough - I installed a 6TB drive so there's 2TB for each Mac. Plenty!!

The problem is that Time Machine on each Mac will attempt take the ENTIRE 6TB if I leave them running long enough.

I want to restrict each Mac so it can only take 2TB.

I was looking at http://pondini.org/TM/A8.html as I said in my original post. The problem I came across, again stated in my original post, is that when I went into Disk Utility and attempted to shrink the Time Machine Backups partition in the sparsebundle, Disk Utility created a second partition called "Untitled" in the (virtual) space vacated; it didn't reduce the (maximum) size of the virtual disk. Perhaps this doesn't matter - the second partition will never be used, so the sparsebundle will never attempt to grab that space from the underlying physical disk, so I guess it effectively restricts the sparsebundle's size to the size of the now-shrunk Time Machine Backups partition. Pondini's instructions are silent about the existence of a second partition, so I'm unsure whether this is what I should expect.

The "hdiutil resize" command, on the other hand, does exactly what I'm expecting - it reduces the size of the Time Machine Backups partition and it reduces the (max) size of the sparsebundle virtual disk too.

So that's the crux of the question. Is this mysterious "Untitled" partition the thing I should be expecting, and does it magically cause Time Machine to NOT keep trying to expand the sparsebundle to the full size of the physical drive?

Right now I'm running with 2 machines, both with their sparsebundles shrunk using the "hdiutils resize" method, supported by Pondini's advice to lock the Info.plist file and its backup.

Oh, and who set things up at work? Me :-)

Reply

Answer 10

Kappy

Level 10

362,007 points

May 3, 2017 5:41 PM in response to kmbro

I would suggest, then, using hdiutils to set up the three partitions. I've never done this since I don't try backing up multiple machines to a single Time Capsule. Not being a Time Machine user I also do not use a Time Capsule.

Reply

Answer 11

Bob Timmons

Level 10

185,474 points

May 3, 2017 5:45 PM in response to kmbro

- I installed a 6TB drive so there's 2TB for each Mac. Plenty!!

Probably water under the bridge at this point, but It would have been a simple matter to partition the new drive into 3 separate 2 TB partitions before you installed it in the Time Capsule. All that you would have needed was an inexpensive USB to SATA caddy or enclosure for the setup.

Then, you could have used Disk Utility to set up the 3 partitions that you needed, and then installed the drive in the Time Capsule.

Since you already know how to open up the Time Capsule and pull the drive, you might consider doing this if you want to be sure that you really do have the 3 separate 2 TB partitions that you are looking for.

Reply

Answer 12

kmbro Author

Level 1

8 points

May 3, 2017 6:13 PM in response to Bob Timmons

Sadly not. If you put a partitioned disk in a Time Capsule then it reports a disk error and forces you to allow it to reformat the disk with a single partition. Hence the need to simulate partitioning by choking the size of the sparsebundles :-(

Actually the TC does create more than one partition - there are a couple of tiny hidden ones where it stashes control information. You can see them on a "pulled" disk if you stick it in a USB caddy (I did that). But for all practical purposes there's only one user-accessible partition, and you can't add more.

Reply

Answer 13

Bob Timmons

Level 10

185,474 points

May 3, 2017 6:47 PM in response to kmbro

Not my experience at all, but this was a few years ago, and I was using a different version of Disk Utility and the older "pizza box" version of the Time Capsule. Things worked fine for a year or so, until the power supply blew up.

Reply

Answer 14

May 3, 2017 8:55 PM in response to kmbro

My experience is like yours.. it used to work.. long long ago. (not sure about Galaxy far far away)..

But even more recently it was no longer possible to partition even with the disk out, without getting disk errors.. this did not stop the TC from working.. but it was always telling you about the disk errors..

I did spend some time after getting access to the TC firmware to do it via NetBSD commands.. but got nowhere.. it still refused to handle a multiple partition drive.

I have my notes on commands if you are interested talk to me.

Email is here.

https://sites.google.com/site/lapastenague/a-deconstruction-of-routers-and-modem s

Reply

Answer 15

jsliff

Level 1

16 points

Jun 14, 2017 9:11 PM in response to kmbro

Jumping in late here - but I was just on the phone with Apple trying to do something very similar. First, the "Partitioning" page you are looking at is 5 years old and things have changed. The "Pondini" page - even older - clearly states that it "may" work with certain operating systems but may not, and obviously doesn't address Sierra.

If you're accessing the Time Capsule via wifi you shouldn't be able to see it in disk utility at all, and if you do it will not respond like a "normal" disk. The only way to partition it is if it's connected directly, and to create new partitions requires erasing the current backups.

You're repurposing the drive from a time capsule to either multiple time capsules or time capsule(s) and storage - either way it has to be erased and partitioned, not repartitioned. You can create multiple partitions and treat each as a separate backup for Time Machine to use, but you can't control the size of sparse bundles. They are created and sized dynamically *only*. In the past they could be fixed in size, but that was in previous operating systems and is no longer true.

None should be using the entire free disk space and choking out other backups if all are running a reasonably updated version of OSX. I've run up to three backups for different machines of vastly different sizes and never had that problem. It was still something I asked about as I was concerned it might happen.

You can get a callback from Apple support about 5 minutes - I suggest talking to them rather than trying to use 4-5 year old directions from website or even Apple's community pages.

Good luck!

Reply