Time Machine has eaten all start-up HDD space!

[Karvel]

I've bought a new WD My Passport Essential 500GB a couple of days ago and after reformating it I set about it backing up my data using Time Machine. I left it on overnight to come back to it "Stopping back up...", and left it a few more hours but it still had the same status. I then restarted my iMac and noticed the main start-up drive inside the iMac now has 3.9GB which is way less than it was before I started using Time Machine.

Anyone know what this is? It's almost as if it made a replica of itself both on the external and the internal although I don't think there would be enough space on the internal to do a full replica, so I'm puzzled...

The back-up seems to have silently corrected itself though as the Time Machine System Preferences lists an earliest and latest back-up!

 

[simsaladimbamba]

Take a look at DiskInventory X (will not work in Mac OS X 10.7 Lion), OmniDiskSweeper, JDisk Report or GrandPerspective to see where your HDD space went to.

 

[Karvel]

From GrandPerspective;

What is "Miscellaneous used space"?

 

[simsaladimbamba]

From GrandPerspective;

What is "Miscellaneous used space"?

Image

I don't have a clue.
I use OmniDiskSweeper, as it sorts by biggest folder and so forth.

 

[GGJstudios]

From GrandPerspective;

What is "Miscellaneous used space"?

There are a few things you can try:

• Search with Finder to see if the space is being consumed by a very large file or several large files. Adjust the 50GB in the illustration to whatever size you deem appropriate.
  
  
• For Time Machine users on Lion, Time Machine local snapshots may be consuming space.
• Use DiskInventory X (pre-Lion), OmniDiskSweeper, JDisk Report or GrandPerspective to see how space is being used on your drive. Some of these apps may show more detail than others, so try several.

 

[Karvel]

I'm on Snow Leopard btw. Nothing appears for a search for size bigger than 50GB or 20GB strangely.

From DiskInventoryX;

And OmniDiskSweeper finishes sizing at 37.9GB;

 

[SplicedBanjo]

I had some hard drive disk space "disappear" on me recently, and using Disk Utility to repair the hard drive (after booting from an external drive) fixed it.

This would generally only be a possible solution if space is just missing and there simply aren't any files taking up the space. If you can find the files, then it is not a disk repair issue (although there's no harm in maintaining your hard disk anyway).

 

[Karvel]

Which leads me to wonder how doing a Time Machine back-up for the first time has caused Finder to report this? Has Time Machine caused it, or has there been a niggling problem with my drive that's only come to light upon doing a Time Machine back-up?

Regarding booting from my external HDD - how would I go about putting Snow Leopard on it in order to back-up from it?

Many thanks all

 

[SplicedBanjo]

Which leads me to wonder how doing a Time Machine back-up for the first time has caused Finder to report this? Has Time Machine caused it, or has there been a niggling problem with my drive that's only come to light upon doing a Time Machine back-up?

Regarding booting from my external HDD - how would I go about putting Snow Leopard on it in order to back-up from it?

Many thanks all

Why don't you just boot from your Snow Leopard DVD?

I don't know really the technical explanation behind what causes disk space to disappear, other than the fact that sectors on the disk that have been deleted somehow don't get reported to the volume "map" as being available. But it recently happened to me a second time, so there may be bugs in OS X that cause this. (I'm running 10.7.2 Lion.)