AppleDev879

macrumors newbie
Original poster
Mar 1, 2011
23
0
Hi all,

I've got a 1TB external drive connected via USB to my 1TB iMac, which I use for Time Machine. I have 93.9 GB left on the internal disk. But when Time Machine goes to make a backup, it informs me that it does not have enough space to make a backup regardless of the fact that the drive is empty and used solely for Time Machine. It is my understanding that Time Machine needs a little extra space on the disk for organizational purposes, but it doesn't seem like it should need over 90 GB! I've tried erasing and reformatting the disk in Disk Utility, but still no luck. I'd also found that prior to reformatting, Time Machine would not delete old backups from the disk. Any help would be greatly appreciated. Thanks again.
 

nippyjun

macrumors 68000
Jul 26, 2007
1,532
205
I do believe that you need a larger drive to backup your 1tb drive.

Do you have another external drive that you can temporarily move some of your data to to see if time machine works with less of your internal drive filled up.
 

waynep

macrumors 6502
Dec 31, 2009
434
0
Now *why* would he need an external drive with more capacity than than internal one?

I think I read somewhere that the recommended size for a Time Machine drive was 2x the drive you are backing up, but I can't fine that link now . . . .
 

mstrze

macrumors 68000
Nov 6, 2009
1,915
0
Now *why* would he need an external drive with more capacity than than internal one?

Because Time Machine allows you to go backwards in 'time' to recover files and the state of your drive from days, weeks or months ago. Hence, at some point you WILL have a TM partition that is larger than the amount of stuff on your internal.


The rule of thumb I had always heard is 1.5 times the size of your internal drive when looking for a drive to use with Time Machine.
 

thundersteele

macrumors 68030
Oct 19, 2011
2,984
8
Switzerland
It is recommended that you use a drive that is bigger than your internal drive for backups. But it's not mandatory.

What is the actual size of the backup drive, after formatting? Can you delete some stuff on the internal drive, or move it to some other storage space?

Currently you can't really benefit from Time Machine, so you might as well manually back up to the external drive or use a different tool to create a copy of your internal disc on the backup drive.

Also, with USB 2.0, this might take a day or so to finish.
 

AppleDev879

macrumors newbie
Original poster
Mar 1, 2011
23
0
It is recommended that you use a drive that is bigger than your internal drive for backups. But it's not mandatory.

What is the actual size of the backup drive, after formatting? Can you delete some stuff on the internal drive, or move it to some other storage space?

Currently you can't really benefit from Time Machine, so you might as well manually back up to the external drive or use a different tool to create a copy of your internal disc on the backup drive.

Also, with USB 2.0, this might take a day or so to finish.

Thanks for your help. That's disappointing.
 

Martyimac

macrumors 68020
Aug 19, 2009
2,090
1,373
S. AZ.
Not sure the other posters are correct. When I had my MacPro, I had a 1TB HD and a 1TB backup disk. Time machine worked just fine and I never had issues with running out of space. Now, granted my system disk was never more than 50% used but my TM disk only had about 20% filled up.
I would continue to look for other issues.
 
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