Really dumb question about Disk Utility HD clone

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stream41


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Hi folks - just a quick question. When the Disk Utility does a clone of a HD, how much space does it need? In other words, if you're cloning a 128GB drive, but only about 40GB of the drive is used, do you need 128GB free on your backup drive, or will DU only need 40GB of backup space?

I'm trying to decide if I can get by with a 64GB USB thumb drive for backup, or if I'll need to purchase a 160GB external USB drive. It's very unlikely that I'll ever exceed 50GB or 55GB on my active partition (all my media, etc is on other drives), so I'm thinking a 64GB thumb drive would be perfect.

Thanks!
 
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Lifeisabeach


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stream41 said:
Hi folks - just a quick question. When the Disk Utility does a clone of a HD, how much space does it need? In other words, if you're cloning a 128GB drive, but only about 40GB of the drive is used, do you need 128GB free on your backup drive, or will DU only need 40GB of backup space?

I'm trying to decide if I can get by with a 64GB USB thumb drive for backup, or if I'll need to purchase a 160GB external USB drive. It's very unlikely that I'll ever exceed 50GB or 55GB on my active partition (all my media, etc is on other drives), so I'm thinking a 64GB thumb drive would be perfect.

Thanks!
Click to expand...

Firstly… backing up to a USB thumb drive would be agonizingly slow. A Lexar JumpDrive, for example, has a write speed of just under 5 MB/sec. An external HDD has write speeds of 50 MB/sec or greater, depending on the model.

That said… I don't know about Disk Utility in particular, but Carbon Copy Cloner definitely will only use as much space as needed.
 
vansmith

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You can't backup more content than you have on a partition. ;)

lifeisabeach makes a good point about write speeds (if this is a concern for you). Take a look at the write speeds of the devices that you're considering. What thumb drive do you have and what external are you considering?
 
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stream41


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Yeah, just noticed the write speed on the USB thumb drive is pretty bad - 10MB/sec. I'll probably go with a used 160GB 2.5" SATA drive and an enclosure. So the size of the DU clone won't be an issue. Thanks guys!
 

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