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You are here: MacNN Forums > Software - Troubleshooting and Discussion > macOS > Creating Disk Images with Disk Utility

Creating Disk Images with Disk Utility
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mattyb
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Sep 9, 2009, 04:45 PM
 
I have a USB attached 1TB Western Digital Hard drive. It is attached to a Feb 2007 20" iMac running 10.5.6 There is also a FW400 attached 320GB Western Digital Hard drive to said iMac.

I decided that I would 'backup' my Downloads folder using a Disk Image onto the external 1TB drive. The creation of the disk image on the external went well, but now it seems to be stuck in a copying loop. I do not have the choice to Cancel in the copying window. Looking in the finder the file 'Downloads.dmg' gets a continuously updated Modified date. When I try and quit Disk Utility I get a window that says Operations still in progress, Quitting in the middle of some operations can leave a disk non-operational. I have chosen not to quit Disk Utility. I am consistently using 30% of the 2 cores, the disks do not sound like they are being used - internal and external.

I did not choose any special attributes for the disk image file, only compression.

I presume that the warning is about the external disk and not the internal one, but wanted some advice before quitting Disk Utility. What do the experts recommend?

Bit more info : the process that is at the top for CPU usage in Activity Monitor is "diskimages-helpe" No, I didn't miss out an 'R' the process really is called that.
( Last edited by mattyb; Sep 9, 2009 at 04:58 PM. )
     
mduell
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Sep 9, 2009, 05:20 PM
 
How does the size of Downloads.dmg compare to your Downloads folder?

Why use a disk image?
     
mattyb  (op)
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Sep 9, 2009, 05:43 PM
 
Did a du -ks * under my home directory in Terminal and very worryingly it has 0 for Downloads. The Downloads.dmg file is 32.51G. Strange now the modified date is 20 mins old. It still has the Copying window up.

I was using a dmg because I'd never used a disk image as a sort of backup before. I was basically testing.

It is late here. I'm going to leave it as is, without touching anything, and look at it after work tomorrow.

It just stopped the copying window as I was closing the Terminal and Activity monitor. Plus, Downloads is a symlink under Desktop so I wouldn't have gotten a proper directory size reading.

TBH this behaviour has scared the sh1t out of me. 3 hours to create a 32G disk image file isn't great. Going to bed. Cheers for replying.
( Last edited by mattyb; Sep 9, 2009 at 05:50 PM. )
     
Art Vandelay
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Sep 9, 2009, 06:41 PM
 
It's going to take a while to compress a 32GB disk image. Let it do it's thing.
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mattyb  (op)
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Sep 10, 2009, 08:37 AM
 
Apologies for my post above. I was tired and quite frankly worried about what was happening. I edited the post several times and I should have written to that effect.

I shall finish my backups tonight, both with a TM backup, a clone using Disk Utility and using disk images for Documents, Music and Pictures. Three different drives so hopefully I have covered my you-know-what. Of course I also have backups to DVD.

Cheers for your replies, and once again sorry.

Matt
     
mduell
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Sep 10, 2009, 01:41 PM
 
Originally Posted by mattyb View Post
I was using a dmg because I'd never used a disk image as a sort of backup before. I was basically testing.

TBH this behaviour has scared the sh1t out of me. 3 hours to create a 32G disk image file isn't great. Going to bed. Cheers for replying.
Originally Posted by mattyb View Post
I shall finish my backups tonight, both with a TM backup, a clone using Disk Utility and using disk images for Documents, Music and Pictures. Three different drives so hopefully I have covered my you-know-what. Of course I also have backups to DVD.
The process scared the **** out of you during testing, so you're going to use it in production? Why not just use rsync? Music and Pictures aren't going to compress at all.
     
Cold Warrior
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Sep 10, 2009, 04:25 PM
 
It's also risky to entrust many files to a single file (dmg) that could be corrupted or lost. There's nothing wrong with having it (except the wait time) if you really want it, but I suggest making it a secondary or tertiary priority compared to incremental backups.
     
dimmer
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Sep 10, 2009, 08:09 PM
 
.dmg files are no different from any other file system. So a "corrupt" disk image is 1/unlikely and 2/you lose the corrupted files, everything else you can still access / open / copy.
     
mattyb  (op)
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Sep 11, 2009, 04:26 AM
 
Originally Posted by mduell View Post
The process scared the **** out of you during testing, so you're going to use it in production? Why not just use rsync? Music and Pictures aren't going to compress at all.
I various backup strategies :
1) Disk utility to make a clone of the internal hard drive to a FW external - a portable disk that I carry around.
2) Time Machine to backup to a USB connected external.
3) Create disk images and/or copies of folders to another FW connected external.
4) Burn to DVD

I didn't know that Music and pictures were uncompressable. I shall therefore not use compressed disk images for these directories.
     
mduell
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Sep 11, 2009, 05:41 PM
 
Originally Posted by dimmer View Post
.dmg files are no different from any other file system. So a "corrupt" disk image is 1/unlikely and 2/you lose the corrupted files, everything else you can still access / open / copy.
The issue is if you corrupt a few bits of a huge compressed disk image, you may not be able to read any of it. There's no reason to put it inside a disk image.

Originally Posted by mattyb View Post
I various backup strategies :
1) Disk utility to make a clone of the internal hard drive to a FW external - a portable disk that I carry around.
2) Time Machine to backup to a USB connected external.
3) Create disk images and/or copies of folders to another FW connected external.
4) Burn to DVD

I didn't know that Music and pictures were uncompressable. I shall therefore not use compressed disk images for these directories.
Just use rsync to copy the files for 3... disk images don't improve the situation any.
     
   
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