Having problems restoring image on USB Key

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jnapo
Posts: 1
Joined: Fri Nov 11, 2011 11:02 pm

Having problems restoring image on USB Key

Post by jnapo »

Alex

Great tool!

I must misunderstand the proper usage of the tool. I have created image backups of a USB Flash Drive. I have attempted to restore the Image to another USB Flash Drive that is identical to the original, same size, same manufacturer. When I do this I am informed that the image is larger than the device. I do not get it considering the image was created from a device that as far as I can tell is identical to the source.

Do you have any thoughts on what I may be doing wrong.

Thanks

Joe
Alex
Site Admin
Posts: 267
Joined: Fri Jul 29, 2011 11:59 pm

Re: Having problems restoring image on USB Key

Post by Alex »

Even if the brand and rough size might seem the same, USB flash drives can differ from lot to lot. So a Sandisk Cruzer with 8Gb can have a different size than the same product, that has been produced 1 or two months later. To restore an image to a device, it must have the exact or a larger size than the original.
DXW11
Posts: 2
Joined: Wed Nov 16, 2011 7:13 am

Re: Having problems restoring image on USB Key

Post by DXW11 »

I purchased 10 usb drives 4Gb imation brand then tried your tool and every drive was too small. So I tried by loading a bootable usb 4gb then making an image the formatted the drive then attampted to restore the same file to the same drive but it was too small . so then i tried to restore to a 8 Gb drive that worked.
Alex
Site Admin
Posts: 267
Joined: Fri Jul 29, 2011 11:59 pm

Re: Having problems restoring image on USB Key

Post by Alex »

The rule is simple. The physical size of the device (in Bytes, not Mbyte, not Gbyte) must be at least the same or higher than the exact size of the image (in Bytes). Larger devices will always work. Buying flash drives of the same brand and model might help, but it's not guaranteed they are identical. I for myself bought 3 Sandisk Cruzer from the same lot number and in that case they were identical, but in the case of flash drives 4Gb are not always equal to 4Gb.
DXW11
Posts: 2
Joined: Wed Nov 16, 2011 7:13 am

Re: Having problems restoring image on USB Key

Post by DXW11 »

Well I understand what your saying about the drive size.

Could I ask why when I use a Kingston 4Gb drive with 2Gb of data on it
1. Make an image of the Kingston 4Gb drive with 2Gb of data on it
2. Format the same 4Gb kingston drive. to remove the files
3. Attempt to restore the same image as created in step 1 on to the same drive.

Should the image file that is created be larger than the drive that it was imaged from ?
Should the size of the image file be the maximum size of the drive?
That is 4Gb drive with 1Mb of data . Image file is 4Gb.
Alex
Site Admin
Posts: 267
Joined: Fri Jul 29, 2011 11:59 pm

Re: Having problems restoring image on USB Key

Post by Alex »

The image size will be identical to the physical maximum file size. It doesn't matter if there is stored 1 MB or 4000 MB of file data on it. So for a 4Gb flash drive an raw image will always be 4Gb. If you choose compression, you might get smaller images, but that's not guaranteed. If there were a lot of files with bad compression conditions (jpeg images f.e.) on that drive, even if they are now deleted, the image size will still be large, even if the drive is empty now. This is caused by the way, most file systems (f.e. FAT) delete files. Even if you delete the file, the occupied space doesn't get filled with all zeroes (which can be compressed very good), but the occupied sectors are marked as free.
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