Re: Re-constructing disks

From: //Stany (stanyat_private)
Date: Tue Oct 16 2001 - 15:00:19 PDT

  • Next message: Kurt Seifried: "Re: Re-constructing disks"

    On Tue, 16 Oct 2001, Neil Long wrote:
    
    > Hello
    
    Hi, Neil
    
    > Disks keep getting bigger :-(
    
    Yes, they do.
    It's both a blessing and a curse, really.
    
    > It is straight forward to split up a large disk in to CD-R size chunks but
    > am I missing something painfully obvious for a reconstruction of a disk from
    > said CD-Rs? I assume you need a large holding disk in order to
    
    I assume you want an exact block by block disk copy including empty space,
    not just a copy of the files.
    
    > cat img.1 img.2 img.3 etc etc > /dev/disk-whatever (or using | dd
    > of=/dev/disk and options to maintain blocksizes, etc)
    >
    > [gzip, zcat, etc could be used to reduce the image sizes but becomes
    > somewhat hard to predict with regard to compressibility without a dry-run]
    >
    > Is there any easy way to append from individual CDs to a device file?
    
    It is probably possible to do something using dd and oseek, especially if
    your image on CDs is all spit up in even sized chunks, to make math easy.
    
    Then, probably, assuming you are on your third CD, and each previous image
    was 500 megs in size, you can probably do something like:
    dd if=/cdrom/image.2 bs=1024k oseek=1001 of=/dev/rdsk/c1t1d0s2
    
    Of course I am probably off with math, and this method doesn't let you you
    to use compression on the chunks, unless you want to do some more complex
    math.
    
    > Feel free to point out the painfully obvious and any hints as to what to do
    > as disks get way too big ;-)
    
    You can use dd and netcat to duplicate disks across the network.
    
    Something like: On the destination system:
    nc -l -p 1234 | dd of=/dev/rdsk/c1t1d0s2
    
    on the system from which you are duping a disk:
    dd if=/dev/rdsk/c7t0d0s2 | nc <ip of destination system> 1234
    
    We use this technique to clone standard OS load onto new user's desktops.
    
    Needless to say, it helps a great deal if you have nc on your forensic
    toolkit CD, you can put gzip in between netcat and reading/writing file to
    cut down on bandwidth, converting to use ssh is not that hard, etc.
    
    It also helps if your dd is sane and seprates stdout and stderr, and
    doesn't send "0+1 records in 0+1 records out" out to netcat.
    
    Oh, and you probably really want to use raw devices, unless you are only
    getting a single partition, etc...  I am sure you know more about
    filesystem layout then I do.
    
    Any way.  Hope this helps.  Have a nice day.
    
    > Cheers
    > Neil
    
    Signed:
    //Stany
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