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dd command

Discussion in 'Linux and Unix' started by BTex, Sep 1, 2004.

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  1. BTex

    BTex Thread Starter

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    A big part of my job is using the ghost software to collect and maintain customer images.
    But now I have found somthing that i cant ghost. (hidden partition) I have been told to boot to a knoppix cd and use a DD comant to sent a customer image tu to a server. (the server runs 2003 server. ) i figure i have to have a shared drive to do this, and that is about all I know a little advice would be appricated
    Randy
     
  2. saikee

    saikee

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    I think in Linux hidden partitions are distinguished from the others just by the file type and hence they are accessible in Linux.

    In dd the partition is copied sector by sector in native mode and hence the content and file type have no effect on the command.

    I am not too sure about the consequence of dd a source partition to a target partition of different size and have so far use dd successfully on partitions only of identical size.

    Also I haven't found out the exact reason why but using Suse 9.1 professional I can dd a 10Gb partition in about 4 to 5 minutes but it takes 1.5 hours on Knoppix 3.4. Both of them run 2.6 kernel but Suse does support 64 bit AMD processor which I got one in in the PC.

    I haven't found any software that can touch dd in term of performance and speed after trying to clone a 200Gb hard disk. Ghost took over 3 to 4 hours but Suse can dd it in 1.5 hours. The hard drive has XP and a bunch of Linux distros inside and multi-bootable as the original after cloning in both cases.
     
  3. tsunam

    tsunam

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    You should be fine backing it up since dd just copies the information byte for byte

    lets say for instance this hidden area is on the first hard drive partition 3. You'll do a

    dd if=/dev/<partition> of=<filename> (creates one of equal size)(i'll have to look at the man page for how to tell it to compress it)

    if you just want to automatically take it and shrink it do a

    dd if=/dev/<partition>| gzip -(1 or 9 depending on if you want fast or best compression) | dd of=<filename to gzip to> (that Should work....testing it now(1 gig with 9 compressed down to 1/2 size, 1 its down to about 2/3rds)so there is a difference, jsut depends on how large it is and how long yo uwant to commit to backing it up)
     
  4. Squashman

    Squashman Trusted Advisor

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  5. tsunam

    tsunam

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    that looks quite interesting LwdSquashman...I might have to look at it myself.
     
  6. saikee

    saikee

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    Sounds delicious to me too!
     
  7. Whiteskin

    Whiteskin

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    Just a warning... because it's gzipped it's sensitive to corruption (being one file). Make sure it's a good connection/medium you're using. I'd also md5 it at both ends.
     
  8. I Fix 4 U

    I Fix 4 U

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    well yay saikee's back. ps i did that dd stuff and the grub didnt work. so since this thread is about dd i'd like to pop in. i'll tell anyone here if i find anything helpful but saikee could you come to my grub problems thread or my xp+linux+98 thread (whichever one the moderator didnt close)
     
  9. lynch

    lynch

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    I believe partimage will save images across networks.
    HTH
    lynch
     
  10. I Fix 4 U

    I Fix 4 U

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    wow i linux tool i wish i woulda used that before i nuked my old computer. darnet well i may use it in the future, i always back up partitions before i reformat but i sure wish i coulda used partimage. i woulda just sent it 2 my new box.
     
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