Using 'dd' to extract files from DataPlow FS


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Thread: Using 'dd' to extract files from DataPlow FS

  1. #1
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    Using 'dd' to extract files from DataPlow FS

    I haven't been to this site in quite a while, since it changed from LNO in fact. Good to see this place is still around, albeit under a newer name.

    I'll get on with the problem. I've got a Netgear SC101T that I was using to store my files on. Some of you may know it uses the DataPlow SAN file system. It worked fine until I installed a firmware update which, for some reason, broke the mirror array. I've hated this POS ever since and want to pull the data from the drives and toss the box. The problem is, linux doesn't have support for this particular file system scheme.

    What I'm wondering is, how does 'dd' work, in regards to keeping the file system. Does it simply copy files and disregards the structure, or does it make an exact copy, DataPlow FS and all? Anyone else ran into this conundrum?

    Thanks!

  2. #2
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    I don't think dd really cares about file structure. As long as it can see the device it will do a bit by bit copy.
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  3. #3
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    My main concern is that I don't want to end up with another DataPlow filesystem that I can't access. I've tried copying from the ethernet box itself, but was sooooooooooooooooooooooo slow and it ended up timing out after a day or two. I just want something that can copy all of the data (about 4oo GB worth) in at least a few hours so that I can move on. I'm hoping 'dd' is the winner. I've got it started now so we'll see what the end result is. I guess worst case scenario is that it dupes the filesystem as well and I will have to wipe the new drive and find another solution. Keeping my fingers crossed though.

  4. #4
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    dd only copies the binary bits in the hard disk!

    dd differs from others by having nothing to do with what is inside the binary bits as they are just "1" or "0". Therefore you get an exact mirror image from the source.

    People use dd because the boot sector code, boot loaders and filing indices are not files so a file-based copying command doesn't work with them but dd can.
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  5. #5
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    You might want to give Photorec a go. It is a file recovery tool that ignores the filesystem when searching for files, so it may work for you so long as the files you want aren't fragmented, but it won't recover any of the directory structure or filenames. You'll find it included in the Testdisk package on most linux distros.

    Also as a rule, I prefer using ddrescue over dd for large copies or from damaged media, with ddrescue you get a progress indicator and it will automatically retry several times if the initial read fails and will skip over damaged portions if it can't successfully read part of a disk. What this means is that if the copy fails at some point, or you need to stop it, you can restart it from where it stopped, whereas dd wouldn't normally give you any indication of at which point it failed so you'd have to start the copy again from the beginning.

  6. #6
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    Quote Originally Posted by retsaw View Post
    You might want to give Photorec a go. It is a file recovery tool that ignores the filesystem when searching for files, so it may work for you so long as the files you want aren't fragmented, but it won't recover any of the directory structure or filenames. You'll find it included in the Testdisk package on most linux distros.

    Also as a rule, I prefer using ddrescue over dd for large copies or from damaged media, with ddrescue you get a progress indicator and it will automatically retry several times if the initial read fails and will skip over damaged portions if it can't successfully read part of a disk. What this means is that if the copy fails at some point, or you need to stop it, you can restart it from where it stopped, whereas dd wouldn't normally give you any indication of at which point it failed so you'd have to start the copy again from the beginning.
    Awesome! I'll give it a try. Thanks guys for the input!

  7. #7
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    Okay, latest conundrum:

    I performed dd_rescue on the drive in question and created an .img file on another drive with it. I go to mount the image, and it errors out out with "mount: you must specify the filesystem type".

    If I remember correctly, it was simply a matter of "mount -o loop imagename /directory

    or am I missing something? I'm hoping I didn't have this thing copying the drive for 4 days for nothing...

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